Dynamic Indicators That Impact the Outcomes of Thoracic Endovascular Aortic Repair in Complicated Type B Aortic Dissection

CLINICAL STUDY

Dynamic Indicators That Impact the Outcomes of Thoracic Endovascular Aortic Repair in Complicated Type B Aortic Dissection Shuo Zhao, MD, Hui Gu, MD, Baojin Chen, MD, Shifeng Yang, MD, Zhaoping Cheng, MD, Yanhua Duan, MD, Yang Lin, MD, and Ximing Wang, MD ABSTRACT Purpose: To investigate dynamic variables obtained from retrospective computed tomography angiography for ability to predict thoracic endovascular aortic repair (TEVAR) outcomes in patients with complicated type B aortic dissection (cTBAD). Materials and Methods: Seventy-nine patients with cTBAD who received TEVAR from March 2009 to June 2018 were retrospectively enrolled. Relative true lumen area (r-TLA) was computed at the level of tracheal bifurcation every 5% of all R-R intervals. Parameters that reflect the state of intimal motion were evaluated, including difference between maximum and minimum r-TLA (D-TLA) and true lumen collapse. The endpoints comprised early (
30 days) and late (> 30 days) outcomes after intervention. Results: Overall early mortality rate was 13.9% (11/79), and early adverse events rate was 24.1% (19/79). Patients who received TEVAR within 2 days of symptom onset demonstrated the worst outcomes. A longer time of r-TLA < 25% in 1 cardiac cycle (P ¼ .049) and larger D-TLA (P < .001) were correlated to an increased early death. In addition, D-TLA was an independent predictor of early mortality. Area under the curve of D-TLA was 0.849 (95% confidence interval 0.730–0.967) for predicting early mortality and 0.742 (95% CI 0.611–0.873) for predicting early adverse events. Survival and event-free survival rates during follow-up were decreased in the D-TLA > 21.5% group compared with the D-TLA
21.5% group (all P < .001). Conclusions: Larger D-TLA is correlated with worse postoperative outcomes and might be a crucial parameter for future risk stratification in patients with cTBAD.

ABBREVIATIONS AEs ¼ adverse events, CI ¼ confidence interval, cTBAD ¼ complicated type B aortic dissection, D-TLA ¼ difference between maximum and minimum relative true luminal area, ECG ¼ electrocardiogram, LSA ¼ left subclavian artery, r-TLA ¼ relative true luminal area, TEVAR ¼ thoracic endovascular aortic repair, TLC ¼ true lumen collapse, TLC25% ¼ time of relative true lumen area < 25% in a cardiac cycle

Complicated type B aortic dissection (cTBAD) is a catastrophic disease with high morbidity and mortality rates, particularly in the acute phase (1). Current recommended management for cTBAD is thoracic endovascular aortic repair (TEVAR), which can seal the entry tear to promote false lumen

thrombosis and aortic remodeling (2). Although TEVAR for aortic dissection results in a better survival rate during longterm follow-up than the optimal medical treatment (3), patients undergoing TEVAR can be affected by procedural complications, such as stroke and paraplegia, during the acute

From the Department of Radiology (S.Z., H.G., B.C., S.Y., X.W.), Shandong Provincial Hospital, Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-Cerebral Vascular Disease, Shandong University, #324, Jingwu Road, Jinan, Shandong 250021, China; Department of Radiology (Z.C., Y.D.), Shandong Medical Imaging Research Institute, Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-Cerebral Vascular Disease, Shandong University, Jinan, Shandong 250021, China; and Siemens Healthcare Diagnostics Shanghai Co Ltd (Y.L.), Shanghai, China. Received August 13, 2019; final revision received November 4, 2019; accepted November 9, 2019. Address correspondence to X.W.; E-mail: [email protected]

None of the authors have identified a conflict of interest. Figure E1 can be found by accessing the online version of this article on www. jvir.org and clicking on the Supplemental Material tab. © SIR, 2019 J Vasc Interv Radiol 2019; ▪:1–9 https://doi.org/10.1016/j.jvir.2019.11.010

2 ▪ TEVAR Outcomes in Complicated Type B Aortic Dissection

EDITORS’ RESEARCH HIGHLIGHTS  This study assessed dynamic changes in true lumen area during the cardiac cycle as a predictor of early adverse events and survival after thoracic endovascular aortic repair for treatment of complicated type B aortic dissection.  Retrospective electrocardiogram-gated computed tomography angiography images were analyzed at 5% intervals during the cardiac cycle, and true lumen area change was calculated at the level of the carina.  Patients with early mortality and adverse events had significantly larger dynamic change in true lumen, longer duration of true lumen collapse, or maximum false lumen diameter > 22 mm.  Dynamic change of true lumen area during the cardiac cycle of > 21.5% correlated with worse outcomes after thoracic endovascular aortic repair.

