Prognosis and Remodeling after Endovascular Repair for Acute,Subacute,and Chronic Type B Aortic Dissection

Abstract

Purpose:

Thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD) is already well introduced, but the best time point to perform TEVAR has not been defined. This study was to report mid- to long-term outcomes and aortic remodeling of TEVAR in patients with TBAD.

Materials and Methods:

In total, 318 TBAD patients from June 2001 to May 2016 were retrospectively reviewed. Patients were divided into 3 groups depending on interval between dissection onset to TEVAR: acute (0–7 days), subacute (8–30 days), and chronic (>30 days). Clinical and morphological data were collected and analyzed.

Results:

The follow-up aorta-related mortality rates in the 3 groups were 17.6%, 2.6%, 4.2%, and the proximal stent-induced new entry rates were 11.8%, 1.6%, 2.8%, respectively. Aortic remodeling was satisfied in both the acute and subacute group, but the false lumen diameter did not decrease (p>0.05) in the chronic group. Compared with the VIRTUE classification (acute, 0–14 days; subacute, 15–92 days; chronic, >92 days), mid- to long-term outcomes of patients within the first overlapped interval between the 2 classifications (8–14 days) were similar to that of subacute patients (15–30 days), while aortic remodeling of patients in the second overlapped interval (31–92 days) was similar to that of chronic patients (>92 days).

Conclusions:

This study suggests that TEVAR for subacute TBAD is associated with a low long-term rate of aorta-related death. Aortic remodeling of chronic dissections is not satisfactory. Additional results suggest that the subacute phase (8–30 days) may be the optimal time to perform TEVAR for uncomplicated TBAD.

Keywords

type B aortic dissection endovascular repair time point remodeling Asian

Introduction

For type B aortic dissection (TBAD), successful thoracic endovascular aortic repair (TEVAR) is based on remodeling of the aorta, including reperfusion of the true lumen and shrinkage of the false lumen, and the absence of complication such as post-TEVAR aortic rupture, type I entry flow, and stent-induced new entry (SINE). Multiple studies have examined possible factors that may influence aortic remodeling and complications, including the time point when TEVAR is performed.^1–4

Traditionally, TBAD patients have been divided into an acute and chronic phase according to the interval between dissection onset and TEVAR (<14 days, acute and >14 days, chronic).⁴ However, a study indicated that there may be an interim phase, a subacute phase, between the acute and chronic phase of a TBAD, while TEVAR needed to be performed before 2 weeks in certain patients, such as those with intractable chest pain or rapid enlargement of the false lumen.⁵ Another hypothesis was proposed that the dissecting aortic intima was fragile in acute phase, and TEVAR in the subacute phase would be safer because of stabilization of the intimal flap.⁶

The results of INSTEAD-XL trial also indicated that TEVAR provided an advantage over medical therapy for subacute TBAD.⁷ In another study, a study of 1815 cases showed that mortality and secondary intervention rates were higher in acute and chronic dissections, respectively, than in subacute dissections.⁸ Nevertheless, differences in aortic remodeling when TEVAR is performed at different stages of TBAD have not been fully examined, and there remain various definitions of TBAD stage.

Thus, the purpose of this study was to report mid- to long-term outcomes and morphological changes of patients with acute, subacute, and chronic TBADs who received TEVAR at our institution. We also compared the results between 2 frequently used staging methods, wished to find out the ideal time for TEVAR.

Materials and Methods

Patient Selection

The records of 636 consecutive patients with TBADs who received or not received TEVAR at our center from June 2001 to May 2016 were retrospectively reviewed. After applying inclusion and exclusion criteria, 318 patients were included in this study for further analysis. The inclusion criteria for this analysis were (1) TBAD diagnosed by computed tomographic angiography (CTA), the distance from primary entry tear to left subclavian artery should be at least 1.5cm; (2) received TEVAR for the first time after dissection onset; (3) at least 1 thoracic stent graft was placed. Exclusion criteria were (1) type A aortic dissection, including retrograde type A aortic dissection; dissection involving supra-aortic arch branches, received or not received chimney technique or bypass. (2) TBAD with dissected aorta only restricted to descending aorta or abdominal aorta; (3) penetrating ulcer; (4) TBAD with proximal entry tear at the level of abdominal aorta; (5) received a restrictive bare stent technique, which described in our published article⁹; (6) dissection combined with connective disease, aortitis, or arteritis.

The protocol for this study was approved by the Institutional Review Board. All patients provided written informed consent for all surgical procedures.

