- Email: [email protected]
Outcomes after stent graft therapy for dissection-related aneurysmal degeneration in the descending thoracic aorta
From the Western Vascular Society
Outcomes after stent graft therapy for dissection-related aneurysmal degeneration in the descending thoracic aorta Derek P. Nathan, MD,a Sherene Shalhub, MD, MPH,a Gale L. Tang, MD,a Matthew P. Sweet, MD,a Edward D. Verrier, MD,b Nam T. Tran, MD,a Gabriel S. Aldea, MD,b and Benjamin W. Starnes, MD,a Seattle, Wash Objective: Stent graft therapy has emerged as an alternative to open surgery in the management of chronic dissectionrelated aneurysmal degeneration (DRAD) in the descending thoracic aorta (DTA). The incidence of perioperative complications, need for secondary aortic intervention (SAI), and rate of aneurysmal false-lumen thrombosis have not been thoroughly described. Methods: Perioperative and midterm outcomes in patients who underwent stent graft therapy for chronic DRAD DTA at a single institution between January 2006 and September 2013 were retrospectively analyzed. Preoperative anatomic factors, including the number of visceral and renal side branches off the false lumen, and false lumen volume, were analyzed for their ability to predict treatment failure. Treatment failure was defined as death, need for a SAI, and failure to achieve thrombosis of the DRAD DTA. Treatment success was defined as thrombosis of the false lumen in the area of the DRAD DTA with stability or a decrease in the maximum diameter of the DRAD DTA. Results: During the study period, 47 patients underwent stent graft therapy for chronic DRAD DTA. Patients were a mean age of 58.3 6 11.7 years, 74.5% (n [ 35) were male, and 14.9% (n [ 7) had a history of connective tissue disease. The left subclavian artery was covered in 48.9% (n [ 23), and revascularization was performed in 87.0% (n [ 20). Spinal drains were used in 74.5% (n [ 35). Spinal cord ischemia developed in 6.4% (n [ 3), which resolved in two and improved in one. No retrograde aortic dissections occurred. The 30-day mortality was 4.3% (n [ 2); one death was in a patient with rupture. Mean clinical follow-up was 35.1 6 20.9 months. The 5-year Kaplan-Meier survival was 89% 6 5%. Treatment failure occurred in 18 patients (38.3%): 9 required SAIs, 6 did not have thrombosis of the false lumen in the area of the DRAD DTA, and 4 died, with 1 patient dying during a SAI. No preoperative anatomic factor predicted treatment failure. The 5-year freedom from treatment failure was 54% 6 9%. Including the nine patients who underwent SAI, treatment success was achieved in 85.2% of patients. Conclusions: In this single-center experience of stent graft therapy for chronic DRAD DTA, treatment success was achieved in 85% of patients after a SAI rate of 20%. No preoperative anatomic factor predicted treatment failure, which occurred in almost 40% of the patients. Identifying predictors of treatment failure may improve future outcomes. (J Vasc Surg 2015;61:1200-7.)
Dissection-related aneurysmal degeneration (DRAD) in the descending thoracic aorta (DTA) occurs in 20% of medically managed uncomplicated acute type B dissections, and it has been associated with a >30% incidence of rupture once the DRAD DTA is >6 cm.1 A recent study of medical management of acute uncomplicated From the Divisions of Vascular Surgerya and Cardiac Surgery,b University of Washington. Author conflict of interest: none. Presented at the Twenty-ninth Annual Meeting of the Western Vascular Society, Coronado, Calif, September 20-23, 2014. Reprint requests: Benjamin W. Starnes, MD, University of Washington/ Harborview Medical Center, 325 9th Ave, Box 359908, Seattle, WA 98104 (e-mail: [email protected]). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2015 by the Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jvs.2014.12.040
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type B dissections reported a 60% failure rate, which was defined as subsequent need for aortic intervention or death.2 Open surgical repair of chronic DRAD DTA carries significant risks, including a 30-day mortality of 10%, and rates of paraplegia, renal failure, and pulmonary failure of 10%.3,4 Stent graft therapy has emerged as an alternative to open surgery, with low rates of perioperative morbidity and mortality and high rates of false lumen thrombosis.3,5-8 Although stent graft therapy for DRAD DTA appears promising, retrograde aortic dissection, spinal cord ischemia, and the need for secondary aortic intervention (SAI) have been identified as areas of concern.6,8 Given these concerns, identifying predictors of suboptimal outcomes after stent graft therapy for chronic DRAD DTA is an important area of investigation. Previous work has identified false lumen volume and number of side branches off the false lumen as preoperative determinants that have a potential affect on postoperative outcomes.7,9
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This study investigated a single-center experience with stent graft therapy for chronic DRAD DTA and sought to identify predictors of treatment failure. We hypothesized that preoperative anatomic factors, including false lumen volume and number of renal and visceral vessels arising from the false lumen, would predict treatment failure.9 METHODS This study was conducted with the approval of the University of Washington Human Research Ethics Committee. The need for informed consent from the patients was waived. Study cohort. A retrospective study was performed of patients who underwent stent graft therapy for chronic DRAD DTA between January 2006 and September 2013 at a single institution. Chronic DRAD DTA was defined by the presence of aortic dissection for >2 weeks.7 Clinical practice. All patients underwent fine-cut computed tomography angiography (CTA) to assist with planning of the stent graft procedure. Initially, the main goal of therapy was to cover the primary entry tear; however, this approach evolved to favor coverage of the entire DTA. Intravascular ultrasound imaging was used in all cases to confirm wire position in the true lumen and assist with sizing of the stent graft. Stent grafts were oversized by w10% to 15% according to the diameter of the normal aorta in the proximal landing zone. With respect to the distal landing zone, sizing was to the diameter of the true and false lumen. If the true lumen was narrowed significantly distally, a tapered stent graft was used. Balloon angioplasty of the proximal and distal landing zone was not routinely performed. At the start of the study period, revascularization of the left subclavian artery was performed at the discretion of the surgeon. However, left subclavian artery revascularization is now routine. Management of visceral or renal vessels that arose from the false lumen was at the surgeon’s discretion. Aortic analysis and volume measurements. Preoperative CTA scans were analyzed on an Aquarius iNtuition workstation (TeraRecon, San Mateo, Calif). The luminal origin of the renal arteries, superior mesenteric artery, and celiac artery was determined. The origin of the inferior mesenteric artery and common iliac arteries was not evaluated. A vessel that arose from both the true and false lumen was classified as arising from the false lumen. The preoperative volume of the true and false lumen in the DTA and abdominal aorta was measured using a semiautomatic segmentation method by one of the authors (D.P.N.). In brief, a centerline was created in the true and false lumen, and the area of each orthogonal CTA cut was measured. Flow lumen and thrombus were both included in the measurements. The DTA was defined as the left subclavian artery to the celiac artery, and the abdominal aorta was defined as the celiac artery to the aortic bifurcation. The postoperative volume of the DTA and abdominal aorta was not measured. Thrombosis of the false lumen was determined through examination of the patient’s last postoperative
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Table I. Preoperative characteristics of patients undergoing stent graft therapy for dissection-related aneurysmal degeneration (DRAD) of the descending thoracic aorta (DTA) Feature Age, years Male Hypertension Previous aortic operation Type A dissection repair Aortic arch repair (including debranching procedures) Abdominal aortic aneurysm repair Indication for intervention Aneurysm size $5.5 cm Aneurysm expansion $0.5 cm over 6 months Refractory chest pain Rupture
Mean 6 SD or No. (%) 58.3 6 11.7 35 (74.5) 41 (87.2) 13 (27.7) 8 (17.0) 8 (17.0) 35 (74.5) 8 (17.0) 2 (4.3) 2 (4.3)
SD, Standard deviation.
