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Aortic Remodeling as a Prognostic Factor for Late Aortic Events After Thoracic Endovascular Aortic Repair in Type B Aortic Dissection With Patent False Lumen Yoshiki Watanabe, MD1; Kazuo Shimamura, MD, PhD1; Takuya Yoshida, MD1; Takashi Daimon, PhD2; Yukitoshi Shirakawa, MD, PhD1; Kei Torikai, MD, PhD1; Tomohiko Sakamoto, MD1; Takayuki Shijo, MD1; Koichi Toda, MD, PhD1; Toru Kuratani, MD, PhD1; and Yoshiki Sawa, MD, PhD1 1
Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, Osaka, Japan. 2Department of Biostatistics, Hyogo College of Medicine, Hyogo, Japan. ^
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Purpose: To assess the significance of aortic remodeling in the prevention of the late aortic events after thoracic endovascular aortic repair (TEVAR) for aortic dissection. Methods: The study involved 52 patients (41 men; mean age was 59.7613.3 years) with type B aortic dissections and patent false lumens treated with TEVAR between 2004 and 2011. Of the 52 patients, 18 were treated in the acute phase for rupture (n¼1), malperfusion (n¼10), aortic diameter over 40 mm at onset (n¼3), and rapid enlargement of the false lumen (n¼4). In the chronic setting, the indications for TEVAR were rupture (n¼1), malperfusion (n¼2), aortic diameter .50 mm (n¼18), and rapid enlargement of the false lumen (n¼13). Aortic remodeling was evaluated at 6 months postoperatively, and risk factors for late aortic events were evaluated in multivariate analysis using aortic remodeling and other pre-, peri-, and postoperative factors. Results: Over a mean 36.0618.9 months, 19 aortic events were documented: enlargement of the false lumen (n¼4), type I endoleak (n¼2), and erosion at the stent-graft edges (n¼13). Multivariate analysis revealed that failure to achieve aortic remodeling at 6 months postoperatively was the only significant risk factor for late aortic events (hazard ratio 0.20, p¼0.037). Patients with aortic remodeling had a higher rate of freedom from aortic events compared with those without aortic remodeling (100% vs. 81.5% at 1 year and 79.3% vs. 48.4% at 3 years, respectively). Conclusion: Aortic remodeling after TEVAR is a significant prognostic factor for better longterm results for type B aortic dissection. J Endovasc Ther. 2014;21:517–525 Key words: thoracic endovascular aortic repair, type B aortic dissection, aortic remodeling, stent-graft, patent false lumen, endoleak, false lumen enlargement ^ ^
Since it was first reported in 1999,1 thoracic endovascular aortic repair (TEVAR) for type B aortic dissection has emerged as a less invasive treatment for complicated acute aortic dissection. By closing the primary entry
tear using stent-grafts, the blood flow is redirected into the true lumen, resolving malperfusion and/or preventing rupture of the false lumen. Thus, this approach can provide a significant early treatment effect.2,3
The authors declare no association with any individual, company, or organization having a vested interest in the subject matter/products mentioned in this article. Corresponding author: Yoshiki Sawa, MD, PhD, Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. E-mail: [email protected] Q 2014 INTERNATIONAL SOCIETY
OF
ENDOVASCULAR SPECIALISTS
doi:10.1583/13-4646R.1
Available at www.jevt.org
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Moreover, primary entry closure facilitates thrombosis of the false lumen, which is followed by its regression and re-expansion of the true lumen. This late treatment effect, See commentary page 526 known as aortic remodeling,4,5 has the potential to prevent late aneurysmal degeneration or rupture of aortic dissection, which is observed in 20% to 50% of patients after conservative medical treatment.6–8 However, the effectiveness of aortic remodeling in preventing late aortic events has not yet been fully described. Among type B dissections, those with a patent false lumen, which has both a primary entry tear and a distal reentry, could have residual blood flow and pressurization of the false lumen from the distal reentry even after TEVAR. However, in the clinical setting, many patients with patent false lumens have aortic remodeling after TEVAR and good postoperative courses. Therefore, we considered whether aortic remodeling could predict long-term outcome in this morphology. In this study we evaluated the impact of aortic remodeling of patent false lumens on the prevention of the late aortic events after endovascular repair of type B dissection.