Definitions of TBAD Stage

Two definitions of TBAD stage were used in this study. The first was stages described in 2008¹⁰: acute: 0 to 7 days between dissection onset and TEVAR; subacute: 8 to 30 days; and chronic: >30 days (Figure 1). The current definition was that described in the VIRTUE Registry⁶: acute: 0 to 14 days between dissection onset and TEVAR; subacute: 15 to 92 days; and chronic: >92 days (Figure 1). At our center, all TBAD, both complicated and uncomplicated, will be considered for TEVAR. Criteria of a complicated TBAD, following SVS/STS TBAD guideline, are distal malperfusion (including renal, visceral, lower extremity malperfusion, spinal cord ischemia, stroke), impending/existing rupture, and escalation of care (including resistant hypertension, persistent chest or back pain, readmitted for dissection-related reasons). Patients with a TBAD who met one or more of the criteria were considered for emergency endovascular repair.

Endovascular Aortic Repair Procedures

The size of the thoracic stent graft was selected according to the aortic diameter of the proximal landing zone assessed by preoperative CTA, with 10% oversizing. Basing on 10%, the oversizing will be decreased for patient with high risk of proximal SINE (eg, acute patient), or expanded for patient with high risk of entry flow (eg, atherosclerosis of proximal landing zone, with severe calcified lesion), by surgeon’s evaluation (actual oversizing was adjusted according to the size interval of the specific type of thoracic stent graft). After aortography, the thoracic stent graft was introduced into the proximal landing zone and deployed to seal the proximal entry tear.

Follow-up Protocol

All patients received CTA at 7 days after surgery, then at 3, 6, and 12 months, and then yearly thereafter. Overall aortic size, blood flow, the diameter of the 2 lumens, the occurrence of complications, and characteristics of the thoracic stent graft were evaluated.

Data Collection and Definitions

CTA images taken before and after the primary TEVAR were collected. The entire thoracic aorta was evaluated at 4 different levels, as described by Gorlitzer et al,¹¹ and as described in our prior study.⁹ The diameters of the true and false lumens were measured at the 4 levels: level A: directly distal to the origin of the left subclavian artery; level B: the level of pulmonary artery; level C: at the distal edge of the thoracic stent graft; level D: the level of the diaphragm. Changes in true and total lumen diameters, expressed as a ratio (change ratio) to the preoperative baseline lumen diameter, were evaluated for significant changes over time.

Statistical Analysis

Continuous variables were presented as mean ± standard deviation, and compared by a 2-sided t test or Wilcoxon rank sum test. Categorical variables were compared by a 2-sided chi-square test or Fisher exact test. Comparisons of changes of the lumen change ratio were performed by analysis of variance. Survival analysis was performed using the Kaplan-Meier method. SPSS version 17.0 statistical software (SPSS Inc., Chicago, IL) and GraphPad Prism version 5.0 (GraphPad Software Inc., La Jolla, CA) were used for statistical analysis and the creation of charts, respectively. Values of p<0.05 were considered statistically significant.

Results

Patient Characteristics and Risk Factors

Patient characteristics and risk factors are summarized in Table 1. At first, patients were grouped by TBAD staging method proposed by our center (acute: 0–7 days; subacute: 8–30 days; and chronic: >30 days). The mean age of patients in the acute group (n=40) was 55.5±13.8 years, in the subacute group (n=201) was 52.9±11.8 years, and in the chronic group (n=77) was 55.0±12.3 years. The overall complicated TBAD of different groups is 10 (25%), 50 (24.9%), and 11 (14.3%), respectively (p=0.150). The baseline data were comparable among the 3 groups. The thoracic stent grafts used were Valiant and Talent (Medtronic, Santa Rosa, CA), Zenith TX2 (Cook Medical, Bloomington, IN), TAG (W. L. Gore & Associates, Flagstaff, AZ), Ankura (LifeTech Medical, Shenzhen, China), and Hercules-T (MicroPort Medical, Shanghai, China). Details of the thoracic stent grafts are presented in Table 2. There were no differences in the numbers of the types of stent grafts used among the 3 groups (Table 2 and Supplemental Table 1, p>0.05).

Table 1.

Patient Characteristics, Risk Factors of TBAD Patients.