CTA, including arterial and delayed imaging. The diameter at the point of maximal DRAD DTA was measured on the patient’s preoperative and last postoperative CTA. If no treatment failure occurred, follow-up imaging consisted of a CTA with arterial and delayed imaging at 1 month and annually thereafter. Study outcomes and statistical analysis. Study outcomes included perioperative morbidity and mortality, midterm survival, and treatment failure and success. Treatment failure was a composite, including aortic-related and nonaortic-related death, need for SAI, and failure to achieve thrombosis of the false lumen in the area of the DRAD DTA. Criteria for treatment success included thrombosis of the false lumen in the area of the DRAD DTA, with stability or a decrease in the maximum diameter of the DRAD DTA. The number of renal and visceral arteries off the false lumen and the preoperative volume of the true and false lumens in the DTA and the abdominal aorta were analyzed for their ability to predict treatment failure. These variables were selected on the basis of a previous investigation and to focus on the potential identification of preoperative anatomic predictors of treatment failure.9 Statistical analysis was performed with GraphPad Prism software (GraphPad Software Inc, La Jolla, Calif). Univariate analysis with c2 test, paired t-test, and Mann-Whitney U test was performed, as appropriate. Survival and freedom from treatment failure were determined using Kaplan-Meier analysis. RESULTS During the study period, 47 patients underwent stent graft therapy for chronic DRAD DTA. Seven patients (14.9%) had connective tissue disease; five (71.4%) of these patients had previously undergone repair of type A dissections, followed by arch debranching procedures or arch
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Table II. Operative details of patients undergoing stent graft therapy for dissection-related aneurysmal degeneration (DRAD) of the descending thoracic aorta (DTA) Feature Stent graft TX2a TAGb Talentc Cerebrospinal fluid drainage Left subclavian artery Coverage Revascularization Visceral or renal stent Abdominal debranching plus stent graft procedure
No (%) 40 4 3 35
(85.1) (8.5) (6.4) (74.5)
23 20 6 2
(48.9) (87.0) (12.8) (4.3)
b
Cook Medical, Bloomington, Ind. W. L. Gore and Assoc, Flagstaff, Ariz. c Medtronic, Minneapolis, Minn.
Fig 1. Kaplan-Meier survival for patients who underwent stent graft therapy for dissection-related aneurysmal degeneration (DRAD) of the descending thoracic aorta (DTA).
replacements and elephant trunk procedures, and thus had proximal landing zones for stent graft therapy in surgical grafts. The other two patients with connective tissue disease presented with DeBakey III dissections and were not deemed candidates for open repair. Further patient demographic and preoperative characteristics are listed in Table I. Dissection characteristics. The mean time between the diagnosis of the aortic dissection and the stent graft procedure was 53.8 6 50.1 months. The dissections did not extend below the diaphragm (DeBakey IIIa dissection) in two patients and extended below the diaphragm (DeBakey IIIb dissection) in the remaining 45 patients. Of the 45 patients with DeBakey IIIb dissections, four patients (8.9%) had no visceral or renal vessels off the false lumen, 26 (57.8%) had one visceral or renal vessel off the false lumen, and 15 (33.3%) had two or more visceral or renal vessels off the false lumen. In 12 patients, the superior mesenteric artery (n ¼ 5), celiac artery (n ¼ 4), and one of the renal arteries (n ¼ 3) was supplied by both the true and false lumen. In 27 patients (57.4%), the extent of DRAD was limited to the proximal DTA. In 10 patients (21.3%), the DRAD, defined as total aortic diameter, including the true and false lumens, was >4 cm and involved the DTA and upper abdominal aorta. Operative details. Coverage of the proximal entry tear was achieved in 46 of 47 patients (97.9%) at the initial procedure. Postoperative chest pain developed in one patient, who was returned to the operating room. A type Ia endoleak was found, and a stent graft was placed proximally. The left subclavian artery was covered in 23 patients (48.9%) and was revascularized in 20 of these patients (87.0%), consisting of a carotid-subclavian bypass (n ¼ 16) or a carotid-subclavian transposition (n ¼ 4). Spinal drains were used in 35 patients (74.5%). Stent graft coverage extended the entire length of the DTA in 37 patients (78.7%). Further operative details are highlighted in Table II.
Perioperative outcomes. The 30-day mortality was 4.3% (n ¼ 2), which included one patient with a ruptured aneurysm. Spinal cord ischemia developed in three patients (6.4%); the lower extremity weakness resolved in two and improved in one. A cerebrospinal fluid drain was not placed preoperatively in one patient with spinal cord ischemia. Cerebrospinal fluid drains were placed preoperatively in the other two patients, and they underwent left subclavian artery revascularization before coverage. Additional neurologic events occurred in three patients (6.4%), consisting of a transient ischemic attack in one and embolic stroke in two, one of whom had permanent disability. Three patients (6.4%) sustained acute kidney injury. No patient required dialysis, and no acute kidney injury developed due to malperfusion of a renal artery off the false lumen. Two access complications (4.3%) required additional interventions. There were no retrograde aortic dissections. Intestinal malperfusion developed postoperatively in one patient in whom both the superior mesenteric artery and celiac artery arose from the false lumen and in whom the false lumen ended below the superior mesenteric artery ostium. This patient was returned emergently to the operating room, and fenestration of the septum with stenting into the superior mesenteric artery was performed. This patient had no further complications. There were no other cases of malperfusion of visceral arteries off the false lumen. Follow-up and midterm outcomes. The mean clinical follow-up was 35.1 6 20.1 months. Two patients were lost to follow-up. The mean radiographic follow-up was 30.9 6 17.8 months. In addition to the two patients above, two additional patients lacked radiographic followup. The 1-year mortality was 8.5% (n ¼ 4). One patient died at 2 months of unknown causes, and one patient died at 5 months during an SAI. The 5-year Kaplan-Meier survival was 89% 6 5% (Fig 1). Treatment failure occurred in 18 patients (38.3%): 9 required SAI, 6 did not have thrombosis of the false lumen in the area of DRAD DTA, and 4 died, including 1 death
a
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Fig 2. Kaplan-Meier analysis for freedom from treatment failure for patients who underwent stent graft therapy for dissectionrelated aneurysmal degeneration (DRAD) of the descending thoracic aorta (DTA).
during an SAI. The nine SAIs (20.0%) were performed at a mean of 10.8 6 8.1 months. The primary indication for SAI was continued aneurysmal degeneration of the upper abdominal aorta in 5 patients, which was treated with three debranching procedures, followed by stent graft coverage, 1 fenestrated endovascular aneurysm repair, and 1 extent IV thoracoabdominal aortic aneurysm repair. Three of these five patients had upper abdominal aortic diameters $4 cm but did not yet meet criteria for repair at the time of the index stent graft therapy; two of these patients had connective tissue disease. Another patient, who had progressive aneurysmal degeneration of the upper abdominal aorta requiring an SAI, underwent a prophylactic septal fenestration during the stent graft procedure to prevent renal malperfusion of a renal artery that arose from the false lumen. The patient who underwent extent IV thoracoabdominal aortic aneurysm repair as an SAI died during the operation 5 months after stent graft therapy. In the other 4 patients who underwent SAIs, the primary indication for intervention was continued aneurysmal degeneration of the DTA, which was treated with coil embolization of a type II endoleak from the subclavian artery (n ¼ 2) and coil and plug embolization of the distal thoracic false lumen (n ¼ 2). Aside from the intraoperative death during the extent IV thoracoabdominal aortic aneurysm repair, no other perioperative morbidities or deaths were related to SAIs, and the rest of the patients who underwent SAI were alive at the last follow-up. Of the six patients (14.8%) who did not have thrombosis of the DRAD DTA, four have stable aneurysms in the setting of retrograde pressurization of the thoracic aortic false lumen from fenestrations in the abdominal aorta or type II endoleaks from intercostal arteries and are being monitored; two have enlarging aneurysms but have refused further intervention. One of these latter patients had a history of renal insufficiency and underwent prophylactic fenestration of the abdominal dissection septum to prevent malperfusion of a renal artery off the false lumen. The 5year freedom from treatment failure was 54% 6 9% (Fig 2). Neither number of side branches off the false lumen nor preoperative volume predicted treatment failure (Fig 3).
Fig 3. Mean preoperative volume of the true and false lumens by treatment status in the (a) abdominal aorta and (b) descending thoracic aorta (DTA). NS, Not significant. Box-and-whisker plot: The horizontal line in the box indicates the median; the top and bottom borders of the box mark the 75th and 25th percentiles, respectively, and the whiskers mark the 90th and 10th percentiles.
