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Clinical Outcomes for Endovascular Repair of Thoracic Aortic Disease Using the Seal Thoracic Stent Graft: A Korean Multicenter Retrospective Study
CLINICAL STUDY
Clinical Outcomes for Endovascular Repair of Thoracic Aortic Disease Using the Seal Thoracic Stent Graft: A Korean Multicenter Retrospective Study Myung Gyu Song, MD, Young Kwon Cho, MD, Do Yun Lee, MD, Sung Bum Cho, MD, Hyun-Ki Yoon, MD, Se Hwan Kwon, MD, Hyo-Cheol Kim, MD, and Chang Jin Yoon, MD
ABSTRACT Purpose: To investigate the midterm outcomes of thoracic endovascular aneurysm repair (TEVAR) with the use of the Seal stent graft for four categories of thoracic aortic disease. Materials and Methods: This retrospective multicenter study evaluated the records of 216 Korean patients who underwent TEVAR with the Seal stent graft during 2007–2010. The study outcomes were (i) perioperative death, (ii) endoleak, (iii) repeat intervention, (iv) aortic-related death, and (v) all sudden unexplained late deaths. Results: The overall technical success rate was 94% (203 cases), and the disease-specific rates were 97% (88 cases) for aneurysms, 96% (71 cases) for dissections, 82% (32 cases) for traumatic aortic disease, and 100% (12 cases) for intramural hematoma and/or penetrating aortic ulcer. There were 6 acute surgical conversions (2 for aneurysms and 4 for dissections). There were 18 endoleaks, 4 retrograde ascending aortic dissections, and 6 stent graft–induced new entries. The 1-, 3-, and 5-year overall survival rates were 93% ⫾ 3, 90% ⫾ 4, and 90% ⫾ 4, respectively. Conclusions: TEVAR with the Seal thoracic stent graft provided a high technical success rate and low mortality and complication rates during midterm follow-up. However, additional long-term studies are needed to evaluate the durability and late complications associated with this device.
ABBREVIATIONS IMH = intramural hematoma, PAU = penetrating aortic ulcer, rAAD = retrograde ascending aorta dissection, SINE = stent graft– induced new entry, TAD = traumatic aortic disease, TEVAR = thoracic endovascular aneurysm repair
Thoracic endovascular aneurysm repair (TEVAR) was introduced in 1992. Since then, several studies (1–4) have found that this technique provides better therapeutic results and lower mortality and morbidity rates than conventional open thoracic repair for lesions in the descending thoracic aorta. Although the safety and
efficacy of TEVAR have been established for the treatment of thoracic aortic aneurysms and penetrating ulcers, a recent report of TEVAR for traumatic aortic transections and acute and chronic dissections (5) demonstrated favorable technical results and clinical outcomes.
From the Department of Radiology (M.G.S.), Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea; Department of Radiology (Y.K.C.), Kangdong Seong-Sim Hospital, Hallym University College of Medicine, Seoul, Korea; Department of Radiology and Research Institute of Radiological Science (D.Y.L.), Severance Hospital, Yonsei University College of Medicine, Seoul, Korea; Department of Radiology (S.B.C.), Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea; Department of Radiology and Research Institute of Radiology (H.-K.Y.), Asan Medical Center, Ulsan University College of Medicine, Seoul, Korea; Department of Radiology (S.H.K.), Kyung Hee University Medical Center, Kyung Hee University College of Medicin, Seoul, Korea; Department of Radiology (H.-C.K.), Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea; and Department of Radiology (C.J.Y.), Seoul National University Bundang Hospital, Seoul National
University College of Medicine, Seongnam, Korea. Received August 1, 2016; final revision received December 8, 2016; accepted December 28, 2016. Address correspondence to Y.K.C., Department of Radiology, Kangdong Seong-Sim Hospital, Hallym University College of Medicine, 150 Seongan-ro Gangdong-gu, Seoul 134-701, Korea; E-mail: [email protected] None of the authors have identified a conflict of interest. & SIR, 2017 J Vasc Interv Radiol 2017; XX:]]]–]]] http://dx.doi.org/10.1016/j.jvir.2016.12.1227
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The Seal thoracic stent graft (S & G Biotech, Seongnam, Korea) has been available since 2007 and was the only available device for TEVAR from 2007 to 2011 in Korea. The device consists of a modular system that includes self-expanding nitinol-alloy stent rings, fully covered Dacron graft materials, strong radial force, and an 18-F preloaded introducer (6). Because stent grafts from other manufacturers were unavailable during this period in Korea, we questioned how many patients were effectively treated with this device during this period and whether there were any differences in treatment results compared with findings from other recent studies (1–4). This retrospective study aimed to evaluate the midterm outcomes of TEVAR with the use of this device.
MATERIALS AND METHODS Patients The institutional review boards of all participating hospitals approved the study design and waived the requirement for informed consent based on the study’s retrospective design. A total of 318 patients who underwent TEVAR with the Seal thoracic stent graft at 16 Korean university hospitals during the period of 2007–2010 were evaluated. The specific indications for TEVAR for localized lesions at the descending thoracic aorta included the following: (i) aneurysm 4 4.5 cm and rapid aneurysm growth of 4 5 mm/y, (ii) acute dissection o 14 days with acute symptoms, (iii) acute disruption or transsection after trauma for traumatic aortic disease (TAD), and (iv) penetrating ulcer 4 10 mm and Z 20 mm in diameter for intramural hematoma (IMH) and/or penetrating aortic ulcer (PAU). Forty-seven cases were excluded because of incomplete, unanalyzable clinical and procedural data, and 55 TEVAR cases were excluded because they involved lesions at the ascending aorta (40 type A dissections, seven type A aneurysms), abdominal aorta involvement (four thoracoabdominal aortic aneurysms), or no true aneurysm (four mycotic aneurysms). Therefore, 216 patients with lesions located between zone II and the distal descending thoracic aorta and with complete midterm follow-up data were included in the analysis. The patients’ records contained baseline data regarding their demographic characteristics, comorbidities, American Society of Anesthesiologists physical status, anatomic characteristics of the target lesion, and details regarding the procedure (7). The 216 patients included 156 men (72%) and had a mean age of 62 years ⫾ 14 (median, 66 y; range, 19–89 y). The thoracic aortic diseases included true aneurysm (91 patients; 42%), type B dissection (74 patients; 34%), TAD (39 patients; 18%), and IMH and/or PAU (12 patients, 5%; n ¼ 6 with IMH and PAU, n ¼ 4 with PAU, and n ¼ 2 with IMH). The patient demographics and clinical characteristics are presented in Table 1.
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Procedure The Seal thoracic stent graft includes two parts. The first part is a proximal 3-cm bare-metal stent that is knitted and wound using a single thread of nitinol wire. The bare-metal stent has a diameter as large as 40 mm and a noninterlocking diamond-shaped pattern, as well as six proximal barbs to provide better fixation to the aortic wall. These barbs have inward-facing tips to prevent direct injury to the aortic wall. The second part is a distal full Dacron graft (Texan, Daegu, Korea). This graft is 6–10 cm long, has a diameter as large as 36 mm, is tied to the bare-metal stent by 4–0 Prolene blue monofilament on a tapered needle, and has gold radiopaque V-markers at the proximal and distal ends of the graft (Fig 1). The 18–22-mm stent grafts were introduced by using a 16-F introducer, and 24–40-mm stent grafts were introduced by using an 18-F introducer, which provides a lower introducer profile compared with other commercially available devices. The size of the stent graft was selected based on preTEVAR thoracic computed tomographic (CT) angiography, with oversizing of 10%–15% versus the diameter of the landing zone and 30–40 mm versus the length of the target lesion to ensure complete sealing of the landing zones (8). All procedures were performed by board-certificated interventional radiologists with 4 10 years of experience in aortic intervention.
Follow-up After the primary TEVAR procedure, all patients underwent follow-up CT angiography at 1 month, 3 months, 6 months, 12 months, and then annually after their discharge. All patients were specifically assessed for decrease in the aneurysm sac or in the false lumen of the dissection, endoleak, retrograde ascending aorta dissection (rAAD), stent graft–induced new entry (SINE), and stent graft–related complications. Findings from the follow-up visits were retrospectively evaluated; these included clinical examination findings, CT angiography, magnetic resonance imaging, and/or echocardiography. Causes of death were determined based on death certificates, medical records, and autopsy reports (if available).
Definitions The outcome reporting for the present study adhered to the guidelines from the ad hoc Committee for Standardized Reporting Practices in Vascular Surgery of the Society for Vascular Surgery/American Association for Vascular Surgery (9). In this context, technical success was related to periprocedural events that occurred between the initiation of the procedure and the first 24 hours after the procedure. Primary technical success was defined on an intent-to-treat basis and required the successful introduction and deployment of the device in the absence of surgical conversion, mortality, type I or
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Table 1 . Patient Demographic and Clinical Characteristics (N ¼ 216) Characteristic No. of Pts.