phase (4). A previous trial showed that patients undergoing TEVAR for acute cTBAD (0–14 days) had a higher 30-day mortality rate than patients performing the intervention for subacute and chronic dissection (5). Furthermore, the VIRTUE Registry indicated that the optimal TEVAR treatment window for uncomplicated type B dissection is the subacute phase (14– 90 days), which results in better prognoses and similar aortic remodeling to the acute phase (6). However, for patients with acute cTBAD presenting with potentially fatal complications, waiting for days until the subacute phase to stabilize the aorta seems undesirable. Consequently, the identification of potentially high-risk morphologic characteristics is essential to optimize management and improve prognosis of patients with life-threatening complications. Several morphologic parameters have been analyzed in previous studies to identify adverse events (AEs) after the intervention, such as maximum aortic diameter, false lumen diameter, and primary entry tear diameter (7–10); however, the variables were obtained from static images and might not reflect the actual dimensions of the intimal flap and aortic wall, as they fluctuate throughout the cardiac cycle. Retrospective electrocardiogram (ECG)-gated computed tomography (CT) angiography can obtain multiphase images by reconstructing datasets over a heart cycle, allowing clinicians to evaluate the morphologic variables from a dynamic perspective. At the present time, few studies have evaluated the capability of dynamic intimal motion to predict TEVAR outcomes (11,12). This study primarily aimed to estimate the early and late outcomes of TEVAR in patients with cTBAD, particularly investigating the predictive values of dynamic morphologic parameters for TEVAR outcomes using retrospective CT angiography.

MATERIALS AND METHODS Patient Demographics The institutional review board approved this study, and a waiver of informed consent was approved given the

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retrospective nature of the study. Between March 2009 and June 2018, all patients who underwent TEVAR for cTBAD were retrospectively enrolled. Exclusion criteria included the following: (a) chronic dissection (> 90 days); (b) aortic dissection secondary to trauma, iatrogenic injury, or intramural hematoma; (c) unavailability of complete data for retrieval from the hospital medical records system; (d) incomplete follow-up. The analysis included 79 patients (mean age 49.9 years ± 11.9; 77.2% male) who received TEVAR for complicated hyperacute (< 2 days; n ¼ 31), acute (2–14 days; n ¼ 32), or subacute (15–90 days; n ¼ 16) dissection (Fig 1). Comprehensive data, including demographic data, complications, procedural characteristics, and CT angiography morphometric variables, were reviewed. Extension of the intimal flap into the abdominal aorta could be detected in 70 patients (88.6%). Baseline characteristics are listed in Table 1.

Patient Management First-line blood pressure control was achieved by administering antihypertensive medications to maintain a systolic blood pressure < 120 mm Hg, and analgesia was administered if patients experienced persistent pain. The 79 patients with cTBAD underwent emergency TEVAR at a single institution by consensus of the patients and their families for  1 indications: malperfusion (n ¼ 34), aortic rupture (n ¼ 26), early aortic expansion (n ¼ 12), refractory pain (n ¼ 48), and hypertension (n ¼ 12) (Table 1). Malperfusion referred to hypoperfusion of the viscera, kidney, lower extremity, or spinal cord, and patients who fulfilled the previous criteria reported by White et al (13) were recorded in this investigation. Refractory pain was defined as reappearance of pain after previous relief of pain (14). Refractory hypertension was defined as a need for  4 adequately dosed antihypertensive medications simultaneously to achieve blood pressure
140/80 mm Hg (15). Among patients who underwent hyperacute TEVAR, 71.0% (22 of 31) had malperfusion and/or rupture. Thirty-four patients experienced malperfusion: 58.8% (20 of 34) in the kidney, 20.6% (7 of 34) in the visceral organs, 11.8% (4 of 34) in the lower limbs, and 8.8% (3 of 34) in multiple organs. During the procedure, the stent graft was oversized by 10%–15% of the proximal nondissected aorta and was implanted along the dissected aorta to cover the primary proximal entry tear. The median coverage length of the aorta was 180 mm (interquartile range: 160–200 mm). The origins of the left subclavian artery (LSA) were covered by the stent graft if the primary tear was near the LSA. A left common carotid artery–LSA bypass was performed before or after the procedure depending on radiographic assessment of patients’ vertebrobasilar circulation. LSA coverage was carried out in 19 patients (24.1%), and 8 patients (10.1%) received left common carotid artery–LSA bypass before or after TEVAR (Table 1). Lumbar drainage was selectively used in 3 patients (3.8%) based on requirement for LSA coverage

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Figure 1. Study flowchart.

and history of prior aortic surgery. A clamp trial was implemented 24 hours before removal. Patients with suspected or known aortic dissection routinely received retrospective ECG-gated aortic CT angiography on admission. Repeat ECG-gated CT angiography was not required if non–ECG-gated CT demonstrated a definite aortic dissection, and the patient was excluded from the study. Follow-up CT angiography examinations of patients with cTBAD were regularly performed at 3, 6, and 12 months after TEVAR and annually thereafter.