Including the nine patients who underwent SAIs, treatment success was achieved in 85.2%. An example of favorable remodeling after stent graft therapy for DRAD DTA is demonstrated in Fig 4. Only one patient, who had a DeBakey IIIb dissection with all visceral and renal arteries off the true lumen, had complete thrombosis of the entire false lumen. The 34 patients who had renal arteries off the false lumen did not have deterioration of renal function from preoperatively to last clinical follow-up (1.1 6 0.6 vs 1.1 6 0.3; P ¼ .69). Connective tissue disease patients. Seven patients with connective tissue disease were treated with stent graft therapy for DRAD DTA: 3 underwent an SAI, treatment was successful in 3, and 1 was lost to follow-up. Two of the three patients who underwent an SAI for progressive upper abdominal aortic aneurysmal degeneration had upper abdominal aortic diameters $4 cm at the time of stent graft therapy. The DRAD in the three patients with treatment success was limited to the proximal DTA; in two of these three patients, stent grafts were landed in previously placed surgical grafts. DISCUSSION This single-center experience with stent graft therapy for chronic DRAD DTA is consistent with previous reports
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Fig 4. Left, Perfusion of the dissection-related aneurysmal degeneration (DRAD) in the descending thoracic aorta (DTA) prior to stent graft therapy. Right, Thrombosis of the DRAD DTA with decrease in the size of DRAD DTA after stent graft therapy.
from other high-volume institutions.3-8 Thrombosis of the false lumen in the area of the DRAD DTA with stability or decrease in the maximum diameter of the DRAD DTA can be achieved in most patients with acceptable rates of perioperative morbidity and mortality and SAI. Similar to other single-center studies, a not insignificant proportion of patients experience treatment failure, highlighting the need to identify predictors of suboptimal outcomes. Retrograde aortic dissection appears to occur more frequently with stent graft therapy for dissections than other DTA pathology.8 In a recent study using the Medtronic Thoracic Endovascular Registry, the incidence of retrograde aortic dissection with chronic dissection was 3%, compared with <1% with degenerative aneurysms. Stent graft oversizing predicted an increased risk of retrograde aortic dissection. Neither proximal stent graft configuration nor proximal landing zone appeared to affect this outcome.8 There were no retrograde aortic dissections in the present study. Refraining from excessive oversizing may be beneficial in minimizing the risk of retrograde aortic dissection. The rate of spinal cord ischemia in the current study compares well with rates reported in other single-center studies. Scali et al5 reported a 10% rate of spinal cord ischemia with stent graft therapy for chronic type B dissections with aneurysmal degeneration. However, this was before the implementation of a protocol of routine cerebrospinal fluid
drainage and left subclavian artery revascularization. After these modifications, there were no cases of spinal cord ischemia in their experience.5 The routine use of cerebrospinal fluid drainage and left subclavian artery revascularization may mitigate the incidence of this devastating complication. Stent graft therapy for DRAD DTA appears to have a lower rate of 30-day mortality and perioperative complications than open repair. Open surgery has been associated with 30-day mortality rates of 10% and acute kidney injury rates of w10%, with half of these patients requiring dialysis at discharge.3,7 One advantage of open repair may be improved freedom from reoperation. Estrera et al4 reported a 5-year freedom from reintervention on previously uninvolved aortic segments of 98%. By replacing, as opposed to excluding, dissected aorta in the DTA, the authors argue that open repair prevents retrograde pressurization of the false lumen and thus further DRAD.4 Open repair also avoids maneuvers, such as balloon angioplasty and wire manipulations, that may increase the size of fenestrations and, as a result, pressurization of the false lumen. Although the risk of reintervention for progression of aneurysmal disease in previously uninvolved aortic segments may be increased with stent graft therapy for DRAD DTA, this risk must be weighed against the increased perioperative morbidity and mortality associated with open repair. An SAI rate of 20% is higher than that seen with other pathologies of the DTA10 but is consistent with other
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single-center studies of stent graft therapy for DRAD DTA.5 There are several factors to consider when interpreting the reintervention rate of the current study. First, the SAI rate in the present study includes three patients whose upper abdominal aortic diameters were $4 cm at the time of stent graft therapy for DRAD DTA, two of whom had connective tissue disease. Second, prophylactic embolization of the left subclavian artery after carotid-subclavian bypass to prevent type II endoleak is not routinely performed at our center. Lastly, two patients underwent prophylactic fenestration of the dissection septum to prevent renal malperfusion of a renal artery arising from the false lumen. Fenestrating the abdominal aorta creates larger entry tears with subsequent increased perfusion of the abdominal aortic false lumen. Several studies have demonstrated that a larger tear size contributes to worse outcomes.11,12 When considering prophylactic fenestration in the abdominal aorta to prevent renal malperfusion, the risk of accelerating aneurysmal degeneration by creating larger entry tears must be weighed against the benefits of preventing renal function deterioration and hypertension.13 In the present study, there did not appear to be a deterioration in renal functionda surrogate for renal malperfusiondin patients with a renal artery off the false lumen after stent graft therapy for DRAD DTA. The importance of side branches of the false lumen in chronic DRADT DTA may lie in the continued perfusion and aneurysmal degeneration of the false lumen and not in an increased risk of malperfusion.9 Although stent graft therapy for DRAD DTA remains an emerging treatment alternative to open surgery, a number of single-center studies are now in the literature,3-6,14-18 with considerable variation across these studies. One salient difference in our experience appears to be a low number of patients with DeBakey IIIa dissections.3,18 This distinction carries prognostic importance, because patients with DeBakey IIIa dissections appear to have higher rates of false lumen thrombosis.3,18 An additional characteristic of the present study is that a significant number of visceral and renal vessels arose from the false lumen. The current experience had a study population in which 90% of the patients had at least one visceral or renal vessel off the false lumen, and almost one-third of patients had two or more side branches of the abdominal aorta. In a multicenter study that examined patients with acute and chronic type B aortic dissections managed with stent graft therapy, a side branch origin off the false lumen predicted failure to achieve false lumen thrombosis.9 One reason our study did not demonstrate a similar result is that it included only patients with chronic dissections. Lastly, seven patients who had connective tissue disease were included in the current study. Similar to the study from Kitagawa et al,19 which included six patients with connective tissue disease who underwent endovascular repair of chronic DTA dissections with thoracoabdominal aneurysms, most of our patients with connective tissue disease had previous proximal aortic repairs in which to deploy stent grafts.19 The gold standard in patients with DRAD