Aneurysm
Dissection
TADs
IMH/PAU
91 (42)
74 (34)
39 (18)
12 (5)
69 (76) 22 (24)
54 (73) 20 (27)
23 (59) 16 (41)
10 (83) 2 (17)
68 ⫾ 10 40–89
60 ⫾ 12 31–85
46 ⫾ 17 19–78
65 ⫾ 9 56–86
1 (1)
0
10 (26)
0
9 (10) 21 (23)
0 1 (1)
6 (15) 23 (59)
0 0
Sex Male Female Age (y) Mean ⫾ SD Range Shock Rupture Impending perforation Malperfusion syndrome
1 (1)
9 (12)
2 (5)
0
ASA status 4 4 Hypertension
21 (23) 70 (77)
12 (16) 65 (88)
24 (61) 13 (33)
2 (18) 7 (58)
Diabetes mellitus
21 (23)
5 (7)
3 (8)
0
Stroke Cerebrovascular accident
6 (6) 35 (38)
1 (1) 10 (13)
2 (5) 0
0 4 (36)
Peripheral vascular disease
19 (21)
8 (11)
0
0
Chronic renal failure More than two comorbidities
20 (22) 54 (59)
8 (11) 19 (26)
2 (5) 4 (10)
1 (9) 1 (9)
Prior PCI
36 (39)
8 (11)
1 (2)
4 (36)
Prior CABG Combined AAA
9 (10) 12 (13)
5 (7) 8 (11)
0 0
0 0
Note–Values in parentheses are percentages. AAA ¼ abdominal aortic aneurysm; ASA ¼ American Society of Anesthesiologists; CABG ¼ coronary artery bypass grafting; IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; PCI ¼ percutaneous coronary intervention; TAD ¼ traumatic aortic disease.
III endoleaks, and graft limb obstruction. However, the terms “primary technical success” and “secondary technical success” were used if unplanned endovascular or surgical procedures, respectively, were required (9). Clinical success was defined on an intent-to-treat basis and required successful deployment of the endovascular device at the intended location without death as a result of aneurysm-related treatment, type I or III endoleak, graft infection or thrombosis, aneurysm expansion (diameter of Z 5 mm or volume increase of Z 5%), aneurysm rupture, or conversion to open repair (9). Regarding major adverse events, aneurysm-related deaths were deaths that occurred in the hospital or within 30 days of the initial procedure or any repeat interventions or deaths caused by the aneurysm or the treatment device (9). Deaths that occurred o 30 days after the initial procedure were categorized as perioperative deaths, and deaths that occurred 4 30 days were categorized as late deaths (10). Endoleaks were defined by the persistence of blood flow outside the lumen of the endoluminal graft but within the aneurysm sac, as determined by an imaging study, and were classified as primary (o 30 d) or secondary (4 30 d) (10). Migration was defined as a graft shift Z 10 mm cranially or caudally in the aorta (10). Cases of rAAD were identified based on retrograde aortic dissection into the ascending aorta or the aortic root after TEVAR, and
SINE was defined as a new aortic tear that was caused by the ends of the stent graft (11–14).
Data Collection The patients’ electronic medical records were retrospectively examined to extract clinical findings, comorbidities, CT findings, and serial plain abdominal radiographs of the stent graft. The study endpoints were technical success, freedom from endoleak and repeat intervention, clinical success rate, aortic-related death, and all sudden unexplained late deaths.
Statistical Analysis The 30-day mortality rate; 1-, 3-, and 5-year survival rates; complications; and repeat interventions were estimated by Kaplan–Meier method. Cox multivariate analysis was used to evaluate the relationships between independent risk factors and acute postprocedural serious complications (myocardial infarction, stroke, and paraplegia). Categoric variables are reported as frequencies and percentages, and continuous variables are reported as means ⫾ standard deviations and/or medians and ranges. A P value of o .05 was considered statistically significant. All statistical analyses were performed by using SPSS software (version 11.0.1; SPSS, Chicago, Illinois).
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graft was used in 17 procedures, two stent grafts were used in one procedure, and three stent grafts were used in one procedure (Table 2). There were 31 cases of subclavian-to-carotid bypass and two cases of carotid-to-carotid bypass before TEVAR, as well as six cases of subclavian-to-carotid bypass after TEVAR. Prophylactic lumbar spinal drainage was performed for long lesions (410 cm) at the midportion of the thoracic aorta in 30 patients (14%; 20 aneurysms, eight dissections, and two cases of IMH and/ or PAU), and no significant complications were identified. A simultaneous abdominal aortic aneurysm was detected in 20 patients (9%); these cases were treated with endovascular aneurysm repair (n ¼ 4), surgery (n ¼ 3), or clinical observation (n ¼ 13; Table 2).
Primary Clinical Outcomes
Figure 1. The Seal thoracic stent graft includes two parts. (i) A proximal 3-cm bare-metal stent, knitted and wound using a single thread of nitinol wire, has a diameter as large as 40 mm and a noninterlocking diamond-shaped pattern, as well as six proximal barbs to provide better fixation to the aortic wall; the barbs have intentionally inward-facing tips (white arrows) to prevent direct injury to the aortic wall. (ii) A distal full Dacron graft, 6–10 cm long with a diameter as large as 36 mm, is tied to the bare-metal stent with 4–0 Prolene blue monofilament on a tapered needle, and gold radiopaque markers (black arrows) are attached to the proximal and distal parts of the Dacron graft.
RESULTS The initial TEVAR procedures included 158 elective procedures (73%) and 58 emergency treatments (27%). A total of 235 TEVAR procedures were performed, including 19 repeat interventions in 17 patients. The mean procedure time was 115 minutes ⫾ 45. During the initial TEVAR procedure, a single stent graft was implanted in 203 procedures, two stent grafts were used in 10 procedures, and three stent grafts were used in two procedures (mean number of stent grafts per patient, 1.1 ⫾ 0.1). During the repeat interventions, a single stent
Early outcomes. The overall technical success rate was 94% (203 cases), with rates of 97% (88 cases) for aneurysms, 96% (71 cases) for dissections, 82% (32 cases) for TAD, and 100% (12 cases) for IMH and/or PAU. The mean length of stay after the initial TEVAR procedure was 19 days ⫾ 13 (range, 1–204 d). There were six acute surgical conversions (o 30 d after TEVAR), with two cases in the aneurysm group and four in the dissection group. The causes of surgical conversion were type Ib endoleak and rAAD in the aneurysm group and type Ia endoleak, type Ib endoleak, rAAD, and distal SINE in the dissection group (Table 3). In the TAD group, the technical success rates for emergency and elective procedures were 79% (22 of 28) and 100% (11 of 11), respectively. The 30-day mortality rate was 4%, and the causes of death were sepsis and postoperative hypovolemia in the aneurysm group (n ¼ 2) and aortic rupture with severe multiple-organ injury in the TAD group (n ¼ 6). Another aortic rupture–related death occurred in the aneurysm group 18 days after repeat intervention, which was performed for SINE (with formation of a pseudoaneurysm) that was detected 30 days after the initial TEVAR procedure. The cumulative 1-year mortality rate was 7% (14 cases). Stroke (n ¼ 5) and paraplegia (n ¼ 2) occurred only in the aneurysm group. The cumulative 1-year survival rates were 91% ⫾ 6 for aneurysms, 97% ⫾ 4 for dissections, 84% ⫾ 11 for TAD, and 100% for IMH and/or PAU. The Kaplan–Meier estimates for 1-year freedom from endoleak, rAAD, SINE, and repeat intervention were 96% ⫾ 2, 99% ⫾ 1, 98% ⫾ 2, and 98% ⫾ 2, respectively. Late outcomes. In the aneurysm group, complete resolution was achieved in 81 patients (89%). One case of late aortic rupture–related death occurred 10 days after repeat intervention for SINE (with pseudoaneurysm formation) that was detected 2 years after the initial TEVAR procedure. Three cases of
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Table 2 . Anatomic, Lesion-Related, and Procedural Characteristics (N ¼ 216) Characteristic
Aneurysm
Dissection
TADs
IMH/PAU
No. of patients
91 (42)
74 (34)
39 (18)
12 (5)
Zone II Zone III
45 (49) 20 22)
0 69 (93)
1 (3) 38 (97)
4 (33) 8 (67)
Zone IV
13 (14)
4 (5)
0
0
13 (14)
1 (1)
0
0
49 ⫾19
NA
30 ⫾ 5
NA
Location of thoracic aorta disease*
Distal to zone IV Maximum TAA diameter (mm) Mean ⫾ SD Range Maximum true lumen diameter (mm) Mean ⫾ SD
15–108 NA
Range Minimum true lumen diameter (mm) Mean ⫾ SD Range Ruptured TAA Dissecting aneurysm Type of procedure Elective
21–39 34 ⫾ 4
NA
NA
NA
25–45 NA
17 ⫾ 6
NA
9 (10)
7–35 0
6 (15)
0
0
15 (20)
0
0 11 (92)
72 (79)
64 (86)
11 (16)
Emergency
19 (21)
10 (13)
28 (74)
1 (8)
Percutaneous Cutdown
66 (72) 12 (13)
54 (73) 13 (18)
35 (90) 1 (2)
10 (83) 1 (8)
Hybrid
13 (14)
7 (9)
3 (8)
1 (8)
Aortic debranching Preprocedure
17 (19)
3 (4)
7 (18)
2 (17)
Postprocedure
2 (2)
1 (1)
0
3 (25)
Stent-graft (initial TEVAR) Size range (mm) One stent Z 2 stents Repeat intervention Endovascular Surgery
28–48
29–46
22–38
30–38
83 (91)
70 (95)
39 (100)
11 (92)
8 (9)
4 (5)
0
1 (8)
15 (16)
3 (4)
0
1 (8)
2 (2)
4 (5)
0
0
Note–Values in parentheses are percentages. IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; TAA ¼ thoracic aortic aneurysm; TAD ¼ traumatic aortic disease; TEVAR ¼ thoracic endovascular aortic repair. *Zone II, from the left carotid artery up to and including the left subclavian artery; zone III, o 2 cm from the left subclavian artery; zone IV, 4 2 cm distal to the left subclavian artery; distal to zone IV, from 2 cm distal to the left subclavian artery to the thoracoabdominal aortic junction.
stent-graft migration occurred, only one of which was related to an endoleak. In the dissection group, one death occurred, which was related to severe postoperative hypovolemia after a second Bentall operation for rAAD, which occurred 18 months after the initial TEVAR procedure, and there was no stent-graft migration. The cumulative overall 5-year mortality rate was 10% (22 cases), and the deaths included 12 aortic-unrelated deaths and 10 aortic-related deaths (two cases of SINE in the aneurysm group, one case of rAAD in the dissection group, and seven cases of traumatic aortic rupture in the TAD group; Table 4).