METHODS Study Design and Patient Cohort This retrospective study was approved by the institutional review board of our institution. Between 2004 and 2011, 175 TEVARs were performed for type B aortic dissection; from among these were selected patients with patent false lumen (double barrel)–type dissections without concomitant degenerative aortic disease. Patients with past ascending or arch interventions were excluded because they were mostly type A dissection originally (the original primary entry tear had been resected in most cases, and even if the entry tear remained, its location was very different from that of type B dissection). Patients with past descending or abdominal aortic interventions were also excluded because they could bias or make it fundamentally difficult to
Figure 1 ^ Flow chart showing patient selection in this study. TEVAR: thoracic endovascular aortic repair, CTA: computed tomographic angiography.
evaluate aortic remodeling. Lastly, patients who did not have complete series of computed tomographic angiograms (CTA) for analysis were not eligible, which left 52 patients (41 men; mean age was 59.7613.3 years) in this study (Fig. 1, Table 1). None of these patients had newly developed type B dissections after past interventions of the ascending or aortic arch aorta. Preoperative comorbidities included cerebrovascular disorders (n¼2), coronary artery disease (n¼6), chronic obstructive pulmonary disease (n¼1), and chronic renal failure (creatinine 1.5 mg/dL; n¼3). One patient had Marfan syndrome and another had Ehlers-Danlos syndrome. Indications for TEVAR in the 18 (34.6%) patients treated in the acute setting (within 14 days from dissection onset) were complications including malperfusion with end-organ ischemia (n¼12) and rupture (n¼2); there were also 4 uncomplicated but unstable dissections characterized by an aortic diameter over 40 mm at onset (n¼3) or rapid enlargement of the false lumen (n¼4). Of the 34 (65.4%) cases treated in the chronic phase, the indications for TEVAR were complications involving rupture (n¼1) and malperfusion with end-organ ischemia (n¼2) or uncomplicated but unstable cases with aortic diameter .50 mm (n¼18) or rapid aortic enlargement (.5 mm/year; n¼13). They all fulfilled the anatomical requirements for TEVAR in zone 1 or distally, including (1) a
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^ TABLE 1 Demographics and Characteristics of the 52 Study Patients Age, y Men Comorbidities Cerebrovascular disease Coronary artery disease Low cardiac function (EF ,40%) Chronic obstructive pulmonary disease Chronic renal failure* Peripheral artery disease Hypertension Diabetes mellitus Active smoker Steroid user Connective tissue disease/ Marfan syndrome ASA class I II III IV Maximum aortic diameter, mm Type IIIA Time from onset to TEVAR, mo
59.7613.3 41 (78%) 2 (3.8%) 6 (11.5%) 0 1 (1.9%) 3 0 21 3 8 2 2
(5.7%) (40.4%) (5.7%) (19.2%) (3.8%) (3.8%)/ 1 (1.9%)
10 (19.2%) 24 (46.1%) 8 (15.3%) 10 (19.2%) 47.9611.7 27 (52.9%) 22.4636.9
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^ Continuous data are presented as mean 6 standard deviation; categorical data are given as count (percentage). EF: ejection fraction, ASA: American Society of Anesthesiologists, TEVAR: thoracic endovascular aortic repair. * Creatinine . 1.5 mg/dL.
proximal sealing zone at least 2 cm from the entry tear, (2) a proximal aortic diameter ,37 mm, and (3) no severe atherosclerotic change in the landing zone.
Devices and Treatment Strategies In all cases, enhanced CTA was performed to scan the entire aorta, from the proximal supra-aortic vessels to the groin, with 1-mm collimation using 100 mL of a nonionic contrast agent injected continuously at a rate of 3 to 4 mL/s. The CT data were stored as Digital Imaging and Communications in Medicine (DICOM) datasets and analyzed using AquariusNET software (TeraRecon Inc., San Mateo, CA, USA). The stent-graft size was decided according to the diameters of both proximal and distal true lumens (derived from
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the perimeter of the true lumen) and oversized up to 10%. A tapered stent-graft or a combination of two different diameter stent-grafts was usually required to accommodate the difference between the proximal and distal diameters. The primary entry tear and all the intimal tears in the descending thoracic aorta were closed in a single procedure. The average length of the aorta covered was 120.3654.7 cm. Adjunct therapy for spinal cord protection including cerebrospinal fluid drainage and infusion of low-dose naloxone was given to 4 patients considered to be high risk of spinal cord injury [extensive aortic coverage from the left subclavian artery (LSA) to T-10 or bilateral hypogastric artery occlusion]. The proximal landing was in zone 1 in 2 cases, in zone 2 in 15 cases, and in zone 3 in the remaining 35. Supra-aortic branch revascularizations were performed simultaneously and included bypass grafting using axillobifemoral vascular grafts (Gore-Tex; W.L. Gore & Associates, Inc., Flagstaff, AZ, USA) in both zone 1 cases (Table 2). Six of the zone 2 cases underwent revascularization by right-to-left subclavian bypass and another by stenting (chimney technique). Before commercial stent-grafts were approved in Japan in 2008, homemade stentgrafts (n¼31) were used; these were composed of a Gianturco stent (William Cook Europe ApS, Bjaeverskov, Denmark) and a non-coated polyester fabric graft (J-Graft Woven Graft; Japan Lifeline, Tokyo, Japan). After 2008, TAG grafts (W.L. Gore & Associates, Inc.) were used in 4 (7.7%) patients, CTAG grafts (W.L. Gore and Associations, Inc.) in 5 (9.6%) patients, the Zenith TX2 TAA Endovascular Graft with Pro-Form (Cook Medical, Bloomington, IN, USA) in 1 (1.9%) patient, and the aortic extension device from the Excluder AAA Endoprosthesis (W.L. Gore & Associates, Inc.) in 5 (9.6%) patients; 6 patients required more than two types of devices.