CT Angiography Acquisition and Reconstruction Examinations were performed with a 192-slice dual-source CT scanner (SOMATOM Definition Flash; Siemens Healthcare GmbH, Erlangen, Germany) with retrospective ECG gating. The following parameters were applied: collimation 2  64  0.6 mm with a z-flying focal spot technique, 0.28-second rotation time, pitch of 0.17–0.45 (adjusted for heart rate), 250 reference mAs with automatic tube current modulation (CARE Dose 4D; Siemens Healthcare GmbH), and tube voltage 80 kV or 100 kV (body mass index
25 kg/m2, 80 kV; body mass index > 25 kg/m2, 100 kV). The ECG-gated tube current modulation technique (adaptive ECG-pulsing) was used: full tube current was centered at one phase (70% R-R interval), and 20% of the peak tube current was at the remaining R-R intervals (16). Iodinated contrast material (100–120 mL; Omnipaque 350;

GE Healthcare, Little Chalfont, United Kingdom) was injected at a rate of 4–4.5 mL/s, followed by 30 mL of saline solution at the same rate. Images were reconstructed at every 5% of 0%–95% R-R intervals with a 1.5-mm slice thickness and a 1.0-mm increment using a medium-soft convolution kernel in filtered back projection (B30f).

Analysis of Morphologic Characteristics Preoperative CT angiography images from all eligible patients were retrospectively reviewed by 2 radiologists with 6 (S.Z.) and 8 years (H.G.) of experience in cardiovascular imaging, respectively, who were blinded to clinical outcomes, and the final results were obtained by consensus. Areas of the true lumen and aorta were acquired automatically at the tracheal bifurcation perpendicular to the centerline along the aorta at each R-R interval over the whole heart cycle with an imaging server (syngo.via; Siemens Healthcare GmbH). The program automatically generated a region of interest over the lumen outline by identifying boundaries of the contrasted vessels, and manual correction was used if necessary (Fig E1a–d [available online on the article’s Supplemental Material page at www.jvir.org]). The relative true lumen area (r-TLA) was calculated as follows: r-TLAn ð%Þ ¼ TLAn =AAn  100%

(1)

where TLA denotes true lumen area, AA denotes total aortic area, and n denotes a specific phase of the R-R interval.

4 ▪ TEVAR Outcomes in Complicated Type B Aortic Dissection

Study Endpoints

Table 1. Baseline Characteristics of All Patients (N ¼ 79) Characteristic

Value

Age, y

49.9 ± 11.9

Sex, male

61 (77.2%)

Body mass index, kg/m2

25.1 ± 2.6

Chest and back pain

54 (68.4%)

Abdominal pain

33 (41.8%)

Hypertension

50 (63.3%)

Diabetes mellitus

13 (16.5%)

Smoking Indications

33 (41.8%)

Malperfusion

34 (43.0%)

Aortic rupture

26 (32.9%)

Refractory hypertension

12 (15.2%)

Refractory pain

48 (60.8%)

Early aortic expansion

12 (15.2%)

Procedural parameters LSA coverage LCCA-LSA bypass Branch vessel stent

19 (24.1%) 8 (10.1%) 4 (5.1%)

Note–Data are presented as mean ± SD or n (%). LCCA ¼ left common carotid artery; LSA ¼ left subclavian artery.

The maximum r-TLA and minimum r-TLA in a cardiac cycle were included in the final analysis. To better evaluate the fluctuation of the intima, the difference between the maximum r-TLA and minimum r-TLA (D-TLA) and the true lumen collapse (TLC) were introduced. The equation of D-TLA was as follows: D-TLA ð%Þ ¼ r-TLAmax  r-TLAmin

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(2)

where r-TLAmax denotes maximum r-TLA and r-TLAmin denotes minimum r-TLA. The TLC was assessed by calculating the times at which the r-TLA was < 25% in a cardiac cycle (TLC25%) and < 50% in a cardiac cycle at the tracheal bifurcation throughout the cardiac cycle (7,8). Furthermore, morphologic features observed in static images that were previously reported to be associated with AEs were analyzed in multiphase images (8–10,17). Shortaxis diameters of the aorta and false lumen were measured manually at the level of the upper thoracic descending aorta that was perpendicular to the centerline along the aortic longitudinal axis by multiplanar reformations at every R-R interval (Fig E1e–g [available online on the article’s Supplemental Material page at www.jvir.org]). The maximum diameters of the aortic and false lumen in a heart cycle were obtained. The maximum diameter of primary entry tear was defined as the maximum diameter of the flap breach measured on axial, sagittal, and coronal images in a cardiac cycle (18). Changes of false lumen area and status between the latest follow-up and initial CT angiography images after TEVAR were documented (19).