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DTA and connective tissue disease remains open repair; however, in patients who are not candidates for open repair, stent graft therapy remains an alternative to medical management of a disease process that may have as high as a 30% incidence of rupture.1 Given the concerns of failure to achieve false lumen thrombosis and for need of an SAI after stent graft therapy for DRAD DTA, predictors of treatment failure are desirable. Although dissection extent and origin of the side branches off the false lumen might predict failure to achieve false lumen thrombosis, more rational means of predicting success may be helpful. Biomechanical modeling with computational fluid dynamics appears well suited to this task. Several groups have demonstrated that computational fluid dynamics can predict DRAD DTA.20,21 Moreover, computational studies have demonstrated that proximal entry tear coverage reduces pressurization of the false lumen.22 Biomechanical study of false lumen pressure after stent graft therapy for DRAD DTA may improve the ability to predict treatment failure. The present study has several limitations. The first is selection bias, because neither patients who underwent open surgery nor patients who were not offered interventions were included. A second limitation is the absence of longitudinal, long-term follow-up and the absence of any follow-up in several patients. Despite this limitation, the mean follow-up of this study was 3 years, which compares well with that of other studies. An additional limitation is that the cohort size of 47 patients may be underpowered to demonstrate meaningful associations among the preoperative predictors and postoperative outcomes. Lastly, outcomes after stent graft therapy for DRAD DTA have not been rigorously defined. Many of these limitations promise to be addressed by the Vascular Quality Initiative TEVAR Aortic Dissection Device Surveillance Project. CONCLUSIONS In this single-center experience, stent graft therapy appears to be a safe and effective treatment in the management of chronic DRAD DTA. Including a 20% SAI rate, treatment success, defined as thrombosis of the false lumen in the area of DRAD DTA with stability or decrease in the maximum diameter of the DRAD DTA, was achieved in 85% of patients. Given an almost 40% rate of treatment failure at midterm follow-up, close clinical surveillance is warranted, and predictors of treatment failure are needed. The role of stent graft therapy in DRAD DTA in patients with connective tissue disease also requires further evaluation. AUTHOR CONTRIBUTIONS Conception and design: DN, SS, GT, BS Analysis and interpretation: DN, SS, GT, MS Data collection: DN, SS, GT Writing the article: DN, GT, BS Critical revision of the article: DN, SS, GT, MS, EV, NT, GA, BS
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Final approval of the article: DN, SS, GT, MS, EV, NT, GA, BS Statistical analysis: DN Obtained funding: Not applicable Overall responsibility: BS
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REFERENCES 1. Winnerkvist A, Lockowandt U, Rasmussen Radegran K. A prospective study of medically treated acute type B aortic dissection. Eur J Vasc Endovasc Surg 2006;32:349-55. 2. Durham CA, Cambria RP, Wang LJ, Ergul EA, Aranson NJ, Patel, VI, et al. The natural history of medically managed acute type B aortic dissection. Paper presented at: Society for Vascular Surgery 2014 Vascular Annual Meeting, Boston, MA; June 4-7, 2014. 3. Leshnower BG, Szeto WY, Pochettino A, Desai ND, Moeller PJ, Nathan DP, et al. Thoracic endografting reduces morbidity and remodels the thoracic aorta in DeBakey III aneurysms. Ann Thorac Surg 2013;95:914-21. 4. Estrera AL, Sandhu H, Afifi RO, Azizzadeh A, Charlton-Ouw K, Miller CC, et al. Open repair of chronic complicated type B aortic dissection using the open distal technique. Ann Cardiothorac Surg 2014;3:375-84. 5. Nathan DP, Woo EY, Fairman RM, Wang GJ, Pochettino A, Desai ND, et al. Stent grafting for aneurysmal degeneration of chronic descending thoracic aortic dissections. J Vasc Surg 2012;55:963-7. 6. Scali ST, Feezor RJ, Chang CK, Stone DH, Hess PJ, Martin TD, et al. Efficacy of thoracic endovascular stent repair for chronic type B aortic dissection with aneurysmal degeneration. J Vasc Surg 2013;58:10-7. 7. Andacheh ID, Donayre C, Othman F, Walot I, Kopchok G, White R. Patient outcomes and thoracic aortic volume and morphologic changes following thoracic endovascular aortic repair in patients with complicated chronic type B aortic dissection. J Vasc Surg 2012;56:644-50. 8. Canaud L, Ozdemir BA, Patterson BO, Holt PJ, Loftus IM, Thompson MM. Retrograde aortic dissection after thoracic endovascular aortic repair. Ann Surg 2014;260:389-95. 9. Tolenaar JL, Kern JA, Jonker FK, Cherry KJ, Tracci MC, Angle JF, et al. Predictors of false lumen thrombosis in type B aortic dissection treated with TEVAR. Ann Cardiothorac Surg 2014;3:255-63. 10. Scali ST, Beck AW, Butler K, Feezor RJ, Martin TD, Hess PJ, et al. Pathology-specific secondary aortic interventions after thoracic endovascular aortic repair. J Vasc Surg 2014;59:599-607. 11. Evangelista A, Salas A, Ribera A, Ferreira-Gonzalez I, Cuellar H, Pineda V, et al. Long-term outcome of aortic dissection with patent
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false lumen: predictive role of entry tear size and location. Circulation 2012;125:3133-41. Rudenick PA, Bijnens BH, Garcia-Dorado D, Evangelista A. An in vitro phantom study on the influence of tear size and configuration on the hemodynamics of the lumina in chronic type B aortic dissections. J Vasc Surg 2013;57:464-74. Suzuki T, Isselbacher EM, Nienaber CA, Pyeritz RE, Eagle KA, Tsai TT, et al. Type-selective benefits of medications in treatment of acute aortic dissection (from the International Registry of Acute Aortic Dissection [IRAD]). Am J Cardiol 2012;109:122-7. Parsa CJ, Schroder JN, Daneshmand MA, McCann RL, Hughes GC. Midterm results for endovascular repair of complicated acute and chronic type B aortic dissection. Ann Thorac Surg 2010;89:97-102. Czerny M, Roedler S, Fakhimi S, Sodeck G, Funovics M, Dumfarth J, et al. Midterm results of thoracic endovascular aortic repair in patients with aneurysms involving the descending aorta originating from chronic type B dissections. Ann Thorac Surg 2010;90:90-4. Xu SD, Huang FJ, Yang JF, Li ZZ, Yang S, Du JH, et al. Early and midterm results of thoracic endovascular aortic repair of chronic type B aortic dissection. J Thorac Cardiovasc Surg 2010;139: 1548-53. Manning BJ, Dias N, Ohrlander T, Malina M, Sonesson B, Resch T, et al. Endovascular treatment for chronic type B dissection: limitations of short stent-grafts revealed at midterm follow-up. J Endovasc Ther 2009;16:590-7. Rodriguez JA, Olsen DM, Lucas L, Wheatley G, Ramaiah V, Diethrich EB. Aortic remodeling after endografting of thoracoabdominal aortic dissection. J Vasc Surg 2008;47:1188-94. Kitagawa A, Greenberg RK, Eagleton MJ, Mastracci TM, Roselli EE. Fenestrated and branched endovascular aortic repair for chronic type B aortic dissection with thoracoabdominal aneurysms. J Vasc Surg 2013;58:625-34. Karmonik C, Partovi S, Muller-Eschner M, Bismuth J, Davies MG, Shah DJ, et al. Longitudinal computational fluid dynamics study of aneurysmal dilatation in a chronic DeBakey type III aortic dissection. J Vasc Surg 2012;56:260-3. Shank EK, Nathan DP, Fairman RM, Bavaria JE, Gorman RC, Gorman JH, et al. BM. Use of computational fluid dynamics studies in predicting aneurysmal degeneration of acute type B aortic dissections. Poster presented at: Society for Vascular Surgery 2014 Vascular Annual Meeting, Boston, MA; June 4-7, 2014. Karmonik C, Bismuth J, Shah DJ, Davies MG, Purdy D, Lumsden AB. Computational study of haemodynamic effects of entry- and exit-tear coverage in a DeBakey type III aortic dissection: technical report. Eur J Vasc Endovasc Surg 2011;42:172-7.
Submitted Oct 20, 2014; accepted Dec 8, 2014.
DISCUSSION Dr Carlos E. Donayre (Rancho Palos Verdes, Calif). INSTEAD for uncomplicated descending thoracic dissections at 5 years has demonstrated a trend towards reduction in all-cause mortality vs optimal medical therapy, a 19.1% absolute risk reduction in disease progression (46% to 27%), and a mortality three times higher with optimal medical therapy. Our experience with TEVAR for complicated descending thoracic dissection demonstrated a 14% all-cause mortality at 30 days, and 15% required a secondary procedure for endoleak or persistent distal perfusion. Dr Nathan and coauthors present a single center retrospective study of 47 patients who underwent stent-graft therapy for type B dissection with aneurysmal degeneration. Forty-three (91%) of the procedures were performed electively for aneurysm size $5.5 cm (n ¼ 35) or aneurysm expansion $0.5 cm over a 6-month period (n ¼ 8). Additionally, four procedures were performed emergently or urgently for symptoms or rupture. The 30-day mortality for these patients was only 4%, which included a patient who presented with rupture.