During a mean follow-up of 56 months ⫾ 26 (median, 58 mo; range, 0–121 mo), the 1-year, 3-year, and 5-year overall survival rates were 93% ⫾ 3, 90% ⫾ 3, and 90% ⫾ 4, respectively (Fig 2). The specific 5-year survival rates were 90% ⫾ 6 for aneurysms, 91% ⫾ 6 for dissections, 84% ⫾ 11 for TAD, and 100% for IMH and/or PAU. There was no significant difference in the overall survival rates between the aneurysm and dissection groups (P ¼ .51). The Kaplan–Meier estimates for 5-year freedom from endoleak, rAAD, SINE, and repeat intervention were 89% ⫾ 5, 98% ⫾ 2, 97% ⫾ 5, and 87% ⫾ 5, respectively.
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Table 3 . Clinical Outcomes at 1 Year (N ¼ 216) Outcome
Aneurysm Dissection TADs IMH/PAU
No. of patients
91 (42)
74 (34)
39 (18)
Satisfactory CT
77 (85)
69 (93)
32 (82) 12 (100)
12 (5)
Primary
0
2 (3)
0
0
Secondary rAAD
3 (3) 1 (1)
2 (3) 1 (1)
0 0
0 0
SINE
3 (3)
1 (1)
0
0
Migration Aneurysm expansion
0 8 (9)
0 5 (7)
0 0
0 0
Repeat intervention
2 (2)
5 (7)
0
0
Aneurysm rupture Conversion to surgery
1 (1) 1* (1)
0 2 (3)
0 0
0 0
findings Endoleak
Death at 30 d
2 (2)
0
6 (15)
0
Aortic-related death Aortic-unrelated death
2 (2) 5 (5)
0 0
7 (18) 0
0 0
84 (92)
74 (100)
Cumulative survival
32 (82) 12 (100)
Note–Values in parentheses are percentages. IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; rAAD ¼ retrograde ascending aorta dissection; SINE ¼ stent graft-induced new entry; TAD ¼ traumatic aortic disease. *Surgical conversion after one failed intervention.
Table 4 . Clinical Outcomes at 5 Years (N ¼ 216) Outcome No. of patients Satisfactory CT
Aneurysm Dissection TADs IMH/PAU 91 (42) 72 (79)
74 (34) 65 (88)
39 (18) 12 (5) 32 (82) 12 (100)
Endoleak rAAD
9 (10) 0
2 (3) 2 (3)
0 0
0 0
SINE
1 (1)
1 (1)
0
0
1 (1) 8 (9)
0 3 (4)
0 0
0 0
10* (11)
3 (4)
0
0
0 1 (1)
0 2 (3)
0 0
0 0
0
1 (1)
0
0
2 (2) 82 (90)
5 (7) 68 (91)
findings
Migration Aneurysm expansion Repeat intervention Aneurysm rupture Conversion to surgery Aortic-related death Aortic-unrelated death Cumulative survival
0 0 32 (85) 12 (100)
Note–Values in parentheses are percentages. IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; rAAD ¼ retrograde ascending aorta dissection; SINE ¼ stent graft-induced new entry; TAD ¼ traumatic aortic disease. *One patient with three repeat interventions.
Secondary Clinical Outcomes Endoleaks. A total of 18 endoleaks were observed in 14 men and four women during the follow-up period (eight type Ia, eight type Ib, one type III, and one type IV; Table 5). Two primary type Ia endoleaks, which were detected on follow-up CT, occurred in the dissection group at 2 days and 6 days after the
Figure 2. Overall survival rates at 1, 3, and 5 years.
TEVAR procedure. The mean time to detect the 16 secondary endoleaks was 24 months ⫾ 18 (range, 2–51 mo); the mean times were 26 months ⫾ 16 (range, 5–51 mo) for the aneurysm group and 20 months ⫾ 13 (range, 0–52 mo) for the dissection group. The 1-, 3-, and 5-year rates of freedom from endoleak were 97% ⫾ 2, 93% ⫾ 3, and 89% ⫾ 5, respectively (Fig 3). Six endoleaks (two type Ia, three type IIb, and one type IIIa) were observed during the study period because they were clinically stable and had a small volume (four in the aneurysm group and two in the dissection group). These cases did not significantly affect the survival rate (P ¼ .32); however, endoleaks were significantly associated with clinical failure (P o .001).
rAAD and SINE. There were four cases of rAAD and six cases of SINE between the aneurysm group (n ¼ 5) and the dissection group (n ¼ 5; Table 5). The mean times to detect the four rAADs and six SINEs were 24 months ⫾ 16 (range, 0–48 mo) and 19 months ⫾ 14 (range, 1–42 mo), respectively. Three cases involved acute onset (o 30 d) after the initial TEVAR procedure (8 d and 22 d in the rAAD cases and 30 d in the SINE case); two rAAD cases were successfully managed with surgery, but repeat intervention failed for the SINE case (Table 3). Two cases of late-onset rAAD (4 30 d; 18 and 48 mo) were treated on a repeat basis with a Bentall operation in one case and with only clinical observation in the other case, based on the clinical stability and minimal extent of the rAAD. Five cases of late-onset SINE, which were detected at 5, 8, 10, 15, and 42 months after the initial TEVAR procedure, underwent three successful repeat interventions, one
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Table 5 . Overall Clinical Outcome after TEVAR (N ¼ 216) Outcome
Aneurysm
Dissection
TADs
IMH/PAU
91 (42)
74 (34)
39 (18)
12 (5)
Death at 30 d
2 (2)
0
6 (15)
0
Death at 1 y Death at 5 y
5 (5) 2 (2)
0 6 (8)
1 (3) 0
0 0
Primary clinical success
74 (81)
68 (92)
32 (82)
12 (100)
Primary assisted clinical success Secondary clinical success
9 (10) 2 (2)
1 (1) 3 (4)
0 0
0 0
5 (5) 2 (2)
3 (4) 2 (3)
0 0
0 0
No. of patients
Complications Stroke Paraplegia Endoleak
12 (13)
6 (8)
0
0
3 (3) 7 (8)
5 (7) 1 (1)
0 0
0 0
Type II
0
0
0
0
Type III Type IV
1 (1) 1 (1)
0 0
0 0
0 0
rAAD
1 (1)
3 (4)
0
0
SINE
4 (4)
2 (3)
0
0
Type Ia Type Ib
Note–Values in parentheses are percentages. IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; rAAD ¼ retrograde ascending aorta dissection; SINE ¼ stent graftinduced new entry; TAD ¼ traumatic aortic disease; TEVAR ¼ thoracic endovascular aortic repair.
Repeat Interventions Seventeen patients (8%) underwent 19 repeat interventions, including three repeat interventions in one patient, and the mean time to repeat intervention was 29 months ⫾ 22 (range, 0–70 mo). During all repeat interventions, stent-graft extensions were created by using the same Seal device. Two repeat interventions and one surgical procedure were performed for technical failure (aneurysm, n ¼ 1; dissection, n ¼ 2), which resulted in one failed repeat intervention in the aneurysm group and two successful procedures in the dissection group. Endoleak, rAAD, SINE, and a larger proximal landing zone (4 40 mm) were significantly associated with repeat intervention (P o .001). The 1-, 3-, and 5-year rates of freedom from repeat intervention were 98% ⫾ 2, 92% ⫾ 4, and 87% ⫾ 6, respectively.
Figure 3. Rates of freedom from endoleak at 1, 3, and 5 years.
failed repeat intervention, and one descending thoracic aorta bridging bypass surgery (Table 4). The 1-, 3-, and 5-year rates of freedom from rAAD were 99% ⫾ 1, 98% ⫾ 2, and 98% ⫾ 2, respectively. The 1-, 3-, and 5-year rates of freedom from SINE were 98% ⫾ 2, 97% ⫾ 2, and 97% ⫾ 2, respectively (Fig 4). Cases of rAAD and SINE were significantly associated with clinical failure (P o .001).
DISCUSSION The present retrospective multicenter study provides the first Korean data regarding the midterm outcomes of TEVAR with the use of the Seal stent graft. The outcomes from the present study compare favorably to the findings of previous studies in terms of the primary technical success rate and 30-day mortality, 1-year survival, and 5-year survival rates (15). In the present study, the aneurysm group exhibited a technical success rate of 97%, a 30-day mortality rate of 2%, a 5-year survival rate of 90%, a stroke incidence of
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Figure 4. Rates of freedom from rAAD and SINE at 1, 3, and 5 years.