	^†Acute. No. or mean (SD) (n=40)	Range or %	^†Subacute. No. or mean (SD) (n=201)	Range or %	^†Chronic. No. or mean (SD) (n=77)	Range or %	p
Age, years	55.5±13.8	25–77	52.9±11.8	28–81	55.0±12.3	30–85
Male	34	85.0	167	83.1	71	92.2	0.153
Characteristics
Hypertension	37	92.5	159	79.1	72	93.5	0.004
Diabetes mellitus	0	0.0	7	3.5	7	9.1	0.066
Coronary artery disease	3	7.5	7	3.5	3	3.9	0.492
Renal impairment	3	7.5	16	8.0	10	13.0	0.456
Previous stroke	0	0.0	4	2.0	5	6.5	0.098
Complicated TBAD	10	25.0	50	24.9	11	14.3	0.150
Malperfusion	6	15.0	44	21.9	9	11.7	0.121
Impending rupture	2	5.0	7	3.5	3	3.9	0.898
Resistant hypertension	2	5.0	4	2.0	2	2.6	0.597
Persistent chest or back pain	4	10.0	13	6.5	3	3.9	0.434

Abbreviations: TBAD, type B aortic dissection. SD, standard deviation.

†

Definitions of TBAD stage (acute, subacute, and chronic) were those raised by our center first in 2008 (acute: 0–7 days; subacute: 8–30 days; and chronic: >30 days).

Table 2.

Data of Thoracic Stent Graft.

	^†Acute. No. or mean (SD) (n=40)	Range or %	^†Subacute. No. or mean (SD) (n=201)	Range or %	^†Chronic. No. or mean (SD) (n=77)	Range or %	p
Proximal landing zone diameter, mm	29.6±2.6	27.7–35.0	29.7±2.8	23.4–36.3	30.8±2.2	24.4–34.7	0.188
Thoracic stent graft
Valiant (Medtronic)	13	32.5	92	45.8	32	41.6	0.288
Talent (Medtronic)	14	35.0	57	28.4	27	35.1	0.461
TAG (Gore)	3	7.5	21	10.4	10	13.0	0.688
Zenith TX2 (COOK)	6	15.0	17	8.5	5	6.5	0.293
Ankura (LifeTech)	4	10.0	10	5.0	3	3.9	0.395
Aegis (MicroPort)	0	0.0	4	2.0	0	0.0	0.754
Diameter, mm	31.9±2.6	30–37	32.4±3.0	26–40	33.7±2.5	28–38	0.061
Length, mm	181.0±20.1	150–200	178.8±24.8	120–260	185.5±25.4	150–250	0.450

Abbreviation: SD, standard deviation.

†

Definitions of TBAD stage (acute, subacute, and chronic) were those raised by our center first in 2008 (acute: 0–7 days; subacute: 8–30 days; and chronic: >30 days).

Comparison of Outcomes for Acute, Subacute, and Chronic Group

Preoperative CTA data revealed no significant differences among the 3 groups (Table 2). The aortic-related mortality rate of the acute group (4/40, 10%; 1 proximal SINE; 1 distal SINE; 2 distal dissection ruptures) was significantly higher than that of the subacute group (3/201, 1.5%; 1 proximal SINE and 2 distal dissection ruptures) and of the chronic group (1/77, 1.3%; 1 proximal SINE) (p=0.016) (Table 3). The postoperative spinal cord ischemia rate of the acute group (1/40, 2.5%) was higher than that of the subacute group (1/201, 0.5%) and that of the chronic group (0/77, 0%), but the difference was not significant (p=0.294). The aortic coverage length of these 2 patients were 120 and 200 mm, respectively.

Table 3.

Patient Outcomes of TBAD Patients.

	^†Acute. No. or median (IQR) (n=40)	%	^†Subacute. No. or median (IQR) (n=201)	%	^†Chronic. No. or median (IQR) (n=77)	%	p
30-day mortality	4	10.0	6	3.0	2	2.6	0.117
Aorta-related mortality	4	10.0	3	1.5	1	1.3	0.016
Type I entry flow	4	10.0	20	10.0	9	11.7	0.927
Type II entry flow	0	0.0	4	2.0	5	6.5	0.098
Proximal SINE	1	2.5	1	0.5	1	1.3	0.306
Distal SINE	1	2.5	0	0.0	0	0.0	0.126
Stroke	3	7.5	5	2.5	1	1.3	0.185
Spinal ischemia or paraplegia	1	2.5	1	0.5	0	0.0	0.294
Follow-up. months	19.2 (76.3)		15.9 (40.1)		33.7 (51.4)
Lost	2	5.6	3	1.5	4	5.3	0.171
Mortality	12	35.3	10	5.2	9	12.7	0.000
Aorta-related mortality	6	17.6	5	2.6	3	4.2	0.007
Aorta rupture	3	8.8	3	1.6	2	2.8	0.123
Proximal SINE	4	11.8	3	1.6	2	2.8	0.032
Distal SINE	1	2.9	5	2.6	3	4.2	0.805
Secondary intervention	3	8.8	11	5.7	7	9.9	0.481
Aorta-related secondary intervention	2	5.9	7	3.6	6	8.5	0.308

Abbreviations: IQR, interquartile range; SINE, stent graft-induced new entry; TBAD, type B aortic dissection.