Approximately 20% had secondary aortic interventions performed for continued aneurysmal degeneration of the upper abdominal aorta in five patients, and continued aneurysmal degeneration of the descending thoracic aorta in 4 patients. Freedom from treatment failure, which was defined as allcause death, need for secondary aortic intervention, and failure to achieve thrombosis of the dissection related aneurysmal degeneration in the descending thoracic aorta (DRAD DTA) was 54% at 5 years by Kaplan-Meier analysis. I have the following questions: What was the extent of aortic coverage in your patients, left CCA to celiac artery (which is what we do), or did you just cover the initial tear? Dr Derek P. Nathan. Initially, the main goal of therapy was only to cover the primary entry tear; however, this approach has evolved to favor coverage of the entire descending thoracic aorta. The left subclavian artery was covered in 23 of the 47 patients, and was revascularized in 20 of these 23. Dr Donayre. You measured false and true volumes after TEVAR, and did not find them useful, however after secondary
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interventions the false lumen volume was reduced in 85% of these patients, how do you explain this? Dr Nathan. The preoperative volume of the true and false lumen in the descending thoracic and abdominal aorta was measured. The postoperative volume of the descending thoracic and abdominal aorta was not measured. Postoperative thrombosis of the DRAD DTA was determined through examination of patients’ last postoperative CTA, including arterial and delayed imaging. The diameter at the point of maximal DRAD DTA was measured on patients’ preoperative and last postoperative CTA. Including the nine patients who underwent secondary aortic interventions, treatment success, which was defined as thrombosis of the false lumen in the area of DRAD DTA with stability or decrease in the maximum diameter of the DRAD DTA on the last postoperative CTA, was achieved in 85.2% of patients. Dr Donayre. Could you elaborate on your CTD patients, you achieved false lumen thrombosis in three and three had
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secondary interventions, what is the follow-up of these patients with regard to persistent false lumen thrombosis? Should they be treated until FL thrombosis is achieved to avoid late death due to rupture in these very challenging patients? Dr Nathan. Of the seven patients with connective tissue disease treated with stent-graft therapy for DRAD DTA, three underwent SAI, three had treatment success, and one was lost to follow-up. Two of the three patients who underwent SAI for progressive upper abdominal aortic aneurysmal degeneration had upper abdominal aortic diameters $4 cm at the time of stent-graft therapy. The three patients with treatment success had DRAD limited to the proximal descending thoracic aorta. The goal of therapy in all patients is thrombosis of the DRAD DTA. Patient with connective tissue disease can be particularly susceptible to continued aneurysmal degeneration of the false lumen and require close clinical follow-up.
Outcomes after stent graft therapy for dissection-related aneurysmal degeneration in the descending thoracic aorta Derek P. Nathan, MD,a Sherene Shalhub, MD, MPH,a Gale L. Tang, MD,a Matthew P. Sweet, MD,a Edward D. Verrier, MD,b Nam T. Tran, MD,a Gabriel S. Aldea, MD,b and Benjamin W. Starnes, MD,a Seattle, Wash Objective: Stent graft therapy has emerged as an alternative to open surgery in the management of chronic dissectionrelated aneurysmal degeneration (DRAD) in the descending thoracic aorta (DTA). The incidence of perioperative complications, need for secondary aortic intervention (SAI), and rate of aneurysmal false-lumen thrombosis have not been thoroughly described. Methods: Perioperative and midterm outcomes in patients who underwent stent graft therapy for chronic DRAD DTA at a single institution between January 2006 and September 2013 were retrospectively analyzed. Preoperative anatomic factors, including the number of visceral and renal side branches off the false lumen, and false lumen volume, were analyzed for their ability to predict treatment failure. Treatment failure was defined as death, need for a SAI, and failure to achieve thrombosis of the DRAD DTA. Treatment success was defined as thrombosis of the false lumen in the area of the DRAD DTA with stability or a decrease in the maximum diameter of the DRAD DTA. Results: During the study period, 47 patients underwent stent graft therapy for chronic DRAD DTA. Patients were a mean age of 58.3 6 11.7 years, 74.5% (n [ 35) were male, and 14.9% (n [ 7) had a history of connective tissue disease. The left subclavian artery was covered in 48.9% (n [ 23), and revascularization was performed in 87.0% (n [ 20). Spinal drains were used in 74.5% (n [ 35). Spinal cord ischemia developed in 6.4% (n [ 3), which resolved in two and improved in one. No retrograde aortic dissections occurred. The 30-day mortality was 4.3% (n [ 2); one death was in a patient with rupture. Mean clinical follow-up was 35.1 6 20.9 months. The 5-year Kaplan-Meier survival was 89% 6 5%. Treatment failure occurred in 18 patients (38.3%): 9 required SAIs, 6 did not have thrombosis of the false lumen in the area of the DRAD DTA, and 4 died, with 1 patient dying during a SAI. No preoperative anatomic factor predicted treatment failure. The 5-year freedom from treatment failure was 54% 6 9%. Including the nine patients who underwent SAI, treatment success was achieved in 85.2% of patients. Conclusions: In this single-center experience of stent graft therapy for chronic DRAD DTA, treatment success was achieved in 85% of patients after a SAI rate of 20%. No preoperative anatomic factor predicted treatment failure, which occurred in almost 40% of the patients. Identifying predictors of treatment failure may improve future outcomes. (J Vasc Surg 2015;61:1200-7.)
Dissection-related aneurysmal degeneration (DRAD) in the descending thoracic aorta (DTA) occurs in 20% of medically managed uncomplicated acute type B dissections, and it has been associated with a >30% incidence of rupture once the DRAD DTA is >6 cm.1 A recent study of medical management of acute uncomplicated From the Divisions of Vascular Surgerya and Cardiac Surgery,b University of Washington. Author conflict of interest: none. Presented at the Twenty-ninth Annual Meeting of the Western Vascular Society, Coronado, Calif, September 20-23, 2014. Reprint requests: Benjamin W. Starnes, MD, University of Washington/ Harborview Medical Center, 325 9th Ave, Box 359908, Seattle, WA 98104 (e-mail: [email protected]). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2015 by the Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jvs.2014.12.040
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type B dissections reported a 60% failure rate, which was defined as subsequent need for aortic intervention or death.2 Open surgical repair of chronic DRAD DTA carries significant risks, including a 30-day mortality of 10%, and rates of paraplegia, renal failure, and pulmonary failure of 10%.3,4 Stent graft therapy has emerged as an alternative to open surgery, with low rates of perioperative morbidity and mortality and high rates of false lumen thrombosis.3,5-8 Although stent graft therapy for DRAD DTA appears promising, retrograde aortic dissection, spinal cord ischemia, and the need for secondary aortic intervention (SAI) have been identified as areas of concern.6,8 Given these concerns, identifying predictors of suboptimal outcomes after stent graft therapy for chronic DRAD DTA is an important area of investigation. Previous work has identified false lumen volume and number of side branches off the false lumen as preoperative determinants that have a potential affect on postoperative outcomes.7,9
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This study investigated a single-center experience with stent graft therapy for chronic DRAD DTA and sought to identify predictors of treatment failure. We hypothesized that preoperative anatomic factors, including false lumen volume and number of renal and visceral vessels arising from the false lumen, would predict treatment failure.9 METHODS This study was conducted with the approval of the University of Washington Human Research Ethics Committee. The need for informed consent from the patients was waived. Study cohort. A retrospective study was performed of patients who underwent stent graft therapy for chronic DRAD DTA between January 2006 and September 2013 at a single institution. Chronic DRAD DTA was defined by the presence of aortic dissection for >2 weeks.7 Clinical practice. All patients underwent fine-cut computed tomography angiography (CTA) to assist with planning of the stent graft procedure. Initially, the main goal of therapy was to cover the primary entry tear; however, this approach evolved to favor coverage of the entire DTA. Intravascular ultrasound imaging was used in all cases to confirm wire position in the true lumen and assist with sizing of the stent graft. Stent grafts were oversized by w10% to 15% according to the diameter of the normal aorta in the proximal landing zone. With respect to the distal landing zone, sizing was to the diameter of the true and false lumen. If the true lumen was narrowed significantly distally, a tapered stent graft was used. Balloon angioplasty of the proximal and distal landing zone was not routinely performed. At the start of the study period, revascularization of the left subclavian artery was performed at the discretion of the surgeon. However, left subclavian artery revascularization is now routine. Management of visceral or renal vessels that arose from the false lumen was at the surgeon’s discretion. Aortic analysis and volume measurements. Preoperative CTA scans were analyzed on an Aquarius iNtuition workstation (TeraRecon, San Mateo, Calif). The luminal origin of the renal arteries, superior mesenteric artery, and celiac artery was determined. The origin of the inferior mesenteric artery and common iliac arteries was not evaluated. A vessel that arose from both the true and false lumen was classified as arising from the false lumen. The preoperative volume of the true and false lumen in the DTA and abdominal aorta was measured using a semiautomatic segmentation method by one of the authors (D.P.N.). In brief, a centerline was created in the true and false lumen, and the area of each orthogonal CTA cut was measured. Flow lumen and thrombus were both included in the measurements. The DTA was defined as the left subclavian artery to the celiac artery, and the abdominal aorta was defined as the celiac artery to the aortic bifurcation. The postoperative volume of the DTA and abdominal aorta was not measured. Thrombosis of the false lumen was determined through examination of the patient’s last postoperative
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Table I. Preoperative characteristics of patients undergoing stent graft therapy for dissection-related aneurysmal degeneration (DRAD) of the descending thoracic aorta (DTA) Feature Age, years Male Hypertension Previous aortic operation Type A dissection repair Aortic arch repair (including debranching procedures) Abdominal aortic aneurysm repair Indication for intervention Aneurysm size $5.5 cm Aneurysm expansion $0.5 cm over 6 months Refractory chest pain Rupture
Mean 6 SD or No. (%) 58.3 6 11.7 35 (74.5) 41 (87.2) 13 (27.7) 8 (17.0) 8 (17.0) 35 (74.5) 8 (17.0) 2 (4.3) 2 (4.3)
SD, Standard deviation.