Analysis of Aortic Remodeling In the analysis of aortic morphological change, the diameter of the entire aorta and the areas of the true and false lumens were
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^ TABLE 2 Details of the 52 TEVAR Procedures Preoperative CSF drainage Proximal landing zone 1 2 Distal to 2 Supra-aortic debranching or stenting Axillobifemoral–LCCA bypass Right-left LSA bypass LSA stenting Type of stent-graft Homemade only TAG only CTAG only Zenith TX2 only Aortic extension (Excluder) 2 types of devices Total covered length, cm
4 (7.7%) 2 (3.8%) 15 (28.8%) 35 (67.3%) 2 (3.8%) 6 (11.5%) 1 (1.9%)
Data were recorded using current reporting standards for endovascular aortic repair, prepared and revised by the Ad Hoc Committee for Standardized Reporting Practices in Vascular Surgery (Society for Vascular Surgery and the American Association for Vascular Surgery).10
Statistical Analysis
31 (59.6%) 4 (7.7%) 5 (9.6%) 1 (1.9%) 5 (9.6%) 6 (11.5%) 120.4654.7
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^ Continuous data are presented as mean 6 standard deviation; categorical data are given as count (percentage). TEVAR: thoracic endovascular aortic repair, CSF: cerebrospinal fluid, LCCA: left common carotid artery, LSA: left subclavian artery.
measured on preoperative and 6-month postoperative CTAs at the levels of the pulmonary artery bifurcation (PA), the distal edge of the stent-graft, T-10, the celiac axis, and the inferior mesenteric artery (IMA). Aortic remodeling was defined as a 20% increase in true lumen area in combination with a 20% decrease in false lumen area. Only the 6month scans were evaluated for remodeling because current guidelines recommend an initial surveillance period of 3 to 6 months after endovascular treatment,9 and 6 months has been considered to be sufficient for the aorta to remodel.
Late Aortic Events Late aortic events were recorded to evaluate their relevance to aortic remodeling. These included aortic rupture, sudden death from any unknown cause, and other major events that required reinterventions, such as late endoleak, false lumen dilatation, and aortic erosion (identified as a blood-filled pouch protruding into the thrombosed false lumen like an ulcer at the edge of the stentgraft).
Continuous variables are presented as mean 6 standard deviations; categorical variables are presented as frequencies with percentages. Survival and aortic event–free curves were plotted using the Kaplan-Meier method. Potential prognostic factors associated with aortic events were explored using a Cox proportional hazards model. Factors that were found to be statistically significant (p,0.05) in the univariate analyses were included in the multivariate analysis. Results are summarized as hazard ratios (HR) and 95% confidence intervals (CI). All p values were 2-sided, and p,0.05 was considered statistically significant. Data were analyzed using JMP statistical software (version 9.0.2; SAS Institute Inc., Cary, NC, USA).
RESULTS Primary technical success was achieved in all 52 patients, and no neurological complications, retrograde type A dissection, or iliac artery injury were observed. One patient required a tracheostomy, one had lower limb emboli, and another underwent total small bowel resection due to preoperative mesenteric ischemia (malperfusion). During a mean follow-up of 36.0618.9 months, 3 late deaths were documented owing to gallbladder carcinoma, heart failure, and sudden death. The overall survival rate was 97.6% at 1 year and 93.0% at 3 years (Fig. 2). Nineteen aortic events were documented, resulting in an 88.3% rate of freedom from aortic events at 1 year and 61.6% at 3 years. The aortic events included new minor type I endoleak (n¼2), aortic erosion at the proximal (n¼4) or distal (n¼9) edge of the stent-graft, and aortic enlargement with persistent distal false lumen perfusion (n¼4). The patients with
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additional TEVAR; a visceral debranching procedure was required in 2 cases. There were no procedure-related deaths among these reintervention patients.