5%, and a paraplegia incidence of 2%. These rates are better than the previously reported outcomes of a 30-day mortality rate of 5% and major neurologic complication incidence of 5% (16–19). The 14 repeat interventions in 12 patients in the aneurysm group also resulted in favorable outcomes compared with repeat interventions in previous studies, even though four repeat interventions failed in one case of SINE (caused by a severely kinked stent graft), one case of rAAD, and two cases of recurrent endoleaks. The dissection group exhibited a technical success rate of 95%, a 30-day mortality rate of 0%, and a 5-year survival rate of 92%. These outcomes are better than previously reported outcomes after endovascular treatment or open surgery; however, a direct comparison is limited by differences in the patient selection processes (20,21). Four technical failures occurred, all of which were related to acute type Ia endoleaks. The causes of type Ia endoleaks were one case of acute rAAD, which was successfully treated with an emergent Bentall operation, and three cases of complete sealing failure of the dissection flap after stent-graft implantation. Two endoleaks were considered stable and were followed only with observation based on the decreasing endoleak volume during follow-up, and one of the endoleaks was treated again; however, this approach ultimately failed because of a recurrent type Ia endoleak. Paraplegia was not observed in the dissection group, which is in agreement with a previously reported rate of 2% after TEVAR, and compares favorably to the reported rates of 7%–36% after surgery (22). The TAD group in the present study exhibited a technical success rate of 82%, a 30-day mortality rate of 15%, and a 5-year survival rate of 84%. These outcomes
compare favorably to the reported 30-day mortality rates of 15%–30% after surgery; however, an early mortality rate of 6% was observed in a previous study of endovascular treatment (15,23). The relatively high 30-day mortality rate in the present study was likely related to the patients’ complex clinical status (eg, six cases of complete aorta rupture and serious multipleorgan injuries). The incidence of endoleak in the present study (8%) was lower than those reported in previous studies (24). The most common cause of repeat intervention in the present study was type I endoleak, which typically requires repeat intervention or surgery, especially in cases of dissection. However, clinical observation alone is occasionally possible for a type Ia endoleak, and two cases of type Ia endoleak in the dissection group required only clinical observation during follow-up. In addition, three type Ib endoleaks and one type IIIa endoleak in the aneurysm group were clinically observed. All of these endoleaks occurred at the descending thoracic aorta, and clinical observation did not significantly affect the survival rate. Multiple factors may have contributed to these endoleaks, and most endoleaks may be related to stent-graft migration because of inadequate fixation, which may also be related to poor landing zone morphology (eg, large aortic diameter, short landing zone length, abrupt aortic angulation, and/or presence of thrombus) (25). However, in the present study, only one insignificant device migration was detected in the aneurysm group during follow-up. The occurrence of rAAD after TEVAR is an acute and life-threatening situation that is typically caused by the proximal bare springs of the stent graft, which are
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designed to provide strong radial force for proximal fixation (12,13). Another possible cause is the placement of an oversized stent graft in the aorta. Therefore, the proximal stent should not be oversized for cases of acute dissection, even though oversizing of 20%–30% may be useful for cases of aneurysm (12,13). In the present study, we observed two acute and two late-onset cases of rAAD, which were successfully managed via a Bentall operation in three cases and clinical observation in one case. All rAAD cases in the present study may have been the results of direct aortic wall injury from the proximal bare springs of the stent graft. If a new aortic tear is detected around a thoracic stent graft (ie, SINE), the proper initial management is optimal blood pressure control, rather than repeat intervention or surgery (14). There were six cases of SINE in the present study, which were addressed via repeat intervention (three successful and two failed) and one successful surgical procedure. The causes of two failed repeat interventions were (i) a severely kinked device after the primary TEVAR procedure, which was not overcome by stent-graft overlapping during the repeat intervention; and (ii) a sudden aortic rupture that occurred 17 days after repeat intervention with three overlapping stent grafts. In the present study, direct irritation of the aortic wall by the stent graft’s distal margin may have caused SINE despite the fact that the distal margin of the Seal stent graft is fully covered with Dacron graft. Therefore, stent grafts should be more flexible and have no bare surfaces at the distal margin to avoid damaging the vulnerable aortic wall or dissection flap (26,27). The Seal thoracic stent graft has several advantages compared with other devices: the six proximal barbs are inward-facing to promote proximal fixation and prevent aortic wall injury, and it has greater radial force, a fully covered Dacron graft to complete sealing, and a smaller introducer catheter. However, the greater radial force at the proximal end of this device increases the risk of direct aortic wall injury. Despite the difficulty in directly comparing this device versus other devices, the rates of aneurysm-related mortality and endoleak at the 5-year follow-up in the present study are comparable to findings of two recent studies (28,29) with other devices for thoracic aneurysm treatment: 2% vs 2.5% and 5.9% for aneurysm-related mortality and 10% vs 10.6% and 5.7% for endoleak at 5-year follow-up. The present study has several limitations. First, the study did not identify or analyze independent risk factors and comorbidities, as the disease categories were heterogeneous and incompletely recorded on the patients’ medical charts. Second, the study retrospectively analyzed the use of one device for four disease categories, based on a small sample of patients from multiple centers that used heterogeneous follow-up CT intervals. Third, the disproportionate number of cases and adverse events at each hospital may have affected the outcome
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analysis. Fourth, the study did not directly compare outcomes versus those reported for other devices and other midterm studies. Fifth, selection bias may have been present as a result of the retrospective study design, as there was heterogeneity in the subject population and procedure type (eg, percutaneous vs hybrid or elective procedure vs emergency). Sixth, early cases may have influenced the midterm outcomes, as preliminary problems with the stent spring and graft module may have increased the likelihood of complications over a prolonged follow-up period. Therefore, a study with longterm follow-up will be needed to detect any late events. Finally, we were unable to determine the risk factors and characteristics of type IV and V endoleaks because of the retrospective study design. In conclusion, the present multicenter study revealed a high technical success rate and low mortality and complication rates during midterm follow-up after TEVAR using the Seal thoracic stent graft. However, a study with longer follow-up is needed to evaluate the long-term durability of the Seal thoracic stent graft and any late aortic complications.
ACKNOWLEDGMENTS This research was supported by Hallym University Research Fund Grant HURF-2016-34.
REFERENCES 1. Dake MD, Miller DC, Semba CP, Mitchell RS, Walker PJ, Liddell RP. Transluminal placement of endovascular stent-grafts for the treatment of descending thoracic aortic aneurysms. N Engl J Med 1994; 331: 1729–1734. 2. Suzuki T, Mehta RH, Ince H, et al. Clinical profiles and outcomes of acute type B aortic dissection in the current era: lessons from the International Registry of Aortic Dissection (IRAD). Circulation 2003; 108 (Suppl II):II312–II317. 3. Olsson C, Thelin S, Ståhle E, Ekbom A, Granath F. Thoracic aortic aneurysm and dissection: increasing prevalence and improved outcomes reported in a nationwide population-based study of more than 14,000 cases from 1987 to 2002. Circulation 2006; 114:2611–2618. 4. Xiong J, Jiang B, Guo W, Wang SM, Tong XY. Endovascular stent graft placement in patients with type B aortic dissection: a meta-analysis in China. J Thorac Cardiovasc Surg 2009; 138:865–872. 5. Lee DY, Kang SG, Choi D, et al. Percutaneous modular stent-grafts in the treatment of abdominal aortic aneurysms. J Endovasc Ther 2003; 10: 752–759. 6. Mitchell RS, Ishimaru S, Ehrlich MP, et al. First International Summit on Thoracic Aortic Endografting: roundtable on thoracic aortic dissection as an indication for endografting. J Endovasc Ther 2002; 9(Suppl II): II98–II105. 7. Aronson WL, McAuliffe MS, Miller K. Variability in the american society of anesthesiologists physical status classification scale. AANA J 2003; 71:265–274. 8. Nienaber CA, Kische S, Ince H. Thoracic aortic stent-graft devices: problems, failure modes, and applicability. Semin Vasc Surg 2007; 20: 81–89. 9. Chaikof EL, Blankensteijn JD, Harris PL, et al. Reporting standards for endovascular aortic aneurysm repair. J Vasc Surg 2002; 35:1048–1060. 10. Leurs LJ, Bell R, Degrieck Y, et al. Endovascular treatment of thoracic aortic diseases: combined experience from the EUROSTAR and United Kingdom Thoracic Endograft registries. J Vasc Surg 2004; 40:670–679. 11. Eggebrecht H, Thompson M, Rousseau H, et al; European Registry on Endovascular Aortic Repair Complications. Retrograde ascending aortic
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dissection during or after thoracic aortic stent graft placement: insight from the European registry on endovascular aortic repair complications. Circulation 2009; 120(11 Suppl):S276–S281. Canaud L, Ozdemir BA, Patterson BO, Holt PJ, Loftus IM, Thompson MM. Retrograde aortic dissection after thoracic endovascular aortic repair. Ann Surg 2014; 260:389–395. Jánosi RA, Tsagakis K, Bettin M, et al. Thoracic aortic aneurysm expansion due to late distal stent graft-induced new entry. Catheter Cardiovasc Interv 2015; 85:E43–E53. Weng SH, Weng CF, Chen WY, et al. Reintervention for distal stent graft-induced new entry after endovascular repair with a stainless steelbased device in aortic dissection. J Vasc Surg 2013; 57:64–71. Lee WA, Daniels MJ, Beaver TM, Klodell CT, Raghinaru DE, Hess PJ Jr. Late outcomes of a single-center experience of 400 consecutive thoracic endovascular aortic repairs. Circulation 2011; 123:2938–2945. Walsh SR, Tang TY, Sadat U, et al. Endovascular stenting versus open surgery for thoracic aortic disease: systematic review and meta-analysis of perioperative results. J Vasc Surg 2008; 47:1094–1098. Greenberg R, Resh T, Nyman U, et al. Endovascular repair of descending thoracic aortic aneurysms: an early experience with intermediateterm follow-up. J Vasc Surg 2000; 31:147–156. Gravereaux EC, Faries PL, Burks JA, et al. Risk of spinal cord ischemia after endograft repair of thoracic aortic aneurysms. J Vasc Surg 2001; 34: 997–1003. Weigang E, Hartert M, Siegenthaler MP, et al. Perioperative management to improve neurologic outcome in thoracic or thoracoabdominal aortic stent-grafting. Ann Thorac Surg 2006; 82:1679–1687. Beregi JP, Haulon S, Otal P, et al. Endovascular treatment of acute complications associated with aortic dissection: midterm results from a multicenter study. J Endovasc Ther 2003; 10:486–493.