CTA, including arterial and delayed imaging. The diameter at the point of maximal DRAD DTA was measured on the patient’s preoperative and last postoperative CTA. If no treatment failure occurred, follow-up imaging consisted of a CTA with arterial and delayed imaging at 1 month and annually thereafter. Study outcomes and statistical analysis. Study outcomes included perioperative morbidity and mortality, midterm survival, and treatment failure and success. Treatment failure was a composite, including aortic-related and nonaortic-related death, need for SAI, and failure to achieve thrombosis of the false lumen in the area of the DRAD DTA. Criteria for treatment success included thrombosis of the false lumen in the area of the DRAD DTA, with stability or a decrease in the maximum diameter of the DRAD DTA. The number of renal and visceral arteries off the false lumen and the preoperative volume of the true and false lumens in the DTA and the abdominal aorta were analyzed for their ability to predict treatment failure. These variables were selected on the basis of a previous investigation and to focus on the potential identification of preoperative anatomic predictors of treatment failure.9 Statistical analysis was performed with GraphPad Prism software (GraphPad Software Inc, La Jolla, Calif). Univariate analysis with c2 test, paired t-test, and Mann-Whitney U test was performed, as appropriate. Survival and freedom from treatment failure were determined using Kaplan-Meier analysis. RESULTS During the study period, 47 patients underwent stent graft therapy for chronic DRAD DTA. Seven patients (14.9%) had connective tissue disease; five (71.4%) of these patients had previously undergone repair of type A dissections, followed by arch debranching procedures or arch
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Table II. Operative details of patients undergoing stent graft therapy for dissection-related aneurysmal degeneration (DRAD) of the descending thoracic aorta (DTA) Feature Stent graft TX2a TAGb Talentc Cerebrospinal fluid drainage Left subclavian artery Coverage Revascularization Visceral or renal stent Abdominal debranching plus stent graft procedure
No (%) 40 4 3 35
(85.1) (8.5) (6.4) (74.5)
23 20 6 2
(48.9) (87.0) (12.8) (4.3)
b
Cook Medical, Bloomington, Ind. W. L. Gore and Assoc, Flagstaff, Ariz. c Medtronic, Minneapolis, Minn.
Fig 1. Kaplan-Meier survival for patients who underwent stent graft therapy for dissection-related aneurysmal degeneration (DRAD) of the descending thoracic aorta (DTA).
replacements and elephant trunk procedures, and thus had proximal landing zones for stent graft therapy in surgical grafts. The other two patients with connective tissue disease presented with DeBakey III dissections and were not deemed candidates for open repair. Further patient demographic and preoperative characteristics are listed in Table I. Dissection characteristics. The mean time between the diagnosis of the aortic dissection and the stent graft procedure was 53.8 6 50.1 months. The dissections did not extend below the diaphragm (DeBakey IIIa dissection) in two patients and extended below the diaphragm (DeBakey IIIb dissection) in the remaining 45 patients. Of the 45 patients with DeBakey IIIb dissections, four patients (8.9%) had no visceral or renal vessels off the false lumen, 26 (57.8%) had one visceral or renal vessel off the false lumen, and 15 (33.3%) had two or more visceral or renal vessels off the false lumen. In 12 patients, the superior mesenteric artery (n ¼ 5), celiac artery (n ¼ 4), and one of the renal arteries (n ¼ 3) was supplied by both the true and false lumen. In 27 patients (57.4%), the extent of DRAD was limited to the proximal DTA. In 10 patients (21.3%), the DRAD, defined as total aortic diameter, including the true and false lumens, was >4 cm and involved the DTA and upper abdominal aorta. Operative details. Coverage of the proximal entry tear was achieved in 46 of 47 patients (97.9%) at the initial procedure. Postoperative chest pain developed in one patient, who was returned to the operating room. A type Ia endoleak was found, and a stent graft was placed proximally. The left subclavian artery was covered in 23 patients (48.9%) and was revascularized in 20 of these patients (87.0%), consisting of a carotid-subclavian bypass (n ¼ 16) or a carotid-subclavian transposition (n ¼ 4). Spinal drains were used in 35 patients (74.5%). Stent graft coverage extended the entire length of the DTA in 37 patients (78.7%). Further operative details are highlighted in Table II.
Perioperative outcomes. The 30-day mortality was 4.3% (n ¼ 2), which included one patient with a ruptured aneurysm. Spinal cord ischemia developed in three patients (6.4%); the lower extremity weakness resolved in two and improved in one. A cerebrospinal fluid drain was not placed preoperatively in one patient with spinal cord ischemia. Cerebrospinal fluid drains were placed preoperatively in the other two patients, and they underwent left subclavian artery revascularization before coverage. Additional neurologic events occurred in three patients (6.4%), consisting of a transient ischemic attack in one and embolic stroke in two, one of whom had permanent disability. Three patients (6.4%) sustained acute kidney injury. No patient required dialysis, and no acute kidney injury developed due to malperfusion of a renal artery off the false lumen. Two access complications (4.3%) required additional interventions. There were no retrograde aortic dissections. Intestinal malperfusion developed postoperatively in one patient in whom both the superior mesenteric artery and celiac artery arose from the false lumen and in whom the false lumen ended below the superior mesenteric artery ostium. This patient was returned emergently to the operating room, and fenestration of the septum with stenting into the superior mesenteric artery was performed. This patient had no further complications. There were no other cases of malperfusion of visceral arteries off the false lumen. Follow-up and midterm outcomes. The mean clinical follow-up was 35.1 6 20.1 months. Two patients were lost to follow-up. The mean radiographic follow-up was 30.9 6 17.8 months. In addition to the two patients above, two additional patients lacked radiographic followup. The 1-year mortality was 8.5% (n ¼ 4). One patient died at 2 months of unknown causes, and one patient died at 5 months during an SAI. The 5-year Kaplan-Meier survival was 89% 6 5% (Fig 1). Treatment failure occurred in 18 patients (38.3%): 9 required SAI, 6 did not have thrombosis of the false lumen in the area of DRAD DTA, and 4 died, including 1 death
a
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Fig 2. Kaplan-Meier analysis for freedom from treatment failure for patients who underwent stent graft therapy for dissectionrelated aneurysmal degeneration (DRAD) of the descending thoracic aorta (DTA).
during an SAI. The nine SAIs (20.0%) were performed at a mean of 10.8 6 8.1 months. The primary indication for SAI was continued aneurysmal degeneration of the upper abdominal aorta in 5 patients, which was treated with three debranching procedures, followed by stent graft coverage, 1 fenestrated endovascular aneurysm repair, and 1 extent IV thoracoabdominal aortic aneurysm repair. Three of these five patients had upper abdominal aortic diameters $4 cm but did not yet meet criteria for repair at the time of the index stent graft therapy; two of these patients had connective tissue disease. Another patient, who had progressive aneurysmal degeneration of the upper abdominal aorta requiring an SAI, underwent a prophylactic septal fenestration during the stent graft procedure to prevent renal malperfusion of a renal artery that arose from the false lumen. The patient who underwent extent IV thoracoabdominal aortic aneurysm repair as an SAI died during the operation 5 months after stent graft therapy. In the other 4 patients who underwent SAIs, the primary indication for intervention was continued aneurysmal degeneration of the DTA, which was treated with coil embolization of a type II endoleak from the subclavian artery (n ¼ 2) and coil and plug embolization of the distal thoracic false lumen (n ¼ 2). Aside from the intraoperative death during the extent IV thoracoabdominal aortic aneurysm repair, no other perioperative morbidities or deaths were related to SAIs, and the rest of the patients who underwent SAI were alive at the last follow-up. Of the six patients (14.8%) who did not have thrombosis of the DRAD DTA, four have stable aneurysms in the setting of retrograde pressurization of the thoracic aortic false lumen from fenestrations in the abdominal aorta or type II endoleaks from intercostal arteries and are being monitored; two have enlarging aneurysms but have refused further intervention. One of these latter patients had a history of renal insufficiency and underwent prophylactic fenestration of the abdominal dissection septum to prevent malperfusion of a renal artery off the false lumen. The 5year freedom from treatment failure was 54% 6 9% (Fig 2). Neither number of side branches off the false lumen nor preoperative volume predicted treatment failure (Fig 3).