Changes in Aortic Morphology
Figure 2 ^ Overall survival after thoracic endovascular aortic repair for type B aortic dissection.
a type I endoleak and 2 patients with aortic erosion at the proximal stent-graft edge were treated with open total arch replacement. The other 2 patients with aortic erosion at the proximal stent-graft edge and all the patients with aortic erosion at the distal edge were treated with additional TEVAR. Four cases of aortic enlargement were also treated by
Figure 3 shows the aortic diameters and the false and true lumen areas from the preoperative and 6-month postoperative CTA. The average total aortic diameter decreased at the PA bifurcation level but increased at all other levels of the aorta. The rates of aortic remodeling were 50% (25/50) at the PA level, 44.2% (23/52) at the level of the distal stent-graft end, 36.7% (18/49) at the T-10 level, 22.2% (10/45) at the celiac level, and 20.0% (7/35) at the IMA level.
Prognostic Factor Analysis of Aortic Events In the univariate analysis (Table 3), preoperative aortic diameter (p¼0.041) and an
Figure 3 ^ Changes in aortic morphology after TEVAR. PA: pulmonary artery bifurcation, SG: stent-graft, Th10: thoracic vertebra 10, IMA: inferior mesenteric artery. Error bars represent standard error of the mean.
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^ TABLE 3 Univariate and Multivariate Analysis of Aortic Events Univariate p Age Male gender CVD CAD COPD CRF Steroid usage Connective tissue disease Acute status Type IIIA Preoperative diameter Emergency Malperfusion Homemade stent-graft Device length 2 Stent-grafts Proximal landing at non dissected area Debranching Remodeling by level PA bifurcation Stent-graft distal end T-10 Celiac trunk
0.371 0.475 0.176 0.970 0.404 0.689 0.731 0.122 0.223 0.362 0.041 0.919 0.774 0.847 0.230 0.945 0.981 0.848 0.046 0.003 0.610 0.896
Multivariate
HR (95% CI) 1.02 1.47 3.27 1.02
1.83 0.66 1.04 1.07 1.17 0.90 1.01 1.03 0.99 1.12
(0.98 to (0.53 to (0.51 to (0.24 to —* (0.30 to (0.28 to —* (0.71 to (0.27 to (1.00 to (0.35 to (0.43 to (0.28 to (0.99 to (0.40 to (0.39 to (0.37 to
5.66) 1.61) 1.08) 4.61) 4.09) 2.47) 1.02) 2.98) 2.40) 4.83)
0.39 0.20 0.79 0.93
(0.14 (0.05 (0.29 (0.35
0.98) 0.61) 1.93) 2.91)
1.47 1.40
to to to to
p
HR (95% CI)
0.327
1.02 (0.98 to 1.05)
0.756 0.038
0.83 (0.28 to 3.01) 0.20 (0.04 to 0.92)
1.05) 5.19) 11.60) 3.06) 26.40) 25.40)
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^ HR: hazard ratio, CI: confidence interval, CVD: cerebrovascular disease, CAD: coronary artery disease, COPD: chronic obstructive pulmonary disease, CRF: chronic renal failure, SG: stent-graft, PA: pulmonary artery bifurcation. * No aortic event was observed in these patients.
absence of aortic remodeling at the PA level (p¼0.046) and the distal stent-graft end (p¼0.003) were associated with aortic events. Multivariate analysis identified only the absence of aortic remodeling at the distal stent-
graft terminus (HR 0.20, 95% CI 0.04 to 0.92, p¼0.038) as a significant prognostic factor associated with late aortic events. The rate of freedom from aortic events (Fig. 4) differed significantly between the patients with and without aortic remodeling (100% at 1 year and 81.5% at 3 years, respectively, vs. 79.3% at 1 year and 48.4% at 3 years, respectively; p¼0.037). No aortic events were noted in the descending aorta among the patients with aortic remodeling.
DISCUSSION
Figure 4 ^ Impact of aortic remodeling on eventfree survival after TEVAR for type B aortic dissection. *Cox proportional hazards model.