†

Definitions of TBAD stage (acute, subacute, and chronic) were those raised by our center first in 2008 (acute: 0–7 days; subacute: 8–30 days; and chronic: >30 days).

During the follow-up period, the cumulative follow-up mortality rate and the aorta-related mortality rate of the acute group (35.3 and 17.6%, respectively) were significantly higher than that of the subacute group (5.2% and 2.6%, respectively) and that of the chronic group (12.7% and 4.2%, respectively) (p=0.000 and p=0.007, respectively, Table 3). The 144-month cumulative survival and aorta-specific survival of the 3 groups represented by Kaplan-Meier curves are shown in Figure 2. The proximal SINE rate of the acute group (11.8%) was significantly higher than that of the subacute group (1.6%) and the chronic group (2.8%) (p=0.032). The secondary operation rate and the aorta-related secondary operation rate of the chronic group (9.9 and 8.5%, respectively) were higher than that of the acute group (8.8% and 5.9%, respectively) and the subacute group (5.7% and 3.6%, respectively), but the differences were not significant (p=0.481 and 0.308, respectively). For acute, subacute, and chronic patients, the primary reason for a secondary operation was proximal SINE or RTAAD (2/2, 100%), distal SINE (3/7, 42.9%), and enlarged distal dissection (3/6, 50%), respectively. The cumulative free from rupture, proximal SINE, distal SINE, aorta-related secondary intervention presented by Kaplan-Meier curves is shown in Supplemental Figures 1–4. We compared them using log-rank, and the p value was 0.081, 0.089, 0.207, 0.185, respectively. In addition, the non-aortic-related complications are presented in Supplemental Table 2.

Outcomes of Uncomplicated Patients for Acute, Subacute, and Chronic Group

We compared the outcomes of complicated and noncomplicated patients. Between these 2 groups, 30-day mortality of complicated group (8.5%) was significantly higher than noncomplicated group (2.5%, p=0.034), the data are presented in Supplemental Table 3. In addition, we compared the outcomes for the acute, subacute, and chronic group in uncomplicated patients. The results revealed that the follow-up mortality and aorta-related mortality of acute group (39.3% and 21.4%, respectively) were significantly higher than subacute group (4.2% and 2.8%, respectively) and chronic group (13.1% and 4.9%, respectively) (p=0.000 and p=0.005, respectively, Table 4).

Table 4.

Patient Outcomes of Uncomplicated TBAD Patients.

	^†Acute. No. or median (n=30)	%	^†Subacute. No. or median (n=146)	%	^†Chronic. No. or median (n=62)	%	p
30-day mortality	2	6.7	6	2.1	2	1.6	0.400
Aorta-related mortality	2	6.7	3	1.4	1	1.6	0.293
Proximal SINE	1	3.3	1	0.0	1	1.6	0.081
Distal SINE	0	0.0	0	0.0	0	0.0	—
Rupture	1	3.3	5	1.4	1	0.0	0.475
Follow-up
Mortality	11	39.3	10	4.2	9	13.1	0.000
Aorta-related mortality	6	21.4	5	2.8	3	4.9	0.005
Proximal SINE	3	10.7	3	1.4	2	3.3	0.079
Distal SINE	1	3.6	5	2.1	3	4.9	0.570
Rupture	3	10.7	11	2.1	7	1.6	0.111
Aorta-related secondary intervention	2	7.1	7	2.8	6	9.8	0.115

Abbreviations: SINE, stent graft-induced new entry; TBAD, type B aortic dissection.

†

Definitions of TBAD stage (acute, subacute, and chronic) were those raised by our center first in 2008 (acute: 0–7 days; subacute: 8–30 days; and chronic: >30 days).

Aortic Remodeling

Remodeling of the aorta at 4 different levels is plotted in Figure 3. In the acute group and the subacute group, the true lumen diameter was significantly increased, and the false lumen diameter was significantly reduced at levels A, B, and C (p<0.05, Table 5). In the chronic group, the true lumen diameter was significantly increased only at levels A and C, and the false lumen diameter was reduced at levels A, B, and C, but the difference was not significant. Importantly, the total lumen ratio of level D in the chronic group was >1. This indicated that the false lumen at this level progressively enlarged during the follow-up period, though the difference was not significant (p=0.996).

Table 5.

Aortic Remodeling Over Time.