Fig 3. Mean preoperative volume of the true and false lumens by treatment status in the (a) abdominal aorta and (b) descending thoracic aorta (DTA). NS, Not significant. Box-and-whisker plot: The horizontal line in the box indicates the median; the top and bottom borders of the box mark the 75th and 25th percentiles, respectively, and the whiskers mark the 90th and 10th percentiles.
Including the nine patients who underwent SAIs, treatment success was achieved in 85.2%. An example of favorable remodeling after stent graft therapy for DRAD DTA is demonstrated in Fig 4. Only one patient, who had a DeBakey IIIb dissection with all visceral and renal arteries off the true lumen, had complete thrombosis of the entire false lumen. The 34 patients who had renal arteries off the false lumen did not have deterioration of renal function from preoperatively to last clinical follow-up (1.1 6 0.6 vs 1.1 6 0.3; P ¼ .69). Connective tissue disease patients. Seven patients with connective tissue disease were treated with stent graft therapy for DRAD DTA: 3 underwent an SAI, treatment was successful in 3, and 1 was lost to follow-up. Two of the three patients who underwent an SAI for progressive upper abdominal aortic aneurysmal degeneration had upper abdominal aortic diameters $4 cm at the time of stent graft therapy. The DRAD in the three patients with treatment success was limited to the proximal DTA; in two of these three patients, stent grafts were landed in previously placed surgical grafts. DISCUSSION This single-center experience with stent graft therapy for chronic DRAD DTA is consistent with previous reports
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Fig 4. Left, Perfusion of the dissection-related aneurysmal degeneration (DRAD) in the descending thoracic aorta (DTA) prior to stent graft therapy. Right, Thrombosis of the DRAD DTA with decrease in the size of DRAD DTA after stent graft therapy.
from other high-volume institutions.3-8 Thrombosis of the false lumen in the area of the DRAD DTA with stability or decrease in the maximum diameter of the DRAD DTA can be achieved in most patients with acceptable rates of perioperative morbidity and mortality and SAI. Similar to other single-center studies, a not insignificant proportion of patients experience treatment failure, highlighting the need to identify predictors of suboptimal outcomes. Retrograde aortic dissection appears to occur more frequently with stent graft therapy for dissections than other DTA pathology.8 In a recent study using the Medtronic Thoracic Endovascular Registry, the incidence of retrograde aortic dissection with chronic dissection was 3%, compared with <1% with degenerative aneurysms. Stent graft oversizing predicted an increased risk of retrograde aortic dissection. Neither proximal stent graft configuration nor proximal landing zone appeared to affect this outcome.8 There were no retrograde aortic dissections in the present study. Refraining from excessive oversizing may be beneficial in minimizing the risk of retrograde aortic dissection. The rate of spinal cord ischemia in the current study compares well with rates reported in other single-center studies. Scali et al5 reported a 10% rate of spinal cord ischemia with stent graft therapy for chronic type B dissections with aneurysmal degeneration. However, this was before the implementation of a protocol of routine cerebrospinal fluid
drainage and left subclavian artery revascularization. After these modifications, there were no cases of spinal cord ischemia in their experience.5 The routine use of cerebrospinal fluid drainage and left subclavian artery revascularization may mitigate the incidence of this devastating complication. Stent graft therapy for DRAD DTA appears to have a lower rate of 30-day mortality and perioperative complications than open repair. Open surgery has been associated with 30-day mortality rates of 10% and acute kidney injury rates of w10%, with half of these patients requiring dialysis at discharge.3,7 One advantage of open repair may be improved freedom from reoperation. Estrera et al4 reported a 5-year freedom from reintervention on previously uninvolved aortic segments of 98%. By replacing, as opposed to excluding, dissected aorta in the DTA, the authors argue that open repair prevents retrograde pressurization of the false lumen and thus further DRAD.4 Open repair also avoids maneuvers, such as balloon angioplasty and wire manipulations, that may increase the size of fenestrations and, as a result, pressurization of the false lumen. Although the risk of reintervention for progression of aneurysmal disease in previously uninvolved aortic segments may be increased with stent graft therapy for DRAD DTA, this risk must be weighed against the increased perioperative morbidity and mortality associated with open repair. An SAI rate of 20% is higher than that seen with other pathologies of the DTA10 but is consistent with other
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single-center studies of stent graft therapy for DRAD DTA.5 There are several factors to consider when interpreting the reintervention rate of the current study. First, the SAI rate in the present study includes three patients whose upper abdominal aortic diameters were $4 cm at the time of stent graft therapy for DRAD DTA, two of whom had connective tissue disease. Second, prophylactic embolization of the left subclavian artery after carotid-subclavian bypass to prevent type II endoleak is not routinely performed at our center. Lastly, two patients underwent prophylactic fenestration of the dissection septum to prevent renal malperfusion of a renal artery arising from the false lumen. Fenestrating the abdominal aorta creates larger entry tears with subsequent increased perfusion of the abdominal aortic false lumen. Several studies have demonstrated that a larger tear size contributes to worse outcomes.11,12 When considering prophylactic fenestration in the abdominal aorta to prevent renal malperfusion, the risk of accelerating aneurysmal degeneration by creating larger entry tears must be weighed against the benefits of preventing renal function deterioration and hypertension.13 In the present study, there did not appear to be a deterioration in renal functionda surrogate for renal malperfusiondin patients with a renal artery off the false lumen after stent graft therapy for DRAD DTA. The importance of side branches of the false lumen in chronic DRADT DTA may lie in the continued perfusion and aneurysmal degeneration of the false lumen and not in an increased risk of malperfusion.9 Although stent graft therapy for DRAD DTA remains an emerging treatment alternative to open surgery, a number of single-center studies are now in the literature,3-6,14-18 with considerable variation across these studies. One salient difference in our experience appears to be a low number of patients with DeBakey IIIa dissections.3,18 This distinction carries prognostic importance, because patients with DeBakey IIIa dissections appear to have higher rates of false lumen thrombosis.3,18 An additional characteristic of the present study is that a significant number of visceral and renal vessels arose from the false lumen. The current experience had a study population in which 90% of the patients had at least one visceral or renal vessel off the false lumen, and almost one-third of patients had two or more side branches of the abdominal aorta. In a multicenter study that examined patients with acute and chronic type B aortic dissections managed with stent graft therapy, a side branch origin off the false lumen predicted failure to achieve false lumen thrombosis.9 One reason our study did not demonstrate a similar result is that it included only patients with chronic dissections. Lastly, seven patients who had connective tissue disease were included in the current study. Similar to the study from Kitagawa et al,19 which included six patients with connective tissue disease who underwent endovascular repair of chronic DTA dissections with thoracoabdominal aneurysms, most of our patients with connective tissue disease had previous proximal aortic repairs in which to deploy stent grafts.19 The gold standard in patients with DRAD