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21. Stone DH, Brewster DC, Kwolek CJ, et al. Stent-graft versus opensurgical repair of the thoracic aorta: mid-term results. J Vasc Surg 2006; 44:1188–1197. 22. Melissano G, Tshomba Y, Civilini E, Chiesa R. Disappointing results with a new commercially available thoracic endograft. J Vasc Surg 2004; 39:124–130. 23. Rousseau H, Elaassar O, Marcheix B, et al. The role of stent-grafts in the management of aortic trauma. Cardiovasc Intervent Radiol 2012; 35: 2–14. 24. Dake MD, Miller DC, Mitchell RS, Semba CP, Moore KA, Sakai T. The “first generation” of endovascular stent-grafts for patients with aneurysms of the descending thoracic aorta. J Thorac Cardiovasc Surg 1998; 116:689–703. 25. Resch T, Koul B, Dias NV, Lindblad B, Ivancev K. Changes in aneurysm morphology and stent-graft configuration after endovascular repair of aneurysms of the descending thoracic aorta. J Thorac Cardiovasc Surg 2001; 122:47–52. 26. Greenberg RK, Haulon S, Khwaja J, Fulton G, Ouriel K. Contemporary management of acute aortic dissection. J Endovasc Ther 2003; 10: 476–485. 27. Kato N, Hirano T, Kawaguchi T, et al. Aneurysmal degeneration of the aorta after stent-graft repair of acute aortic dissection. J Vasc Surg 2001; 34:513–518. 28. Makaroun MS, Dillavou ED, Wheatley GH, et al. Five-year results of endovascular treatment with the Gore TAG device compared with open repair of thoracic aortic aneurysms. J Vasc Surg 2008; 47: 912–918. 29. Matsumura JS, Melissano G, Cambria RP, et al. Five-year results of thoracic endovascular aortic repair with the Zenith TX2. J Vasc Surg 2014; 60:1–10.
Clinical Outcomes for Endovascular Repair of Thoracic Aortic Disease Using the Seal Thoracic Stent Graft: A Korean Multicenter Retrospective Study Myung Gyu Song, MD, Young Kwon Cho, MD, Do Yun Lee, MD, Sung Bum Cho, MD, Hyun-Ki Yoon, MD, Se Hwan Kwon, MD, Hyo-Cheol Kim, MD, and Chang Jin Yoon, MD
ABSTRACT Purpose: To investigate the midterm outcomes of thoracic endovascular aneurysm repair (TEVAR) with the use of the Seal stent graft for four categories of thoracic aortic disease. Materials and Methods: This retrospective multicenter study evaluated the records of 216 Korean patients who underwent TEVAR with the Seal stent graft during 2007–2010. The study outcomes were (i) perioperative death, (ii) endoleak, (iii) repeat intervention, (iv) aortic-related death, and (v) all sudden unexplained late deaths. Results: The overall technical success rate was 94% (203 cases), and the disease-specific rates were 97% (88 cases) for aneurysms, 96% (71 cases) for dissections, 82% (32 cases) for traumatic aortic disease, and 100% (12 cases) for intramural hematoma and/or penetrating aortic ulcer. There were 6 acute surgical conversions (2 for aneurysms and 4 for dissections). There were 18 endoleaks, 4 retrograde ascending aortic dissections, and 6 stent graft–induced new entries. The 1-, 3-, and 5-year overall survival rates were 93% ⫾ 3, 90% ⫾ 4, and 90% ⫾ 4, respectively. Conclusions: TEVAR with the Seal thoracic stent graft provided a high technical success rate and low mortality and complication rates during midterm follow-up. However, additional long-term studies are needed to evaluate the durability and late complications associated with this device.
ABBREVIATIONS IMH = intramural hematoma, PAU = penetrating aortic ulcer, rAAD = retrograde ascending aorta dissection, SINE = stent graft– induced new entry, TAD = traumatic aortic disease, TEVAR = thoracic endovascular aneurysm repair
Thoracic endovascular aneurysm repair (TEVAR) was introduced in 1992. Since then, several studies (1–4) have found that this technique provides better therapeutic results and lower mortality and morbidity rates than conventional open thoracic repair for lesions in the descending thoracic aorta. Although the safety and
efficacy of TEVAR have been established for the treatment of thoracic aortic aneurysms and penetrating ulcers, a recent report of TEVAR for traumatic aortic transections and acute and chronic dissections (5) demonstrated favorable technical results and clinical outcomes.
From the Department of Radiology (M.G.S.), Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea; Department of Radiology (Y.K.C.), Kangdong Seong-Sim Hospital, Hallym University College of Medicine, Seoul, Korea; Department of Radiology and Research Institute of Radiological Science (D.Y.L.), Severance Hospital, Yonsei University College of Medicine, Seoul, Korea; Department of Radiology (S.B.C.), Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea; Department of Radiology and Research Institute of Radiology (H.-K.Y.), Asan Medical Center, Ulsan University College of Medicine, Seoul, Korea; Department of Radiology (S.H.K.), Kyung Hee University Medical Center, Kyung Hee University College of Medicin, Seoul, Korea; Department of Radiology (H.-C.K.), Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea; and Department of Radiology (C.J.Y.), Seoul National University Bundang Hospital, Seoul National
University College of Medicine, Seongnam, Korea. Received August 1, 2016; final revision received December 8, 2016; accepted December 28, 2016. Address correspondence to Y.K.C., Department of Radiology, Kangdong Seong-Sim Hospital, Hallym University College of Medicine, 150 Seongan-ro Gangdong-gu, Seoul 134-701, Korea; E-mail: [email protected] None of the authors have identified a conflict of interest. & SIR, 2017 J Vasc Interv Radiol 2017; XX:]]]–]]] http://dx.doi.org/10.1016/j.jvir.2016.12.1227
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The Seal thoracic stent graft (S & G Biotech, Seongnam, Korea) has been available since 2007 and was the only available device for TEVAR from 2007 to 2011 in Korea. The device consists of a modular system that includes self-expanding nitinol-alloy stent rings, fully covered Dacron graft materials, strong radial force, and an 18-F preloaded introducer (6). Because stent grafts from other manufacturers were unavailable during this period in Korea, we questioned how many patients were effectively treated with this device during this period and whether there were any differences in treatment results compared with findings from other recent studies (1–4). This retrospective study aimed to evaluate the midterm outcomes of TEVAR with the use of this device.
MATERIALS AND METHODS Patients The institutional review boards of all participating hospitals approved the study design and waived the requirement for informed consent based on the study’s retrospective design. A total of 318 patients who underwent TEVAR with the Seal thoracic stent graft at 16 Korean university hospitals during the period of 2007–2010 were evaluated. The specific indications for TEVAR for localized lesions at the descending thoracic aorta included the following: (i) aneurysm 4 4.5 cm and rapid aneurysm growth of 4 5 mm/y, (ii) acute dissection o 14 days with acute symptoms, (iii) acute disruption or transsection after trauma for traumatic aortic disease (TAD), and (iv) penetrating ulcer 4 10 mm and Z 20 mm in diameter for intramural hematoma (IMH) and/or penetrating aortic ulcer (PAU). Forty-seven cases were excluded because of incomplete, unanalyzable clinical and procedural data, and 55 TEVAR cases were excluded because they involved lesions at the ascending aorta (40 type A dissections, seven type A aneurysms), abdominal aorta involvement (four thoracoabdominal aortic aneurysms), or no true aneurysm (four mycotic aneurysms). Therefore, 216 patients with lesions located between zone II and the distal descending thoracic aorta and with complete midterm follow-up data were included in the analysis. The patients’ records contained baseline data regarding their demographic characteristics, comorbidities, American Society of Anesthesiologists physical status, anatomic characteristics of the target lesion, and details regarding the procedure (7). The 216 patients included 156 men (72%) and had a mean age of 62 years ⫾ 14 (median, 66 y; range, 19–89 y). The thoracic aortic diseases included true aneurysm (91 patients; 42%), type B dissection (74 patients; 34%), TAD (39 patients; 18%), and IMH and/or PAU (12 patients, 5%; n ¼ 6 with IMH and PAU, n ¼ 4 with PAU, and n ¼ 2 with IMH). The patient demographics and clinical characteristics are presented in Table 1.