	Before operation	After operation					p
	Before operation	7 days	3 months	6 months	12 months	24 months	p
Level A*
Acute
True lumen, mm	25.2±1.6	27.8±1.9	28.9±1.3	29.7±1.5	29.7±1.5	29.8±1.5	0.000
Total lumen, mm	33.8±2.3	34.7±2.3	32.2±2.9	31.4±2.1	31.0±2.0	30.7±2.0	0.000
Subacute
True lumen, mm	24.8±3.1	28.2±2.4	29.8±2.5	30.4±2.5	30.5±2.7	30.6±2.7	0.000
Total lumen, mm	36.6±4.7	36.5±4.5	33.2±4.5	32.3±4.5	32.3±4.6	32.3±4.7	0.000
Chronic
True lumen, mm	27.3±4.5	29.3±3.4	29.9±3.2	30.1±3.2	30.2±3.3	30.2±3.3	0.012
Total lumen, mm	44.3±8.9	45.1±9.1	44.5±10.0	44.2±10.3	44.0±10.1	43.9±10.3	0.998
Level B*
Acute
True lumen, mm	24.8±2.1	26.8±1.6	27.7±1.7	28.5±2.2	28.5±2.2	28.6±2.2	0.000
Total lumen, mm	32.7±2.9	34.4±3.0	31.5±3.7	30.5±2.8	30.0±2.8	29.8±2.7	0.000
Subacute
True lumen, mm	23.5±3.2	27.0±2.4	28.6±2.5	29.2±2.5	29.4±2.6	29.5±2.6	0.000
Total lumen, mm	34.6±4.0	35.5±4.3	32.4±4.4	31.4±4.6	31.4±4.6	31.5±4.7	0.000
Chronic
True lumen, mm	27.0±4.7	28.4±3.5	28.9±3.3	29.1±3.3	29.3±3.3	29.4±3.3	0.115
Total lumen, mm	42.5±9.3	43.0±8.4	42.9±9.3	43.0±9.5	43.0±9.5	42.8±9.9	1.000
Level C*
Acute
True lumen, mm	23.5±2.3	25.3±2.4	26.7±2.1	27.4±2.2	27.4±2.2	27.4±2.2	0.000
Total lumen, mm	31.4±2.6	32.5±2.9	31.2±2.2	30.7±1.7	30.2±1.8	30.0±1.9	0.047
Subacute
True lumen, mm	22.4±3.3	25.5±2.2	27.1±2.3	27.8±2.2	28.0±2.4	28.1±2.4	0.000
Total lumen, mm	33.0±3.9	34.0±4.0	31.4±4.5	30.5±4.4	30.5±4.6	30.6±4.7	0.000
Chronic
True lumen, mm	25.7±4.1	27.7±3.5	28.2±3.2	28.6±3.2	28.6±3.3	28.7±3.3	0.009
Total lumen, mm	42.4±9.6	42.8±9.6	43.4±10.0	43.7±10.1	43.5±9.9	43.0±10.4	0.997
Level D*
Acute
True lumen, mm	22.0±2.0	23.1±3.3	23.5±3.2	24.2±3.6	24.2±3.7	24.1±3.7	0.437
Total lumen, mm	29.2±1.7	30.1±2.2	29.2±2.7	29.3±2.1	29.3±2.3	29.3±2.6	0.913
Subacute
True lumen, mm	21.2±2.8	22.8±2.7	23.9±2.7	24.2±2.7	24.3±2.7	24.3±2.6	0.000
Total lumen, mm	30.6±3.5	31.3±3.9	30.7±4.7	30.3±4.6	30.3±4.8	30.4±5.3	0.678
Chronic
True lumen, mm	23.9±3.3	24.7±3.2	25.3±3.1	25.6±3.0	25.6±3.0	25.6±3.0	0.279
Total lumen, mm	36.9±6.5	37.2±7.1	37.5±7.4	37.8±7.1	37.7±6.8	37.8±6.9	0.996

Values are reported as mean ± standard deviation.

Level A: directly distal to the origin of the left subclavian artery.

Level B: level of pulmonary artery.

Level C: level of distal edge of the thoracic stent graft.

Level D: level of the diaphragm.

Comparison of the 2 TBAD Staging Methods

Patients grouped according to the current classification, and their clinical data are presented in Table 6. There were no significant differences in the mortality and aorta-related mortality rates, and the proximal SINE rate among the 3 groups.

Table 6.

Overall Clinical Data of TBAD Patients Regrouped via 2 Different Strategies.