The primary endpoints were early mortality and early AEs within 30 days after TEVAR, and the secondary endpoints were late mortality and late AEs associated with dissection from > 30 days postoperatively to the study end date. AEs primarily included new neurologic symptoms (stroke, spinal cord ischemia), rupture, organ failure, myocardial infarction, aortic enlargement (> 50 mm), endoleak, and retrograde type A aortic dissection. Outcomes were identified by reviewing the hospital medical records system and by telephone follow-up.

Statistical Analysis Continuous variables are presented as mean ± SD or median (interquartile range), and categorical variables are presented as frequencies and percentages. KolmogorovSmirnov test was performed to test the normal distribution. Continuous variables were evaluated using Student t test or nonparametric Mann-Whitney U test, whereas categorical variables were analyzed using c2 test or Fisher exact test. The correlations between D-TLA, malperfusion and/or rupture, and hyperacute intervention were analyzed by Spearman rank correlation. Cox proportional hazards model was performed to identify independent predictors of early outcomes. A receiver operating characteristic curve analysis was performed to assess the diagnostic roles of D-TLA and determine its best cutoff value. Cumulative survival and event-free rates were estimated by Kaplan-Meier curves and compared by the log-rank test. A P value < .05 indicated statistical significance. All statistical analyses were performed using IBM SPSS Version 20.0 (IBM Corp, Armonk, New York) and GraphPad Prism 6.01 (GraphPad Software, San Diego, California).

RESULTS Early and Late TEVAR Outcomes The median follow-up time was 339 days (interquartile range: 41–566 days). Of 79 enrolled patients, 11 patients died within 30 days after TEVAR, yielding an overall early mortality rate of 13.9% (11 of 79) (Table 2). The 1- and 2-year survival rates of the total cohort were 82.3% and 79.7%, respectively. Among the 11 early deaths, 10 patients (90.9%) underwent TEVAR within first 2 days after symptom onset. Patients who received TEVAR within 2 days (hyperacute) had significantly worse outcomes than patients who received TEVAR in acute or subacute phases (all P < .001) (Fig 2a, b). The overall early AEs rate was 24.1% (19 of 79) (Table 2). Six patients developed new neurologic symptoms after the intervention. One patient experienced a permanent stroke owing to left vertebral artery coverage after placing the stent graft; the patient died within 30 days after the intervention despite an

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Table 2. Early Outcomes after TEVAR in All Patients (N ¼ 79) Parameter

Value

Hospital stay, d

21.3 ± 7.9

Early mortality

11 (13.9%)

Early AEs

19 (24.1%)

New neurologic symptoms

6 (7.6%)

Stroke

4 (5.1%)

Spinal cord ischemia

2 (2.5%)

Rupture

5 (6.3%)

Organ failure Myocardial infarction

4 (5.1%) 2 (2.5%)

Aortic enlargement, > 50 mm

1 (1.3%)

Endoleak

0 (0%)

Retrograde type A aortic dissection

1 (1.3%)

Note–Data are presented as mean ± SD or n (%). AEs ¼ adverse events; TEVAR ¼ thoracic endovascular aortic repair.

immediate left common carotid artery–LSA bypass. Three patients experienced transient stroke and recovered after effective management before discharge. Two patients had transient spinal cord ischemia after the procedure. In addition, 4 patients with rupture, 4 patients with organ failure, and 2 patients with acute myocardial infarction died within 30 days postoperatively. Furthermore, 6 patients underwent reinvention after the initial TEVAR procedure owing to the following complications: 2 developed retrograde type A aortic dissection or aortic enlargement discovered on days 5 and 25 postoperatively, respectively, and the remaining 4 patients experienced aortic enlargement (3 patients) or type Ia endoleak (1 patient) after discharge (> 30 days).

multivariate analyses, only D-TLA was considered as an independent predictor of early mortality (hazard ratio ¼ 1.153, 95% confidence interval [CI] 1.080–1.232, P < .001). With regard to early AEs, multivariate analysis demonstrated that both larger D-TLA (hazard ratio ¼ 1.128, 95% CI 1.059–1.201, P < .001) and maximum diameter of false lumen > 22 mm (hazard ratio ¼ 3.226, 95% CI 1.179– 8.831, P ¼ .023) were independently correlated with increased incidences of early AEs.