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Procedure The Seal thoracic stent graft includes two parts. The first part is a proximal 3-cm bare-metal stent that is knitted and wound using a single thread of nitinol wire. The bare-metal stent has a diameter as large as 40 mm and a noninterlocking diamond-shaped pattern, as well as six proximal barbs to provide better fixation to the aortic wall. These barbs have inward-facing tips to prevent direct injury to the aortic wall. The second part is a distal full Dacron graft (Texan, Daegu, Korea). This graft is 6–10 cm long, has a diameter as large as 36 mm, is tied to the bare-metal stent by 4–0 Prolene blue monofilament on a tapered needle, and has gold radiopaque V-markers at the proximal and distal ends of the graft (Fig 1). The 18–22-mm stent grafts were introduced by using a 16-F introducer, and 24–40-mm stent grafts were introduced by using an 18-F introducer, which provides a lower introducer profile compared with other commercially available devices. The size of the stent graft was selected based on preTEVAR thoracic computed tomographic (CT) angiography, with oversizing of 10%–15% versus the diameter of the landing zone and 30–40 mm versus the length of the target lesion to ensure complete sealing of the landing zones (8). All procedures were performed by board-certificated interventional radiologists with 4 10 years of experience in aortic intervention.
Follow-up After the primary TEVAR procedure, all patients underwent follow-up CT angiography at 1 month, 3 months, 6 months, 12 months, and then annually after their discharge. All patients were specifically assessed for decrease in the aneurysm sac or in the false lumen of the dissection, endoleak, retrograde ascending aorta dissection (rAAD), stent graft–induced new entry (SINE), and stent graft–related complications. Findings from the follow-up visits were retrospectively evaluated; these included clinical examination findings, CT angiography, magnetic resonance imaging, and/or echocardiography. Causes of death were determined based on death certificates, medical records, and autopsy reports (if available).
Definitions The outcome reporting for the present study adhered to the guidelines from the ad hoc Committee for Standardized Reporting Practices in Vascular Surgery of the Society for Vascular Surgery/American Association for Vascular Surgery (9). In this context, technical success was related to periprocedural events that occurred between the initiation of the procedure and the first 24 hours after the procedure. Primary technical success was defined on an intent-to-treat basis and required the successful introduction and deployment of the device in the absence of surgical conversion, mortality, type I or
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Table 1 . Patient Demographic and Clinical Characteristics (N ¼ 216) Characteristic No. of Pts.
Aneurysm
Dissection
TADs
IMH/PAU
91 (42)
74 (34)
39 (18)
12 (5)
69 (76) 22 (24)
54 (73) 20 (27)
23 (59) 16 (41)
10 (83) 2 (17)
68 ⫾ 10 40–89
60 ⫾ 12 31–85
46 ⫾ 17 19–78
65 ⫾ 9 56–86
1 (1)
0
10 (26)
0
9 (10) 21 (23)
0 1 (1)
6 (15) 23 (59)
0 0
Sex Male Female Age (y) Mean ⫾ SD Range Shock Rupture Impending perforation Malperfusion syndrome
1 (1)
9 (12)
2 (5)
0
ASA status 4 4 Hypertension
21 (23) 70 (77)
12 (16) 65 (88)
24 (61) 13 (33)
2 (18) 7 (58)
Diabetes mellitus
21 (23)
5 (7)
3 (8)
0
Stroke Cerebrovascular accident
6 (6) 35 (38)
1 (1) 10 (13)
2 (5) 0
0 4 (36)
Peripheral vascular disease
19 (21)
8 (11)
0
0
Chronic renal failure More than two comorbidities
20 (22) 54 (59)
8 (11) 19 (26)
2 (5) 4 (10)
1 (9) 1 (9)
Prior PCI
36 (39)
8 (11)
1 (2)
4 (36)
Prior CABG Combined AAA
9 (10) 12 (13)
5 (7) 8 (11)
0 0
0 0
Note–Values in parentheses are percentages. AAA ¼ abdominal aortic aneurysm; ASA ¼ American Society of Anesthesiologists; CABG ¼ coronary artery bypass grafting; IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; PCI ¼ percutaneous coronary intervention; TAD ¼ traumatic aortic disease.
III endoleaks, and graft limb obstruction. However, the terms “primary technical success” and “secondary technical success” were used if unplanned endovascular or surgical procedures, respectively, were required (9). Clinical success was defined on an intent-to-treat basis and required successful deployment of the endovascular device at the intended location without death as a result of aneurysm-related treatment, type I or III endoleak, graft infection or thrombosis, aneurysm expansion (diameter of Z 5 mm or volume increase of Z 5%), aneurysm rupture, or conversion to open repair (9). Regarding major adverse events, aneurysm-related deaths were deaths that occurred in the hospital or within 30 days of the initial procedure or any repeat interventions or deaths caused by the aneurysm or the treatment device (9). Deaths that occurred o 30 days after the initial procedure were categorized as perioperative deaths, and deaths that occurred 4 30 days were categorized as late deaths (10). Endoleaks were defined by the persistence of blood flow outside the lumen of the endoluminal graft but within the aneurysm sac, as determined by an imaging study, and were classified as primary (o 30 d) or secondary (4 30 d) (10). Migration was defined as a graft shift Z 10 mm cranially or caudally in the aorta (10). Cases of rAAD were identified based on retrograde aortic dissection into the ascending aorta or the aortic root after TEVAR, and
SINE was defined as a new aortic tear that was caused by the ends of the stent graft (11–14).
Data Collection The patients’ electronic medical records were retrospectively examined to extract clinical findings, comorbidities, CT findings, and serial plain abdominal radiographs of the stent graft. The study endpoints were technical success, freedom from endoleak and repeat intervention, clinical success rate, aortic-related death, and all sudden unexplained late deaths.
Statistical Analysis The 30-day mortality rate; 1-, 3-, and 5-year survival rates; complications; and repeat interventions were estimated by Kaplan–Meier method. Cox multivariate analysis was used to evaluate the relationships between independent risk factors and acute postprocedural serious complications (myocardial infarction, stroke, and paraplegia). Categoric variables are reported as frequencies and percentages, and continuous variables are reported as means ⫾ standard deviations and/or medians and ranges. A P value of o .05 was considered statistically significant. All statistical analyses were performed by using SPSS software (version 11.0.1; SPSS, Chicago, Illinois).
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graft was used in 17 procedures, two stent grafts were used in one procedure, and three stent grafts were used in one procedure (Table 2). There were 31 cases of subclavian-to-carotid bypass and two cases of carotid-to-carotid bypass before TEVAR, as well as six cases of subclavian-to-carotid bypass after TEVAR. Prophylactic lumbar spinal drainage was performed for long lesions (410 cm) at the midportion of the thoracic aorta in 30 patients (14%; 20 aneurysms, eight dissections, and two cases of IMH and/ or PAU), and no significant complications were identified. A simultaneous abdominal aortic aneurysm was detected in 20 patients (9%); these cases were treated with endovascular aneurysm repair (n ¼ 4), surgery (n ¼ 3), or clinical observation (n ¼ 13; Table 2).
Primary Clinical Outcomes
Figure 1. The Seal thoracic stent graft includes two parts. (i) A proximal 3-cm bare-metal stent, knitted and wound using a single thread of nitinol wire, has a diameter as large as 40 mm and a noninterlocking diamond-shaped pattern, as well as six proximal barbs to provide better fixation to the aortic wall; the barbs have intentionally inward-facing tips (white arrows) to prevent direct injury to the aortic wall. (ii) A distal full Dacron graft, 6–10 cm long with a diameter as large as 36 mm, is tied to the bare-metal stent with 4–0 Prolene blue monofilament on a tapered needle, and gold radiopaque markers (black arrows) are attached to the proximal and distal parts of the Dacron graft.