	^‡Current staging strategy				^§Draft staging strategy
	Acute. No. or mean (n=104)	Subacute. No. or mean (n=179)	Chronic. No. or mean (n=35)	P	Acute. No. or mean (n=40)	Subacute. No. or mean (n=201)	Chronic. No. or mean (n=77)	P
30-day mortality	6	5	1	0.389	4	6	2	0.117
Aorta-related mortality	5	3	0	0.179	4	3	1	0.016
Type I entry flow	14	16	3	0.471	4	20	9	0.927
Proximal SINE	1	2	0	1.000	1	1	1	0.306
Distal SINE	1	0	0	0.437	1	0	0	0.126
Stroke	5	3	1	0.263	3	5	1	0.185
Spinal ischemia or paraplegia	1	1	0	1.000	1	1	0	0.294
Follow-up
Mortality	14	12	5	0.100	12	10	9	0.000
Aorta-related mortality	7	4	3	0.057	6	5	3	0.004
Aortic rupture	2	2	2	0.195	1	3	2	0.559
Proximal SINE	5	3	1	0.263	4	3	2	0.021
Distal SINE	2	5	2	0.467	1	5	3	0.783

Abbreviations: SINE, stent graft-induced new entry; TBAD, type B aortic dissection.

‡

Definitions of VIRTUE Registry staging strategy, acute: 0–14 days; subacute: 15–92 days; and chronic: >92 days.

Definitions of Draft staging strategy, acute: 0–7 days; subacute: 8–30 days; and chronic: >30 days.

The current classification and our staging classification have 2 overlapped intervals, 8 to 14 days and 31 to 92 days, respectively (Figure 1). To determine whether there was any significance to the overlapped intervals, we regrouped the patients in the study into 5 groups: acute (0–7 days, n=40); interval 1 (8–14 days, n=64); subacute (15–30 days, n=137); interval 2 (31–92 days, n=42); chronic (>92 days, n=35) (Table 7). The follow-up mortality rates and the aorta-related mortality rates were significantly different between the acute group (35.3% and 17.6%, respectively) and the interval 1 group (3.3% and 1.6%, respectively) (p<0.05). The comparison of morphological remodeling is presented in Figure 4 and Supplemental Table 4. Importantly, in the interval 2 group, the true lumen diameter was not significantly increased, and the false lumen diameter was not significantly decreased at all 4 levels. These findings were also noted in the chronic group.

Table 7.

Overall Clinical Data of TBAD Patients via 5 Different Intervals.

	^‡Acute′ (n=40)	%	Interval 18–14 days(n=64)	%	^‡Subacute′(n=137)	%	Interval 231–92 days(n=42)	%	^‡Chronic′ (n=35)	%	p
30-day mortality	4	10.0	2	3.1	4	2.9	1	2.4	1	2.9	0.351
Aorta-related mortality	4	10.0	1	1.6	2	1.5	1	2.4	0	0.0	0.053
Type I entry flow	4	10.0	10	15.6	10	7.3	6	14.3	3	8.6	0.369
Proximal SINE	1	2.5	0	0.0	1	0.7	1	2.4	0	0.0	0.358
Distal SINE	1	2.5	0	0.0	0	0.0	0	0.0	0	0.0	0.236
Stroke	3	7.5	2	3.1	3	2.2	0	0.0	1	2.9	0.312
Spinal ischemia or paraplegia	1	2.5	0	0.0	1	0.7	0	0.0	0	0.0	0.527
Follow-up
Lost	2	5.6	1	1.6	2	1.5	1	2.4	3	8.8	0.281
Mortality	12	35.3	2	3.3	8	6.1	4	10.0	5	16.1	0.000
Aorta-related mortality	6	17.6	1	1.6	4	3.1	0	0.0	3	9.7	0.003
Aorta rupture	1	2.9	1	1.6	2	1.5	0	0.0	2	6.5	0.289
Proximal SINE	4	11.8	1	1.6	2	1.5	1	2.5	1	3.2	0.055
Distal SINE	1	2.9	1	1.6	4	3.1	1	2.5	2	6.5	0.751

Abbreviations: SINE, stent graft-induced new entry; TBAD, type B aortic dissection.

‡

Acute′: 0–7 days; Subacute′: 15–30 days; Chronic′: >92 days.

Discussion

The results of this study showed that mortality and complication rates were different in patients with acute, subacute, and chronic TBADs who were treated with TEVAR. Mortality of the acute group (10%, 15.8%) was significantly higher than that of the subacute group (1.5%, 2.5%) and that of the chronic group (1.3%, p=0.016; 4.1%, p=0.004). The incidence of proximal SINE and subsequent RTAAD in the acute group during follow-up (11.8%) was significantly higher than in the subacute group (1.6%) and the chronic group (2.8%, p=0.032). Dong et al¹² studied 443 TBAD patients treated with TEVAR and reported the incidence of RTAAD was 2.5%. Other studies considered this complication to be related to fragility of the inflammatory and edematous aortic intima and excessive pressure after TEVAR at the level of the proximal edge of the stent graft.^6,13 Our results indicate that the mortality and incidence of proximal SINE and subsequent RTAAD is higher in patients with an acute TBAD treated with TEVAR. To clarify the impact of complicated TBAD on the mortality and morbidity, we compared the outcomes of complicated and noncomplicated patients. The results revealed that 30-day mortality of complicated group was significantly higher than noncomplicated group (p=0.034, Supplemental Table 3), which indicated that the impact of complicated TBAD on mortality and morbidity may be large.