Aortic remodeling, described as the expansion of true lumen and thrombosis/regression of false lumen induced by successful entry closure with TEVAR, was considered to be the ideal postoperative morphological change of aortic dissection. Many investigators5,11–15 have described the incidence of aortic remod-
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eling or even the complete disappearance of the false lumen after entry closure with TEVAR, suggesting that this dramatic change may possibly represent the ‘‘healing’’ of aortic dissection. In addition, Mani et al.12 indicated a difference in the survival rate between patients with and without postoperative aortic remodeling after TEVAR for chronic aortic dissection. They reported superior survival probability in patients who achieved aortic remodeling, which they defined as a .0.5-cm reduction in the maximum descending aortic diameter from preoperative imaging to final follow-up, concluding that midterm survival is significantly related to aortic remodeling. Moreover, the randomized INSTEAD-XT trial conducted in patients undergoing TEVAR for chronic type B dissection reported a high rate of aortic remodeling compared to optimal medical treatment alone and demonstrated the benefit of TEVAR on late aorta-related mortality.14 The authors mentioned that aortic remodeling of the dissected aorta appears to be related to long-term vascular survival and that CT surveillance may be reduced once remodeling has been documented.13,14 These reports strongly suggest that aortic remodeling could prevent the development of late aortic complications, including aortic rupture, and may therefore increase survival; however, none of the reports indicated the direct impact of aortic remodeling on late outcomes. Therefore, the results of the present report investigating aortic remodeling as a prognostic factor for long-term outcome could help in establishing TEVAR treatment strategies for aortic dissection. We evaluated the relevance of aortic remodeling and late aortic events solely in patients with patent false lumens. A partially thrombosed false lumen, which is characterized by the lack of a distal reentry,11 would be completely thrombosed and depressurized when the primary entry was closed with the stent-graft. As for the totally thrombosed false lumen, these cases are generally indicated for surgery because of the extended aortic dilatation during follow-up, and these morphologies are very similar to those of extended degenerative aortic aneurysms, which need complete exclusion with blood sealing at the proximal and distal landing zones when
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treated endovascularly. In these two types of cases, we consider that there is no clinical advantage to observing long-term aortic remodeling if no endoleak has been documented. Unlike cases with a partially thrombosed or totally thrombosed false lumen, the patent false lumen would have residual blood flow from the distal reentry even after TEVAR, theoretically resulting in persistent pressurization. Therefore, we examined whether aortic remodeling could predict long-term outcome in this morphology. Recent studies2,3 reporting the satisfactory mid- to long-term results, including positive aortic remodeling, indicated that TEVAR is useful in the management of complications of acute type B dissection. The present results indicated that, when TEVAR induces aortic remodeling, it could also be a good treatment option for managing stable (uncomplicated) type B dissection. Therefore, achieving aortic remodeling is a critical issue for TEVAR in aortic dissection cases. Previous studies have reported that aortic remodeling after TEVAR for type B dissection is achieved in 12.5% to 79.2% of cases.5,12–16 The remodeling rate of 44.2% noted in the present study appears to be relatively low, which may be due to (1) involvement of a large number of patients with a chronic condition, (2) strict control of stent-graft oversizing up to 10% of the true lumen diameter, and (3) the evaluation of aortic remodeling shortly after TEVAR (at 6 months). Further, different definitions of aortic remodeling used in various studies, including a 5-mm decrease in maximum thoracic aortic diameter,5,12–14 a 10% decrease in total volume,15,16 or complete regression of the thoracic false lumen, 17 should be carefully considered when interpreting the differences in outcomes. Interestingly, several reports have indicated that the potential for achieving aortic remodeling following TEVAR is greater for acute (,2 weeks from onset) compared to chronic aortic dissection. The specific histological features in chronic dissection (many fenestrations between the true and the false channels and chronically scarred thick dissection flap) may be one of the reasons for the difficulty in achieving aortic remodeling; however, there may be several reasons contributing to this
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difference, and further investigations are required. The present study indicated that about half of the patients who failed to achieve aortic remodeling required further interventions to manage the continuously expanding false lumen (51.6% over 3 years). This necessity of secondary intervention should be considered when interpreting the good late survival rate (93.0% over 3 years) and absence of any dissection-related deaths in the present study. Other reports also state that secondary intervention rates ranged from 23.1% to 30.6%, 2,18 which suggests that a single TEVAR to close the primary entry may not be sufficient to manage aortic dissection in certain patients. However, deciding the time to perform further reintervention after initial TEVAR is not easy, particularly in patients with a stable false lumen (no progressive expansion). Therefore, it may be useful to check aortic remodeling at 6 months from the initial TEVAR to decide if further intervention is indicated. The most common reason for failure to achieve aortic remodeling could be continuous false lumen pressurization caused by blood flow from remaining intimal tears.19 Therefore, it is essential to have several options to close these remaining tears that usually exist in the thoracoabdominal aorta. TEVAR with visceral debranching and total endovascular repair with fenestrated/ branched devices, as well as coil embolization in the false lumen, are treatment options that are being investigated. A comprehensive endovascular treatment strategy, including the use of dissection-specific technology/techniques and thoracoabdominal re-entry closure only for patients at risk of developing a further aortic event, could make TEVAR the mainstream treatment for aortic dissections. As for the abdominal aorta, although the remodeling rate at the level of the abdominal aorta was low, enlargement of total aortic diameter during follow-up was not significant at that level. This may be because the absolute diameter of the abdominal aorta seemed to be small whenever blood flow in the false lumen remained.