Diagnostic Performance of D-TLA for Predicting Early TEVAR Outcomes The predictive value of D-TLA in early outcomes was evaluated by receiver operating characteristic curve analysis. D-TLA showed moderate diagnostic value for detecting early outcomes with a best cutoff value of 21.5% (early mortality, area under the curve ¼ 0.849, 95% CI 0.730–0.967; early AEs, area under the curve ¼ 0.742, 95% CI 0.611–0.873) (Fig 3a, b). Nine patients (29.0%) with hyperacute cTBAD, 6 patients (18.8%) with subacute cTBAD, and 2 patients (12.5%) with acute cTBAD had D-TLA > 21.5%. There was no significant difference between the 3 subgroups in terms of D-TLA > 21.5% (P ¼ .377). Kaplan-Meier curves of early outcomes on the basis of D-TLA were analyzed. The D-TLA > 21.5% group exhibited a worse survival rate in follow-up than the D-TLA
21.5% group (47.1% vs 88.7%, P < .001) (Fig 3c). Additionally, event-free survival rate of patients with D-TLA > 21.5% was lower than in patients with D-TLA
21.5% (29.4% vs 72.6%, P < .001) (Fig 3d). Figures 4 and 5 depict a patient who died within 30 days and an event-free survivor, respectively.

Aortic Remodeling Postoperatively Correlation between Morphologic Characteristics and Early TEVAR Outcomes As demonstrated in Table 3, patients with early mortality had significantly larger D-TLA (24.4% ± 8.3 vs 14.5% ± 6.3, P < .001) and longer TLC25% (P ¼ .049) than patients who survived 30 days. Similarly, a larger D-TLA (20.7% ± 8.4 vs 14.4% ± 6.4, P ¼ .001) and a maximum false lumen diameter > 22 mm (P ¼ .030) occurred more frequently in patients with early AEs than those without early AEs. No significant difference was observed in terms of the other parameters. Spearman’s correlation coefficients between D-TLA and TEVAR indications were r ¼ .420 (P < .001) for aortic rupture and r ¼ .229 (P ¼ .042) for malperfusion. TLC25% showed moderate correlation to malperfusion (r ¼ .406, P < .001). No significant correlations were discovered between D-TLA, TLC25%, and hyperacute intervention (both P > .05). Cox proportional hazards model was performed to determine clinical and morphologic characteristics associated with early outcomes. According to univariate and

Follow-up CT angiography images of the 63 patients who survived were reviewed. A decrease in false lumen area was observed in 51 patients (81.0%) at the tracheal bifurcation level. Thoracic false lumens developed partial thrombosis in 19 patients (30.2%) and complete thrombosis in 40 patients (63.5%) during follow-up, whereas abdominal false lumens exhibited partial thrombosis in 45 patients (71.4%) and complete thrombosis in 9 patients (14.3%). However, no significant differences between the D-TLA > 21.5% and D-TLA
21.5% groups were observed in terms of the decrease of false lumens (P ¼ .826), thoracic false lumen status (P ¼ .447), and abdominal false lumen status (P ¼ .721) after TEVAR.

DISCUSSION This study demonstrated that D-TLA determined by retrospective CT angiography was correlated with postoperative mortality and AEs. With the best cutoff value of 21.5%, D-TLA performed well in predicting early TEVAR outcomes and might be a crucial morphologic characteristic

6 ▪ TEVAR Outcomes in Complicated Type B Aortic Dissection

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Figure 2. Freedom from mortality (a) and AEs (b). Significant differences were found in the survival and event-free survival rates among the 3 phases. The number of patients at risk is listed below the curves.

Table 3. Correlation between Morphologic Characteristics and Early TEVAR Outcomes Early Mortality Late Mortality (n ¼ 11) (n ¼ 68)

P Value

Early AEs (n ¼ 19)

Late AEs (n ¼ 60)

P Value .657

r-TLAmin, %

21.1 ± 8.2

27.8 ± 14.1

.131

25.6 ± 10.0

27.2 ± 14.6

r-TLAmax, %

45.5 ± 8.3

42.3 ± 13.9

.467

46.3 ± 7.5

41.6 ± 14.5

.073

D-TLA, %

24.4 ± 8.3

14.5 ± 6.3

< .001†

20.7 ± 8.4

14.4 ± 6.4

.001*

50 (15–80) 100 (100–100)