RESULTS The initial TEVAR procedures included 158 elective procedures (73%) and 58 emergency treatments (27%). A total of 235 TEVAR procedures were performed, including 19 repeat interventions in 17 patients. The mean procedure time was 115 minutes ⫾ 45. During the initial TEVAR procedure, a single stent graft was implanted in 203 procedures, two stent grafts were used in 10 procedures, and three stent grafts were used in two procedures (mean number of stent grafts per patient, 1.1 ⫾ 0.1). During the repeat interventions, a single stent
Early outcomes. The overall technical success rate was 94% (203 cases), with rates of 97% (88 cases) for aneurysms, 96% (71 cases) for dissections, 82% (32 cases) for TAD, and 100% (12 cases) for IMH and/or PAU. The mean length of stay after the initial TEVAR procedure was 19 days ⫾ 13 (range, 1–204 d). There were six acute surgical conversions (o 30 d after TEVAR), with two cases in the aneurysm group and four in the dissection group. The causes of surgical conversion were type Ib endoleak and rAAD in the aneurysm group and type Ia endoleak, type Ib endoleak, rAAD, and distal SINE in the dissection group (Table 3). In the TAD group, the technical success rates for emergency and elective procedures were 79% (22 of 28) and 100% (11 of 11), respectively. The 30-day mortality rate was 4%, and the causes of death were sepsis and postoperative hypovolemia in the aneurysm group (n ¼ 2) and aortic rupture with severe multiple-organ injury in the TAD group (n ¼ 6). Another aortic rupture–related death occurred in the aneurysm group 18 days after repeat intervention, which was performed for SINE (with formation of a pseudoaneurysm) that was detected 30 days after the initial TEVAR procedure. The cumulative 1-year mortality rate was 7% (14 cases). Stroke (n ¼ 5) and paraplegia (n ¼ 2) occurred only in the aneurysm group. The cumulative 1-year survival rates were 91% ⫾ 6 for aneurysms, 97% ⫾ 4 for dissections, 84% ⫾ 11 for TAD, and 100% for IMH and/or PAU. The Kaplan–Meier estimates for 1-year freedom from endoleak, rAAD, SINE, and repeat intervention were 96% ⫾ 2, 99% ⫾ 1, 98% ⫾ 2, and 98% ⫾ 2, respectively. Late outcomes. In the aneurysm group, complete resolution was achieved in 81 patients (89%). One case of late aortic rupture–related death occurred 10 days after repeat intervention for SINE (with pseudoaneurysm formation) that was detected 2 years after the initial TEVAR procedure. Three cases of
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Table 2 . Anatomic, Lesion-Related, and Procedural Characteristics (N ¼ 216) Characteristic
Aneurysm
Dissection
TADs
IMH/PAU
No. of patients
91 (42)
74 (34)
39 (18)
12 (5)
Zone II Zone III
45 (49) 20 22)
0 69 (93)
1 (3) 38 (97)
4 (33) 8 (67)
Zone IV
13 (14)
4 (5)
0
0
13 (14)
1 (1)
0
0
49 ⫾19
NA
30 ⫾ 5
NA
Location of thoracic aorta disease*
Distal to zone IV Maximum TAA diameter (mm) Mean ⫾ SD Range Maximum true lumen diameter (mm) Mean ⫾ SD
15–108 NA
Range Minimum true lumen diameter (mm) Mean ⫾ SD Range Ruptured TAA Dissecting aneurysm Type of procedure Elective
21–39 34 ⫾ 4
NA
NA
NA
25–45 NA
17 ⫾ 6
NA
9 (10)
7–35 0
6 (15)
0
0
15 (20)
0
0 11 (92)
72 (79)
64 (86)
11 (16)
Emergency
19 (21)
10 (13)
28 (74)
1 (8)
Percutaneous Cutdown
66 (72) 12 (13)
54 (73) 13 (18)
35 (90) 1 (2)
10 (83) 1 (8)
Hybrid
13 (14)
7 (9)
3 (8)
1 (8)
Aortic debranching Preprocedure
17 (19)
3 (4)
7 (18)
2 (17)
Postprocedure
2 (2)
1 (1)
0
3 (25)
Stent-graft (initial TEVAR) Size range (mm) One stent Z 2 stents Repeat intervention Endovascular Surgery
28–48
29–46
22–38
30–38
83 (91)
70 (95)
39 (100)
11 (92)
8 (9)
4 (5)
0
1 (8)
15 (16)
3 (4)
0
1 (8)
2 (2)
4 (5)
0
0
Note–Values in parentheses are percentages. IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; TAA ¼ thoracic aortic aneurysm; TAD ¼ traumatic aortic disease; TEVAR ¼ thoracic endovascular aortic repair. *Zone II, from the left carotid artery up to and including the left subclavian artery; zone III, o 2 cm from the left subclavian artery; zone IV, 4 2 cm distal to the left subclavian artery; distal to zone IV, from 2 cm distal to the left subclavian artery to the thoracoabdominal aortic junction.
stent-graft migration occurred, only one of which was related to an endoleak. In the dissection group, one death occurred, which was related to severe postoperative hypovolemia after a second Bentall operation for rAAD, which occurred 18 months after the initial TEVAR procedure, and there was no stent-graft migration. The cumulative overall 5-year mortality rate was 10% (22 cases), and the deaths included 12 aortic-unrelated deaths and 10 aortic-related deaths (two cases of SINE in the aneurysm group, one case of rAAD in the dissection group, and seven cases of traumatic aortic rupture in the TAD group; Table 4).
During a mean follow-up of 56 months ⫾ 26 (median, 58 mo; range, 0–121 mo), the 1-year, 3-year, and 5-year overall survival rates were 93% ⫾ 3, 90% ⫾ 3, and 90% ⫾ 4, respectively (Fig 2). The specific 5-year survival rates were 90% ⫾ 6 for aneurysms, 91% ⫾ 6 for dissections, 84% ⫾ 11 for TAD, and 100% for IMH and/or PAU. There was no significant difference in the overall survival rates between the aneurysm and dissection groups (P ¼ .51). The Kaplan–Meier estimates for 5-year freedom from endoleak, rAAD, SINE, and repeat intervention were 89% ⫾ 5, 98% ⫾ 2, 97% ⫾ 5, and 87% ⫾ 5, respectively.
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Table 3 . Clinical Outcomes at 1 Year (N ¼ 216) Outcome
Aneurysm Dissection TADs IMH/PAU
No. of patients
91 (42)
74 (34)
39 (18)
Satisfactory CT
77 (85)
69 (93)
32 (82) 12 (100)
12 (5)
Primary
0
2 (3)
0
0
Secondary rAAD
3 (3) 1 (1)
2 (3) 1 (1)
0 0
0 0
SINE
3 (3)
1 (1)
0
0
Migration Aneurysm expansion
0 8 (9)
0 5 (7)
0 0
0 0
Repeat intervention
2 (2)
5 (7)
0
0
Aneurysm rupture Conversion to surgery
1 (1) 1* (1)
0 2 (3)
0 0
0 0
findings Endoleak
Death at 30 d
2 (2)
0
6 (15)
0
Aortic-related death Aortic-unrelated death
2 (2) 5 (5)
0 0
7 (18) 0
0 0
84 (92)
74 (100)
Cumulative survival
32 (82) 12 (100)
Note–Values in parentheses are percentages. IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; rAAD ¼ retrograde ascending aorta dissection; SINE ¼ stent graft-induced new entry; TAD ¼ traumatic aortic disease. *Surgical conversion after one failed intervention.
Table 4 . Clinical Outcomes at 5 Years (N ¼ 216) Outcome No. of patients Satisfactory CT
Aneurysm Dissection TADs IMH/PAU 91 (42) 72 (79)
74 (34) 65 (88)
39 (18) 12 (5) 32 (82) 12 (100)
Endoleak rAAD
9 (10) 0
2 (3) 2 (3)
0 0
0 0
SINE
1 (1)
1 (1)
0
0
1 (1) 8 (9)
0 3 (4)
0 0
0 0
10* (11)
3 (4)
0
0
0 1 (1)
0 2 (3)
0 0
0 0
0
1 (1)
0
0
2 (2) 82 (90)
5 (7) 68 (91)
findings
Migration Aneurysm expansion Repeat intervention Aneurysm rupture Conversion to surgery Aortic-related death Aortic-unrelated death Cumulative survival
0 0 32 (85) 12 (100)
Note–Values in parentheses are percentages. IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; rAAD ¼ retrograde ascending aorta dissection; SINE ¼ stent graft-induced new entry; TAD ¼ traumatic aortic disease. *One patient with three repeat interventions.
Secondary Clinical Outcomes Endoleaks. A total of 18 endoleaks were observed in 14 men and four women during the follow-up period (eight type Ia, eight type Ib, one type III, and one type IV; Table 5). Two primary type Ia endoleaks, which were detected on follow-up CT, occurred in the dissection group at 2 days and 6 days after the
Figure 2. Overall survival rates at 1, 3, and 5 years.
TEVAR procedure. The mean time to detect the 16 secondary endoleaks was 24 months ⫾ 18 (range, 2–51 mo); the mean times were 26 months ⫾ 16 (range, 5–51 mo) for the aneurysm group and 20 months ⫾ 13 (range, 0–52 mo) for the dissection group. The 1-, 3-, and 5-year rates of freedom from endoleak were 97% ⫾ 2, 93% ⫾ 3, and 89% ⫾ 5, respectively (Fig 3). Six endoleaks (two type Ia, three type IIb, and one type IIIa) were observed during the study period because they were clinically stable and had a small volume (four in the aneurysm group and two in the dissection group). These cases did not significantly affect the survival rate (P ¼ .32); however, endoleaks were significantly associated with clinical failure (P o .001).
rAAD and SINE. There were four cases of rAAD and six cases of SINE between the aneurysm group (n ¼ 5) and the dissection group (n ¼ 5; Table 5). The mean times to detect the four rAADs and six SINEs were 24 months ⫾ 16 (range, 0–48 mo) and 19 months ⫾ 14 (range, 1–42 mo), respectively. Three cases involved acute onset (o 30 d) after the initial TEVAR procedure (8 d and 22 d in the rAAD cases and 30 d in the SINE case); two rAAD cases were successfully managed with surgery, but repeat intervention failed for the SINE case (Table 3). Two cases of late-onset rAAD (4 30 d; 18 and 48 mo) were treated on a repeat basis with a Bentall operation in one case and with only clinical observation in the other case, based on the clinical stability and minimal extent of the rAAD. Five cases of late-onset SINE, which were detected at 5, 8, 10, 15, and 42 months after the initial TEVAR procedure, underwent three successful repeat interventions, one
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Table 5 . Overall Clinical Outcome after TEVAR (N ¼ 216) Outcome
Aneurysm
Dissection
TADs
IMH/PAU
91 (42)
74 (34)
39 (18)
12 (5)
Death at 30 d
2 (2)
0
6 (15)
0
Death at 1 y Death at 5 y
5 (5) 2 (2)
0 6 (8)
1 (3) 0
0 0
Primary clinical success
74 (81)
68 (92)
32 (82)
12 (100)
Primary assisted clinical success Secondary clinical success
9 (10) 2 (2)
1 (1) 3 (4)
0 0
0 0
5 (5) 2 (2)
3 (4) 2 (3)
0 0
0 0
No. of patients
Complications Stroke Paraplegia Endoleak
12 (13)
6 (8)
0
0
3 (3) 7 (8)
5 (7) 1 (1)
0 0
0 0
Type II
0
0
0
0
Type III Type IV
1 (1) 1 (1)
0 0
0 0
0 0
rAAD
1 (1)
3 (4)
0
0
SINE
4 (4)
2 (3)
0
0
Type Ia Type Ib
Note–Values in parentheses are percentages. IMH ¼ intramural hematoma; PAU ¼ penetrating aortic ulcer; rAAD ¼ retrograde ascending aorta dissection; SINE ¼ stent graftinduced new entry; TAD ¼ traumatic aortic disease; TEVAR ¼ thoracic endovascular aortic repair.