Considering the large impact of complicated TBAD, to better understand the long-term impact of timing TEVAR in TBAD patients, we compared the outcomes for the acute, subacute, and chronic group in uncomplicated patients. The result revealed that the follow-up mortality and aorta-related mortality of acute group were significantly higher than subacute group and chronic group. The incidence of proximal SINE in acute group (10.7%) was higher than subacute (1.4%) and chronic group (3.3%, p=0.079), though not significant. As such, we do not suggest TEVAR should be used to treat an acute TBAD, unless it is a complicated dissection. Thus, we suggested that TEVAR for a noncomplicated acute TBAD should be a deferred TEVAR and should be performed in the subacute stage.

The aorta-related secondary operation rate is an important factor that is related to the prognosis of patients with a TBAD treated with TEVAR. Our results revealed that the primary reason for a secondary operation in acute, subacute, and chronic patients was proximal SINE or RTAAD, distal SINE, and enlarged distal dissection, respectively. This result suggests that the reasons for a secondary operation are related to pathological differences of different TBAD stages, and the technical aspects of TEVAR.

The relevant issues of the acute group have been described above. In the subacute group, the mismatch between the true lumen diameter at the distal stent edge and the true lumen diameter of the nonstented segment, away from the stent edge, will lead to the occurrence of distal SINE. We described this issue in our previous study, and we suggested that a restrictive bare stent be used to prevent the occurrence of distal SINE.⁹

In the chronic group, the primary reason for a secondary operation was an enlarged distal dissection and poor capability for remodeling.^6,14 Previous studies have shown that the aortic remodeling of an acute dissection is significantly faster than that of a chronic dissection.^15,16 Our result suggests that the plasticity of acute and subacute dissections is considerable, while the histopathological structure of chronic dissections is relatively stable, and the capability for remodeling is relatively lower than that of acute and subacute dissections. Thus, to increase the probability of favorable remodeling TEVAR for TBAD should be performed in the acute or subacute stage.

Staging classifications for TBAD are controversial. There are overlaps between current staging and our definitions: 8 to 14 days (interval 1) and 30 to 92 days (interval 2). Our results revealed that the mortality and aorta-related mortality rates of interval 1 (3.3% and 1.6%, respectively) were significantly lower than that of the acute group (35.3% and 17.6%, respectively, p<0.05), but similar to that of the subacute group (6.1% and 3.1%, respectively). The proximal SINE rate of interval 1 was 1.6%, with is lower than that of the acute group (11.8%), but similar to that of the subacute group (1.5%). As we mentioned above, the incidence of proximal SINE and subsequent RTAAD was higher in acute TBAD patients after TEVAR. Taken together, the results suggest that the clinical outcomes characteristics of patients in interval 1 (8–14 days) may be closer to the subacute ones.

For interval 2 patients, the mortality, aorta-related mortality, and complication rates were not different from those of the subacute or chronic group; however, the true lumen diameter did not increase during the follow-up period, nor did the false lumen diameter decrease. We previously mentioned that based on the results of this study, the remodeling capability of chronic dissection is relatively lower than that of acute and subacute dissection. As such, the remodeling characteristics of patients in interval 2 (30–92 days) may be closer to that of patients with a chronic dissection.

Our results revealed that the false lumen diameter did not decrease in the nonstented segment of the dissected aorta (Figures 3 and 4). This may be related to the radial support force of the stent graft, and the increase in diameter of the true lumen. However, extension of stented segment should be considered with caution due to the risk of spinal cord ischemia and distal SINE. Restrictive bare stent grafting may be a solution, as described in some published articles.^9,17,18

There was no significant difference about number of complicated cases among the 3 groups (Table 1). We think that the reasons may be as follows: (1) we found out that some patients from subacute group were diagnosed TBAD in local centers and, after that, transferred to our center for further treatment. This hierarchical diagnosis and treatment system will ensure proper treatment for TBAD patients, but it will take time for the diagnosis and transfer. So, some “acute” patients will be grouped as “subacute” in our center. (2) We notice that some complicated presentations of subacute patients’ onset after 7 days since hospitalization. This factor will be related to the progression of TBAD and increase the number of complicated cases in subacute group.