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DTA and connective tissue disease remains open repair; however, in patients who are not candidates for open repair, stent graft therapy remains an alternative to medical management of a disease process that may have as high as a 30% incidence of rupture.1 Given the concerns of failure to achieve false lumen thrombosis and for need of an SAI after stent graft therapy for DRAD DTA, predictors of treatment failure are desirable. Although dissection extent and origin of the side branches off the false lumen might predict failure to achieve false lumen thrombosis, more rational means of predicting success may be helpful. Biomechanical modeling with computational fluid dynamics appears well suited to this task. Several groups have demonstrated that computational fluid dynamics can predict DRAD DTA.20,21 Moreover, computational studies have demonstrated that proximal entry tear coverage reduces pressurization of the false lumen.22 Biomechanical study of false lumen pressure after stent graft therapy for DRAD DTA may improve the ability to predict treatment failure. The present study has several limitations. The first is selection bias, because neither patients who underwent open surgery nor patients who were not offered interventions were included. A second limitation is the absence of longitudinal, long-term follow-up and the absence of any follow-up in several patients. Despite this limitation, the mean follow-up of this study was 3 years, which compares well with that of other studies. An additional limitation is that the cohort size of 47 patients may be underpowered to demonstrate meaningful associations among the preoperative predictors and postoperative outcomes. Lastly, outcomes after stent graft therapy for DRAD DTA have not been rigorously defined. Many of these limitations promise to be addressed by the Vascular Quality Initiative TEVAR Aortic Dissection Device Surveillance Project. CONCLUSIONS In this single-center experience, stent graft therapy appears to be a safe and effective treatment in the management of chronic DRAD DTA. Including a 20% SAI rate, treatment success, defined as thrombosis of the false lumen in the area of DRAD DTA with stability or decrease in the maximum diameter of the DRAD DTA, was achieved in 85% of patients. Given an almost 40% rate of treatment failure at midterm follow-up, close clinical surveillance is warranted, and predictors of treatment failure are needed. The role of stent graft therapy in DRAD DTA in patients with connective tissue disease also requires further evaluation. AUTHOR CONTRIBUTIONS Conception and design: DN, SS, GT, BS Analysis and interpretation: DN, SS, GT, MS Data collection: DN, SS, GT Writing the article: DN, GT, BS Critical revision of the article: DN, SS, GT, MS, EV, NT, GA, BS
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Final approval of the article: DN, SS, GT, MS, EV, NT, GA, BS Statistical analysis: DN Obtained funding: Not applicable Overall responsibility: BS
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false lumen: predictive role of entry tear size and location. Circulation 2012;125:3133-41. Rudenick PA, Bijnens BH, Garcia-Dorado D, Evangelista A. An in vitro phantom study on the influence of tear size and configuration on the hemodynamics of the lumina in chronic type B aortic dissections. J Vasc Surg 2013;57:464-74. Suzuki T, Isselbacher EM, Nienaber CA, Pyeritz RE, Eagle KA, Tsai TT, et al. Type-selective benefits of medications in treatment of acute aortic dissection (from the International Registry of Acute Aortic Dissection [IRAD]). Am J Cardiol 2012;109:122-7. Parsa CJ, Schroder JN, Daneshmand MA, McCann RL, Hughes GC. Midterm results for endovascular repair of complicated acute and chronic type B aortic dissection. Ann Thorac Surg 2010;89:97-102. Czerny M, Roedler S, Fakhimi S, Sodeck G, Funovics M, Dumfarth J, et al. Midterm results of thoracic endovascular aortic repair in patients with aneurysms involving the descending aorta originating from chronic type B dissections. Ann Thorac Surg 2010;90:90-4. Xu SD, Huang FJ, Yang JF, Li ZZ, Yang S, Du JH, et al. Early and midterm results of thoracic endovascular aortic repair of chronic type B aortic dissection. J Thorac Cardiovasc Surg 2010;139: 1548-53. Manning BJ, Dias N, Ohrlander T, Malina M, Sonesson B, Resch T, et al. Endovascular treatment for chronic type B dissection: limitations of short stent-grafts revealed at midterm follow-up. J Endovasc Ther 2009;16:590-7. Rodriguez JA, Olsen DM, Lucas L, Wheatley G, Ramaiah V, Diethrich EB. Aortic remodeling after endografting of thoracoabdominal aortic dissection. J Vasc Surg 2008;47:1188-94. Kitagawa A, Greenberg RK, Eagleton MJ, Mastracci TM, Roselli EE. Fenestrated and branched endovascular aortic repair for chronic type B aortic dissection with thoracoabdominal aneurysms. J Vasc Surg 2013;58:625-34. Karmonik C, Partovi S, Muller-Eschner M, Bismuth J, Davies MG, Shah DJ, et al. Longitudinal computational fluid dynamics study of aneurysmal dilatation in a chronic DeBakey type III aortic dissection. J Vasc Surg 2012;56:260-3. Shank EK, Nathan DP, Fairman RM, Bavaria JE, Gorman RC, Gorman JH, et al. BM. Use of computational fluid dynamics studies in predicting aneurysmal degeneration of acute type B aortic dissections. Poster presented at: Society for Vascular Surgery 2014 Vascular Annual Meeting, Boston, MA; June 4-7, 2014. Karmonik C, Bismuth J, Shah DJ, Davies MG, Purdy D, Lumsden AB. Computational study of haemodynamic effects of entry- and exit-tear coverage in a DeBakey type III aortic dissection: technical report. Eur J Vasc Endovasc Surg 2011;42:172-7.
Submitted Oct 20, 2014; accepted Dec 8, 2014.
DISCUSSION Dr Carlos E. Donayre (Rancho Palos Verdes, Calif). INSTEAD for uncomplicated descending thoracic dissections at 5 years has demonstrated a trend towards reduction in all-cause mortality vs optimal medical therapy, a 19.1% absolute risk reduction in disease progression (46% to 27%), and a mortality three times higher with optimal medical therapy. Our experience with TEVAR for complicated descending thoracic dissection demonstrated a 14% all-cause mortality at 30 days, and 15% required a secondary procedure for endoleak or persistent distal perfusion. Dr Nathan and coauthors present a single center retrospective study of 47 patients who underwent stent-graft therapy for type B dissection with aneurysmal degeneration. Forty-three (91%) of the procedures were performed electively for aneurysm size $5.5 cm (n ¼ 35) or aneurysm expansion $0.5 cm over a 6-month period (n ¼ 8). Additionally, four procedures were performed emergently or urgently for symptoms or rupture. The 30-day mortality for these patients was only 4%, which included a patient who presented with rupture.
Approximately 20% had secondary aortic interventions performed for continued aneurysmal degeneration of the upper abdominal aorta in five patients, and continued aneurysmal degeneration of the descending thoracic aorta in 4 patients. Freedom from treatment failure, which was defined as allcause death, need for secondary aortic intervention, and failure to achieve thrombosis of the dissection related aneurysmal degeneration in the descending thoracic aorta (DRAD DTA) was 54% at 5 years by Kaplan-Meier analysis. I have the following questions: What was the extent of aortic coverage in your patients, left CCA to celiac artery (which is what we do), or did you just cover the initial tear? Dr Derek P. Nathan. Initially, the main goal of therapy was only to cover the primary entry tear; however, this approach has evolved to favor coverage of the entire descending thoracic aorta. The left subclavian artery was covered in 23 of the 47 patients, and was revascularized in 20 of these 23. Dr Donayre. You measured false and true volumes after TEVAR, and did not find them useful, however after secondary
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interventions the false lumen volume was reduced in 85% of these patients, how do you explain this? Dr Nathan. The preoperative volume of the true and false lumen in the descending thoracic and abdominal aorta was measured. The postoperative volume of the descending thoracic and abdominal aorta was not measured. Postoperative thrombosis of the DRAD DTA was determined through examination of patients’ last postoperative CTA, including arterial and delayed imaging. The diameter at the point of maximal DRAD DTA was measured on patients’ preoperative and last postoperative CTA. Including the nine patients who underwent secondary aortic interventions, treatment success, which was defined as thrombosis of the false lumen in the area of DRAD DTA with stability or decrease in the maximum diameter of the DRAD DTA on the last postoperative CTA, was achieved in 85.2% of patients. Dr Donayre. Could you elaborate on your CTD patients, you achieved false lumen thrombosis in three and three had
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secondary interventions, what is the follow-up of these patients with regard to persistent false lumen thrombosis? Should they be treated until FL thrombosis is achieved to avoid late death due to rupture in these very challenging patients? Dr Nathan. Of the seven patients with connective tissue disease treated with stent-graft therapy for DRAD DTA, three underwent SAI, three had treatment success, and one was lost to follow-up. Two of the three patients who underwent SAI for progressive upper abdominal aortic aneurysmal degeneration had upper abdominal aortic diameters $4 cm at the time of stent-graft therapy. The three patients with treatment success had DRAD limited to the proximal descending thoracic aorta. The goal of therapy in all patients is thrombosis of the DRAD DTA. Patient with connective tissue disease can be particularly susceptible to continued aneurysmal degeneration of the false lumen and require close clinical follow-up.