0 (0–65) 100 (100–100)

.049* .603

TLC25%, %R-R interval TLC50%,%R-R interval

15 (0–55) 0 (0–80) 100 (100–100) 100 (100–100)

.594 .399

Maximum diameter of descending aorta > 40 mm

4 (36.4%)

27 (39.7%)

.232

8 (42.1%)

23 (38.3%)

Maximum diameter of false lumen > 22 mm

8 (72.7%)

29 (42.6%)

.126

13 (68.4%)

24 (40.0%)

.030*

Maximum diameter of primary entry tear > 10 mm

7 (63.6%)

37 (54.4%)

0.807

10 (52.6%)

34 (56.7%)

.758

Patent

7 (63.6%)

33 (48.5%)

12 (63.2%)

28 (46.7%)

Partial thrombosis

False lumen status

.592

.769

.379

4 (36.4%)

33 (48.5%)

7 (36.8%)

30 (50.0%)

Complete thrombosis Branch vessel involvement

0 (0%) 5 (45.5%)

2 (2.9%) 38 (55.9%)

.519

0 (0%) 11 (57.9%)

2 (3.3%) 32 (53.3%)

.728

False lumen at inner aortic curvature

3 (27.3%)

17 (25.0%)

.872

7 (36.8%)

13 (21.7%)

.185

Note–Data are presented as the mean ± SD, n (%), or median (interquartile range). AEs ¼ adverse events; D-TLA ¼ difference between r-TLAmax and r-TLAmin; r-TLAmax ¼ maximum relative true lumen area; r-TLAmin ¼ minimum relative true lumen area; TEVAR ¼ thoracic endovascular aortic repair; TLC25% ¼ time of relative true lumen area < 25% in a cardiac cycle; TLC50% ¼ time of relative true lumen area < 50% in a cardiac cycle. *P < .05. † P < .001.

for future risk stratification in patients with cTBAD before TEVAR. In the present study, most patients with cTBAD in the hyperacute phase had malperfusion and/or rupture, which are considered life threatening and require urgent intervention (17). However, TEVAR performed in the hyperacute period exhibited the highest mortality and AEs. Consequently, a comprehensive therapeutic strategy might be desirable to balance the urgency of treating fatal complications and minimizing AEs associated with emergency intervention in the hyperacute phase. Interestingly, only 3 patients developed multiorgan malperfusion before intervention in this study, which was less than the number of patients reported in other countries (7,13). This potential

geographic difference needs further elucidation by larger multicenter investigations. The motions of the intimal flap and aortic wall vary as the heart fluctuates (20). Consequently, morphologic characteristics obtained from multiphase CT angiography images were evaluated in this study, and true status of the intima and aortic wall was expected to be reflected more precisely than in static images. In addition to parameters that have been reported in previous studies (9,10), several new parameters were introduced, including D-TLA and TLC, to assess the state of intimal movement. Patients who experienced early mortality had a significantly larger D-TLA and longer TLC25% than survivors. Larger D-TLA and longer TLC25% might represent the instability or collapse of the

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Figure 3. Predictive role of D-TLA for early outcomes. Receiver operating characteristic curves for D-TLA in predicting early mortality (a) and early AEs (b). Kaplan-Meier curves of early mortality (c) and early AEs (d) according to D-TLA. AUC ¼ area under the curve.

Figure 4. Example of an early death. The patient was a 50-year-old man who eventually died owing to acute multiple organ failure on day 2 after intervention for cTBAD. Multiphase CT angiography images demonstrated a large intimal flap oscillation during a cardiac cycle. Maximum r-TLA (r-TLAmax) and minimum r-TLA (r-TLAmin) were obtained at 30% and 80% R-R intervals, respectively (D-TLA ¼ 43.2%) (white arrow). The duration of r-TLA < 25% was 50% of R-R intervals of the whole cardiac cycle, including 0%, 10%, 60%, 70%, 80%, and 90% R-R intervals (black arrow) as well as 5%, 65%, 75%, and 85% R-R intervals (data not shown).

intima, potentially leading to life-threatening rupture and malperfusion, which required urgent intervention (21). However, emergency stent placement might injure the unstable intima and cause death. Therefore, the state of intimal motion, urgent intervention, and death after intervention might be interrelated. Furthermore, D-TLA was an independent risk factor for predicting early mortality, which

indicated that strict surveillance and intensive medical therapy before intervention might need to be considered in subjects with a large D-TLA; moreover, the amplitude of the intimal movement would be helpful to select the size of the stent graft (20). Nevertheless, whether active management based on D-TLA could improve prognosis still requires further larger investigations.