Repeat Interventions Seventeen patients (8%) underwent 19 repeat interventions, including three repeat interventions in one patient, and the mean time to repeat intervention was 29 months ⫾ 22 (range, 0–70 mo). During all repeat interventions, stent-graft extensions were created by using the same Seal device. Two repeat interventions and one surgical procedure were performed for technical failure (aneurysm, n ¼ 1; dissection, n ¼ 2), which resulted in one failed repeat intervention in the aneurysm group and two successful procedures in the dissection group. Endoleak, rAAD, SINE, and a larger proximal landing zone (4 40 mm) were significantly associated with repeat intervention (P o .001). The 1-, 3-, and 5-year rates of freedom from repeat intervention were 98% ⫾ 2, 92% ⫾ 4, and 87% ⫾ 6, respectively.
Figure 3. Rates of freedom from endoleak at 1, 3, and 5 years.
failed repeat intervention, and one descending thoracic aorta bridging bypass surgery (Table 4). The 1-, 3-, and 5-year rates of freedom from rAAD were 99% ⫾ 1, 98% ⫾ 2, and 98% ⫾ 2, respectively. The 1-, 3-, and 5-year rates of freedom from SINE were 98% ⫾ 2, 97% ⫾ 2, and 97% ⫾ 2, respectively (Fig 4). Cases of rAAD and SINE were significantly associated with clinical failure (P o .001).
DISCUSSION The present retrospective multicenter study provides the first Korean data regarding the midterm outcomes of TEVAR with the use of the Seal stent graft. The outcomes from the present study compare favorably to the findings of previous studies in terms of the primary technical success rate and 30-day mortality, 1-year survival, and 5-year survival rates (15). In the present study, the aneurysm group exhibited a technical success rate of 97%, a 30-day mortality rate of 2%, a 5-year survival rate of 90%, a stroke incidence of
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Figure 4. Rates of freedom from rAAD and SINE at 1, 3, and 5 years.
5%, and a paraplegia incidence of 2%. These rates are better than the previously reported outcomes of a 30-day mortality rate of 5% and major neurologic complication incidence of 5% (16–19). The 14 repeat interventions in 12 patients in the aneurysm group also resulted in favorable outcomes compared with repeat interventions in previous studies, even though four repeat interventions failed in one case of SINE (caused by a severely kinked stent graft), one case of rAAD, and two cases of recurrent endoleaks. The dissection group exhibited a technical success rate of 95%, a 30-day mortality rate of 0%, and a 5-year survival rate of 92%. These outcomes are better than previously reported outcomes after endovascular treatment or open surgery; however, a direct comparison is limited by differences in the patient selection processes (20,21). Four technical failures occurred, all of which were related to acute type Ia endoleaks. The causes of type Ia endoleaks were one case of acute rAAD, which was successfully treated with an emergent Bentall operation, and three cases of complete sealing failure of the dissection flap after stent-graft implantation. Two endoleaks were considered stable and were followed only with observation based on the decreasing endoleak volume during follow-up, and one of the endoleaks was treated again; however, this approach ultimately failed because of a recurrent type Ia endoleak. Paraplegia was not observed in the dissection group, which is in agreement with a previously reported rate of 2% after TEVAR, and compares favorably to the reported rates of 7%–36% after surgery (22). The TAD group in the present study exhibited a technical success rate of 82%, a 30-day mortality rate of 15%, and a 5-year survival rate of 84%. These outcomes
compare favorably to the reported 30-day mortality rates of 15%–30% after surgery; however, an early mortality rate of 6% was observed in a previous study of endovascular treatment (15,23). The relatively high 30-day mortality rate in the present study was likely related to the patients’ complex clinical status (eg, six cases of complete aorta rupture and serious multipleorgan injuries). The incidence of endoleak in the present study (8%) was lower than those reported in previous studies (24). The most common cause of repeat intervention in the present study was type I endoleak, which typically requires repeat intervention or surgery, especially in cases of dissection. However, clinical observation alone is occasionally possible for a type Ia endoleak, and two cases of type Ia endoleak in the dissection group required only clinical observation during follow-up. In addition, three type Ib endoleaks and one type IIIa endoleak in the aneurysm group were clinically observed. All of these endoleaks occurred at the descending thoracic aorta, and clinical observation did not significantly affect the survival rate. Multiple factors may have contributed to these endoleaks, and most endoleaks may be related to stent-graft migration because of inadequate fixation, which may also be related to poor landing zone morphology (eg, large aortic diameter, short landing zone length, abrupt aortic angulation, and/or presence of thrombus) (25). However, in the present study, only one insignificant device migration was detected in the aneurysm group during follow-up. The occurrence of rAAD after TEVAR is an acute and life-threatening situation that is typically caused by the proximal bare springs of the stent graft, which are
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designed to provide strong radial force for proximal fixation (12,13). Another possible cause is the placement of an oversized stent graft in the aorta. Therefore, the proximal stent should not be oversized for cases of acute dissection, even though oversizing of 20%–30% may be useful for cases of aneurysm (12,13). In the present study, we observed two acute and two late-onset cases of rAAD, which were successfully managed via a Bentall operation in three cases and clinical observation in one case. All rAAD cases in the present study may have been the results of direct aortic wall injury from the proximal bare springs of the stent graft. If a new aortic tear is detected around a thoracic stent graft (ie, SINE), the proper initial management is optimal blood pressure control, rather than repeat intervention or surgery (14). There were six cases of SINE in the present study, which were addressed via repeat intervention (three successful and two failed) and one successful surgical procedure. The causes of two failed repeat interventions were (i) a severely kinked device after the primary TEVAR procedure, which was not overcome by stent-graft overlapping during the repeat intervention; and (ii) a sudden aortic rupture that occurred 17 days after repeat intervention with three overlapping stent grafts. In the present study, direct irritation of the aortic wall by the stent graft’s distal margin may have caused SINE despite the fact that the distal margin of the Seal stent graft is fully covered with Dacron graft. Therefore, stent grafts should be more flexible and have no bare surfaces at the distal margin to avoid damaging the vulnerable aortic wall or dissection flap (26,27). The Seal thoracic stent graft has several advantages compared with other devices: the six proximal barbs are inward-facing to promote proximal fixation and prevent aortic wall injury, and it has greater radial force, a fully covered Dacron graft to complete sealing, and a smaller introducer catheter. However, the greater radial force at the proximal end of this device increases the risk of direct aortic wall injury. Despite the difficulty in directly comparing this device versus other devices, the rates of aneurysm-related mortality and endoleak at the 5-year follow-up in the present study are comparable to findings of two recent studies (28,29) with other devices for thoracic aneurysm treatment: 2% vs 2.5% and 5.9% for aneurysm-related mortality and 10% vs 10.6% and 5.7% for endoleak at 5-year follow-up. The present study has several limitations. First, the study did not identify or analyze independent risk factors and comorbidities, as the disease categories were heterogeneous and incompletely recorded on the patients’ medical charts. Second, the study retrospectively analyzed the use of one device for four disease categories, based on a small sample of patients from multiple centers that used heterogeneous follow-up CT intervals. Third, the disproportionate number of cases and adverse events at each hospital may have affected the outcome
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analysis. Fourth, the study did not directly compare outcomes versus those reported for other devices and other midterm studies. Fifth, selection bias may have been present as a result of the retrospective study design, as there was heterogeneity in the subject population and procedure type (eg, percutaneous vs hybrid or elective procedure vs emergency). Sixth, early cases may have influenced the midterm outcomes, as preliminary problems with the stent spring and graft module may have increased the likelihood of complications over a prolonged follow-up period. Therefore, a study with longterm follow-up will be needed to detect any late events. Finally, we were unable to determine the risk factors and characteristics of type IV and V endoleaks because of the retrospective study design. In conclusion, the present multicenter study revealed a high technical success rate and low mortality and complication rates during midterm follow-up after TEVAR using the Seal thoracic stent graft. However, a study with longer follow-up is needed to evaluate the long-term durability of the Seal thoracic stent graft and any late aortic complications.
ACKNOWLEDGMENTS This research was supported by Hallym University Research Fund Grant HURF-2016-34.
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