Furthermore, among the 6 mortality of complicated group, 4 of them were distal malperfusion, 4 were impending rupture, 3 were resistant hypertension, 2 were persistent chest pain, and the staging was relatively homogeneous (2 acute, 3 subacute, 1 chronic). The results reveal that higher mortality of complicated cases may be related to some potential risk from low perfusion and organ disfunction, such as cardiac, brain, or kidney. Noncontrolled hypertension and its complications may also be risk factors of negative outcomes.

There are limitations to this study. The study was performed at a single center, and it was retrospective and nonrandomized. The results are likely not applicable to all types of dissections. There are still many other factors influence outcome of TEVAR, such as location of tears, involvement of supra-aortic arch branches (we exclude patients with this problem to balance the possible bias of the study), choice of stent graft, false lumen thrombosis status, morphological features such as taper ratio or aorta tortuosity, postoperational blood pressure and impulse control, which we did not include in our analysis. With respect to distal SINE prevention, restrictive bare stent was introduced for avoiding excessive distal oversizing since 2014.⁹ However, these patients were excluded to avoid excessive bias and possible confusion, and we did not present detailed discussion about restrictive bare stent or tapered stent, distal oversizing, and distal SINE prevention in this study. With respect to aortic remodeling, the cut-off between interval 2 (30–92 days) and chronic period (>92 days) should be considered with caution. Further study is strongly needed. In addition, as we did not discuss the potential relationship between TBAD staging and diverse human race (Caucasian or Asian), the suggestion about TBAD staging strategy and timing of TEVAR should be considered with caution. We hope that our results could raise discussion and further studies about possible strategy difference between Asian and Caucasian TBAD patients.

Conclusion

This study indicated that the mortality and aorta-related mortality rates and the incidence of proximal SINE were higher in patients with an acute TBAD than in those with a subacute or chronic TBAD after TEVAR. In addition, the capacity for aortic remodeling was lower in patients with a chronic TBAD. We suggested that the subacute stage (8–30 days) may be the optimal time to perform TEVAR in patients with an uncomplicated TBAD. The analysis also suggested that patients 8 to 14 days after dissection may be considered subacute, while those 31 to 92 days after dissection may be considered chronic.

Supplemental Material

sj-docx-1-jet-10.1177_15266028221098703 – Supplemental material for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection

Supplemental material, sj-docx-1-jet-10.1177_15266028221098703 for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection by Yang Zhao, Chen Yao, Henghui Yin, Mian Wang, Zilun Li, Jingsong Wang, Zuojun Hu, Shenming Wang and Guangqi Chang in Journal of Endovascular Therapy

Supplemental Material

sj-tif-2-jet-10.1177_15266028221098703 – Supplemental material for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection

Supplemental material, sj-tif-2-jet-10.1177_15266028221098703 for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection by Yang Zhao, Chen Yao, Henghui Yin, Mian Wang, Zilun Li, Jingsong Wang, Zuojun Hu, Shenming Wang and Guangqi Chang in Journal of Endovascular Therapy

Supplemental Material

sj-tif-3-jet-10.1177_15266028221098703 – Supplemental material for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection

Supplemental material, sj-tif-3-jet-10.1177_15266028221098703 for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection by Yang Zhao, Chen Yao, Henghui Yin, Mian Wang, Zilun Li, Jingsong Wang, Zuojun Hu, Shenming Wang and Guangqi Chang in Journal of Endovascular Therapy

Supplemental Material

sj-tif-4-jet-10.1177_15266028221098703 – Supplemental material for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection

Supplemental material, sj-tif-4-jet-10.1177_15266028221098703 for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection by Yang Zhao, Chen Yao, Henghui Yin, Mian Wang, Zilun Li, Jingsong Wang, Zuojun Hu, Shenming Wang and Guangqi Chang in Journal of Endovascular Therapy

Supplemental Material

sj-tif-5-jet-10.1177_15266028221098703 – Supplemental material for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection

Supplemental material, sj-tif-5-jet-10.1177_15266028221098703 for Prognosis and Remodeling after Endovascular Repair for Acute, Subacute, and Chronic Type B Aortic Dissection by Yang Zhao, Chen Yao, Henghui Yin, Mian Wang, Zilun Li, Jingsong Wang, Zuojun Hu, Shenming Wang and Guangqi Chang in Journal of Endovascular Therapy

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Mian Wang

Guangqi Chang

Supplemental Material

Supplemental material for this article is available online.

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