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Figure 5. Example of an event-free survivor during follow-up. Multiphase CT angiography images of a 42-year-old man with no AEs during follow-up revealed a relatively small intimal movement over the heart cycle. The maximum r-TLA (r-TLAmax) and minimum r-TLA (r-TLAmin) were obtained at 20% and 50% R-R intervals, respectively (D-TLA ¼ 18.9%) (white arrow). None of the 0%–95% R-R intervals demonstrated an r-TLA < 25%.

A larger D-TLA might arise from an elevated pressure gradient between false and true lumens, owing to increased blood flow ejecting from the left ventricle directly in endsystole. The enhancement of blood flow was perhaps caused by higher blood pressure (22). Nevertheless, the data of blood pressure during CT angiography examinations was not available owing to the retrospective design of this research. Further prospective studies could consider multivariable analysis incorporating blood pressure and CT angiography characteristics to better estimate TEVAR outcomes and guide individual decision making regarding stent-grafts. D-TLA and TLC25% demonstrated significant correlations with preoperative malperfusion, which indicated that large values of these 2 parameters might reflect transient or sustained collapse of the intima and indirectly affect distal blood flow, especially vessels derived from the true lumen. These alterations could result in malperfusion of corresponding organs supplied (20). Moreover, large D-TLA was significantly correlated with rupture and might also represent an unstable intima. Further studies could focus on verifying the biomechanical validity of intimal fluctuation in predicting worse outcomes by large-scale prospective investigations and application of multiple techniques, including CT angiography, four-dimensional flow magnetic resonance, and computational fluid dynamics models. The maximum false lumen diameter > 22 mm was more likely to be encountered in early AEs. A large false lumen might accelerate aorta dilation and TLC, further causing malperfusion or rupture (15). Moreover, a large entry tear, partial thrombosis, branch vessel involvement, and location of the false lumen were reported to be associated with AEs in other studies (3–25), whereas no significant correlation was discovered in this study. The reasons for these discrepancies might arise from specific study design and sample selection criteria. This study has several limitations. First, the cohort was relatively small, and the results need to be validated with a

larger, multicenter investigation in the future; besides, values of dynamic parameters in management of patients require further elucidation. Moreover, only patients who underwent TEVAR for acute or subacute cTBAD were included; thus, further studies should focus on chronic cTBAD and uncomplicated dissection and evaluate the prognosis of type B dissection more comprehensively. Additionally, some investigations will be carried out in the near future by prospectively collecting data of patients with uncomplicated and complicated type B dissection who received TEVAR to better estimate roles of dynamic characteristics in predicting interventional outcomes. Finally, comprehensive evaluations of daily management of patients with dissection combining clinical setting with imaging analysis are still required. In conclusion, D-TLA obtained from retrospective CT angiography might be a major indicator correlated with unfavorable postoperative outcomes and is useful for future risk stratification in patients with cTBAD before TEVAR.

ACKNOWLEDGMENTS This study was supported by the National Natural Science Foundation of China (Grants 81371548 and 81571672) and Taishan Scholar Program.

REFERENCES 1. Patterson BO, Cobb RJ, Karthikesalingam A, et al. A systematic review of aortic remodeling after endovascular repair of type B aortic dissection: methods and outcomes. Ann Thorac Surg 2014; 97:588–595. 2. Fanelli F, Cannavale A, O’Sullivan GJ, et al. Endovascular repair of acute and chronic aortic type B dissections: main factors affecting aortic remodeling and clinical outcome. JACC Cardiovasc Interv 2016; 9:183–191. 3. Nienaber CA, Kische S, Rousseau H, et al. Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial. Circ Cardiovasc Interv 2013; 6: 407–416. 4. Yang CP, Hsu CP, Chen WY, et al. Aortic remodeling after endovascular repair with stainless steel-based stent graft in acute and chronic type B aortic dissection. J Vasc Surg 2012; 55:1600–1610.