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Limitations The present study is a retrospective observational study with a relatively small number of patients. Moreover, the devices used for TEVAR differed widely, including our homemade device.
Conclusion In the present study, we reported that aortic remodeling at 6 months after TEVAR for type B dissection is a prognostic factor for better long-term outcomes associated with fewer aortic events. This finding could be useful in determining the indication for secondary intervention and could contribute to establishing a treatment algorithm for type B aortic dissection. Acknowledgments: The authors wish to extend their thanks to all the members of the Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine.
REFERENCES 1. Dake MD, Kato N, Mitchell RS, et al. Endovascular stent-graft placement for the treatment of acute aortic dissection. N Engl J Med. 1999;340: 1546–1552. 2. Fattori R, Montgomery D, Lovato L, et al. Survival after endovascular therapy in patients with type B aortic dissection: a report from the International Registry of Acute Aortic Dissection (IRAD). JACC Cardiovasc Interv. 2013;6: 876–882. 3. Fattori R, Cao P, De Rango P, et al. Interdisciplinary expert consensus document on management of type B aortic dissection. J Am Coll Cardiol. 2013;61:1661–1678. 4. Conrad MF, Crawford RS, Kwolek CJ, et al. Aortic remodeling after endovascular repair of acute complicated type B aortic dissection. J Vasc Surg. 2009;50:510–517. 5. Sayer D, Bratby M, Brooks M, et al. Aortic morphology following endovascular repair of acute and chronic type B aortic dissection: implications for management. Eur J Vasc Endovasc Surg. 2008;36:522–529. 6. Trimarchi S, Nienaber CA, Rampoldi V, et al. Role and results of surgery in acute type B aortic dissection: insights from the International Registry of Acute Aortic Dissection (IRAD). Circulation. 2006;114:I357–364.
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7. Tsai TT, Fattori R, Trimarchi S, et al. Long-term survival in patients presenting with type B acute aortic dissection: insights from the International Registry of Acute Aortic Dissection. Circulation. 2006;114:2226–2231. 8. Schor JS, Yerlioglu ME, Galla JD, et al. Selective management of acute type B aortic dissection: long-term follow-up. Ann Thorac Surg. 1996;61:1339–1341. 9. Hirsch AT, Haskal ZJ, Hertzer NR, et al. ACC/ AHA 2005 Practice Guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic) Circulation. 2006;113:e463– 654. 10. Fillinger MF, Greenberg RK, McKinsey JF, et al. Reporting standards for thoracic endovascular aortic repair (TEVAR). J Vasc Surg. 2010;52: 1022–1033.e15. 11. Tsai TT, Evangelista A, Nienaber CA, et al. Partial thrombosis of the false lumen in patients with acute type B aortic dissection. N Engl J Med. 2007;357:349–359. 12. Mani K, Clough RE, Lyons OT, et al. Predictors of outcome after endovascular repair for chronic type B dissection. Eur J Vasc Endovasc Surg. 2012;43:386–391. 13. Nienaber CA, Kische S, Rousseau H, et al. Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt
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Grafts in Aortic Dissection (INSTEAD) trial. Circulation. 2009;120:2519–2528. 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. Melissano G, Bertoglio L, Rinaldi E, et al. Volume changes in aortic true and false lumen after the ‘‘PETTICOAT’’ procedure for type B aortic dissection. J Vasc Surg. 2012;55:641– 651. Qing KX, Yiu WK, Cheng SW. A morphologic study of chronic type B aortic dissections and aneurysms after thoracic endovascular stent grafting. J Vasc Surg. 2012;55:1268–1275. 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. Leshnower BG, Szeto WY, Pochettino A, et al. Thoracic endografting reduces morbidity and remodels the thoracic aorta in DeBakey III aneurysms. Ann Thorac Surg. 2013;95:914– 921. Svensson LG, Kouchoukos NT, Miller DC, et al. Expert consensus document on the treatment of descending thoracic aortic disease using endovascular stent-grafts. Ann Thorac Surg. 2008;85(1 Suppl):S1–41.
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Aortic Remodeling as a Prognostic Factor for Late Aortic Events After Thoracic Endovascular Aortic Repair in Type B Aortic Dissection With Patent False Lumen Yoshiki Watanabe, MD1; Kazuo Shimamura, MD, PhD1; Takuya Yoshida, MD1; Takashi Daimon, PhD2; Yukitoshi Shirakawa, MD, PhD1; Kei Torikai, MD, PhD1; Tomohiko Sakamoto, MD1; Takayuki Shijo, MD1; Koichi Toda, MD, PhD1; Toru Kuratani, MD, PhD1; and Yoshiki Sawa, MD, PhD1 1
Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, Osaka, Japan. 2Department of Biostatistics, Hyogo College of Medicine, Hyogo, Japan. ^
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Purpose: To assess the significance of aortic remodeling in the prevention of the late aortic events after thoracic endovascular aortic repair (TEVAR) for aortic dissection. Methods: The study involved 52 patients (41 men; mean age was 59.7613.3 years) with type B aortic dissections and patent false lumens treated with TEVAR between 2004 and 2011. Of the 52 patients, 18 were treated in the acute phase for rupture (n¼1), malperfusion (n¼10), aortic diameter over 40 mm at onset (n¼3), and rapid enlargement of the false lumen (n¼4). In the chronic setting, the indications for TEVAR were rupture (n¼1), malperfusion (n¼2), aortic diameter .50 mm (n¼18), and rapid enlargement of the false lumen (n¼13). Aortic remodeling was evaluated at 6 months postoperatively, and risk factors for late aortic events were evaluated in multivariate analysis using aortic remodeling and other pre-, peri-, and postoperative factors. Results: Over a mean 36.0618.9 months, 19 aortic events were documented: enlargement of the false lumen (n¼4), type I endoleak (n¼2), and erosion at the stent-graft edges (n¼13). Multivariate analysis revealed that failure to achieve aortic remodeling at 6 months postoperatively was the only significant risk factor for late aortic events (hazard ratio 0.20, p¼0.037). Patients with aortic remodeling had a higher rate of freedom from aortic events compared with those without aortic remodeling (100% vs. 81.5% at 1 year and 79.3% vs. 48.4% at 3 years, respectively). Conclusion: Aortic remodeling after TEVAR is a significant prognostic factor for better longterm results for type B aortic dissection. J Endovasc Ther. 2014;21:517–525 Key words: thoracic endovascular aortic repair, type B aortic dissection, aortic remodeling, stent-graft, patent false lumen, endoleak, false lumen enlargement ^ ^
Since it was first reported in 1999,1 thoracic endovascular aortic repair (TEVAR) for type B aortic dissection has emerged as a less invasive treatment for complicated acute aortic dissection. By closing the primary entry
tear using stent-grafts, the blood flow is redirected into the true lumen, resolving malperfusion and/or preventing rupture of the false lumen. Thus, this approach can provide a significant early treatment effect.2,3
The authors declare no association with any individual, company, or organization having a vested interest in the subject matter/products mentioned in this article. Corresponding author: Yoshiki Sawa, MD, PhD, Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. E-mail: [email protected] Q 2014 INTERNATIONAL SOCIETY
OF
ENDOVASCULAR SPECIALISTS
doi:10.1583/13-4646R.1
Available at www.jevt.org
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Moreover, primary entry closure facilitates thrombosis of the false lumen, which is followed by its regression and re-expansion of the true lumen. This late treatment effect, See commentary page 526 known as aortic remodeling,4,5 has the potential to prevent late aneurysmal degeneration or rupture of aortic dissection, which is observed in 20% to 50% of patients after conservative medical treatment.6–8 However, the effectiveness of aortic remodeling in preventing late aortic events has not yet been fully described. Among type B dissections, those with a patent false lumen, which has both a primary entry tear and a distal reentry, could have residual blood flow and pressurization of the false lumen from the distal reentry even after TEVAR. However, in the clinical setting, many patients with patent false lumens have aortic remodeling after TEVAR and good postoperative courses. Therefore, we considered whether aortic remodeling could predict long-term outcome in this morphology. In this study we evaluated the impact of aortic remodeling of patent false lumens on the prevention of the late aortic events after endovascular repair of type B dissection.