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5. Virtue Registry Investigators. The VIRTUE Registry of type B thoracic dissections—study design and early results. Eur J Vasc Endovasc Surg 2011; 41:159–166. 6. Virtue Registry Investigators. Mid-term outcomes and aortic remodeling after thoracic endovascular repair for acute, subacute, and chronic aortic dissection: the VIRTUE Registry. Eur J Vasc Endovasc Surg 2014; 48: 363–371. 7. Smedberg C, Hultgren R, Delle M, Blohme L, Olsson C, Steuer J. Temporal and morphological patterns predict outcome of endovascular repair in acute complicated type B aortic dissection. Eur J Vasc Endovasc Surg 2018; 56:349–355. 8. Evangelista A, Salas A, Ribera A, et al. Long-term outcome of aortic dissection with patent false lumen: predictive role of entry tear size and location. Circulation 2012; 125:3133–3141. 9. Ante M, Mylonas S, Skrypnik D, et al. Prevalence of the computed tomographic morphological DISSECT predictors in uncomplicated Stanford Type B aortic dissection. Eur J Vasc Endovasc Surg 2018; 56: 525–533. 10. Tolenaar JL, van Keulen JW, Jonker FH, et al. Morphologic predictors of aortic dilatation in type B aortic dissection. J Vasc Surg 2013; 58: 1220–1225. 11. Lortz J, Papathanasiou M, Rammos C, et al. High intimal flap mobility assessed by intravascular ultrasound is associated with better short-term results after TEVAR in chronic aortic dissection. Sci Rep 2019; 9:7267. 12. Lortz J, Tsagakis K, Rammos C, et al. Intravascular ultrasound assisted sizing in thoracic endovascular aortic repair improves aortic remodeling in type B aortic dissection. PLoS One 2018; 13:e0196180. 13. White RA, Miller DC, Criado FJ, et al. Report on the results of thoracic endovascular aortic repair for acute, complicated, type B aortic dissection at 30 days and 1 year from a multidisciplinary subcommittee of the Society for Vascular Surgery Outcomes Committee. J Vasc Surg 2011; 53: 1082–1090. 14. Januzzi JL, Movsowitz HD, Choi J, Abernethy WB, Isselbacher EM. Significance of recurrent pain in acute type B aortic dissection. Am J Cardiol 2001; 87:930–933.

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15. Januzzi JL, Sabatine MS, Choi JC, Abernethy WB, Isselbacher EM. Refractory systemic hypertension following type B aortic dissection. Am J Cardiol 2001; 88:686–688. 16. Yang S, Li X, Chao B, et al. Abdominal aortic intimal flap motion characterization in acute aortic dissection: assessed with retrospective ECGgated thoracoabdominal aorta dual-source CT angiography. PLoS One 2014; 9:e87664. ~a JP, Lai DT, Mitchell RS, et al. Is medical therapy still the optimal 17. Uman treatment strategy for patients with acute type B aortic dissections? J Thorac Cardiovasc Surg 2002; 124:896–910. 18. Quint LE, Platt JF, Sonnad SS, Williams DM. Aortic intimal tears: detection with spiral computed tomography. J Endovasc Ther 2003; 10:505–510. 19. Lombardi JV, Cambria RP, Nienaber CA, et al. Aortic remodeling after endovascular treatment of complicated type B aortic dissection with the use of a composite device design. J Vasc Surg 2014; 59:1544–1554. 20. Ganten MK, Weber TF, von Tengg-Kobligk H, et al. Motion characterization of aortic wall and intimal flap by ECG-gated CT in patients with chronic B-dissection. Eur J Radiol 2009; 72:146–153. 21. Reutersberg B, Trenner M, Haller B, et al. The incidence of delayed complications in acute type B aortic dissections is underestimated. J Vasc Surg 2018; 68:356–363. 22. Murayama T, Funabashi N, Uehara M, Takaoka H, Komuro I. New classification of aortic dissection during the cardiac cycle as pulsating type and static type evaluated by electrocardiogram-gated multislice CT. Int J Cardiol 2010; 142:177–186. 23. Trimarchi S, Tolenaar JL, Jonker FH, et al. Importance of false lumen thrombosis in type B aortic dissection prognosis. J Thorac Cardiovasc Surg 2013; 145(3 Suppl):S208–S212. 24. Clough RE, Barilla D, Delsart P, et al. Editor’s choice—long-term survival and risk analysis in 136 consecutive patients with type B aortic dissection presenting to a single centre over an 11 year period. Eur J Vasc Endovasc Surg 2019; 57:633–638. 25. Schwartz SI, Durham C, Clouse WD, et al. Predictors of late aortic intervention in patients with medically treated type B aortic dissection. J Vasc Surg 2018; 67:78–84.

9.e1 ▪ TEVAR Outcomes in Complicated Type B Aortic Dissection

Zhao et al ▪ JVIR

Figure E1. Area and diameter measurement procedure. (a–d) The centerline along the aortic longitudinal axis was drawn by threedimensional reconstruction. Areas of the true lumen and aorta were automatically measured at the level of the tracheal bifurcation perpendicular to the centerline at each R-R interval. (e–g) Short-axis diameters of the aorta and false lumen were measured manually at the level of the upper thoracic descending aorta that was perpendicular to the centerline along the aorta by double-oblique multiplanar reconstructions at each R-R interval.