METHODS Study Design and Patient Cohort This retrospective study was approved by the institutional review board of our institution. Between 2004 and 2011, 175 TEVARs were performed for type B aortic dissection; from among these were selected patients with patent false lumen (double barrel)–type dissections without concomitant degenerative aortic disease. Patients with past ascending or arch interventions were excluded because they were mostly type A dissection originally (the original primary entry tear had been resected in most cases, and even if the entry tear remained, its location was very different from that of type B dissection). Patients with past descending or abdominal aortic interventions were also excluded because they could bias or make it fundamentally difficult to
Figure 1 ^ Flow chart showing patient selection in this study. TEVAR: thoracic endovascular aortic repair, CTA: computed tomographic angiography.
evaluate aortic remodeling. Lastly, patients who did not have complete series of computed tomographic angiograms (CTA) for analysis were not eligible, which left 52 patients (41 men; mean age was 59.7613.3 years) in this study (Fig. 1, Table 1). None of these patients had newly developed type B dissections after past interventions of the ascending or aortic arch aorta. Preoperative comorbidities included cerebrovascular disorders (n¼2), coronary artery disease (n¼6), chronic obstructive pulmonary disease (n¼1), and chronic renal failure (creatinine 1.5 mg/dL; n¼3). One patient had Marfan syndrome and another had Ehlers-Danlos syndrome. Indications for TEVAR in the 18 (34.6%) patients treated in the acute setting (within 14 days from dissection onset) were complications including malperfusion with end-organ ischemia (n¼12) and rupture (n¼2); there were also 4 uncomplicated but unstable dissections characterized by an aortic diameter over 40 mm at onset (n¼3) or rapid enlargement of the false lumen (n¼4). Of the 34 (65.4%) cases treated in the chronic phase, the indications for TEVAR were complications involving rupture (n¼1) and malperfusion with end-organ ischemia (n¼2) or uncomplicated but unstable cases with aortic diameter .50 mm (n¼18) or rapid aortic enlargement (.5 mm/year; n¼13). They all fulfilled the anatomical requirements for TEVAR in zone 1 or distally, including (1) a
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^ TABLE 1 Demographics and Characteristics of the 52 Study Patients Age, y Men Comorbidities Cerebrovascular disease Coronary artery disease Low cardiac function (EF ,40%) Chronic obstructive pulmonary disease Chronic renal failure* Peripheral artery disease Hypertension Diabetes mellitus Active smoker Steroid user Connective tissue disease/ Marfan syndrome ASA class I II III IV Maximum aortic diameter, mm Type IIIA Time from onset to TEVAR, mo
59.7613.3 41 (78%) 2 (3.8%) 6 (11.5%) 0 1 (1.9%) 3 0 21 3 8 2 2
(5.7%) (40.4%) (5.7%) (19.2%) (3.8%) (3.8%)/ 1 (1.9%)
10 (19.2%) 24 (46.1%) 8 (15.3%) 10 (19.2%) 47.9611.7 27 (52.9%) 22.4636.9
^
^ Continuous data are presented as mean 6 standard deviation; categorical data are given as count (percentage). EF: ejection fraction, ASA: American Society of Anesthesiologists, TEVAR: thoracic endovascular aortic repair. * Creatinine . 1.5 mg/dL.
proximal sealing zone at least 2 cm from the entry tear, (2) a proximal aortic diameter ,37 mm, and (3) no severe atherosclerotic change in the landing zone.
Devices and Treatment Strategies In all cases, enhanced CTA was performed to scan the entire aorta, from the proximal supra-aortic vessels to the groin, with 1-mm collimation using 100 mL of a nonionic contrast agent injected continuously at a rate of 3 to 4 mL/s. The CT data were stored as Digital Imaging and Communications in Medicine (DICOM) datasets and analyzed using AquariusNET software (TeraRecon Inc., San Mateo, CA, USA). The stent-graft size was decided according to the diameters of both proximal and distal true lumens (derived from
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the perimeter of the true lumen) and oversized up to 10%. A tapered stent-graft or a combination of two different diameter stent-grafts was usually required to accommodate the difference between the proximal and distal diameters. The primary entry tear and all the intimal tears in the descending thoracic aorta were closed in a single procedure. The average length of the aorta covered was 120.3654.7 cm. Adjunct therapy for spinal cord protection including cerebrospinal fluid drainage and infusion of low-dose naloxone was given to 4 patients considered to be high risk of spinal cord injury [extensive aortic coverage from the left subclavian artery (LSA) to T-10 or bilateral hypogastric artery occlusion]. The proximal landing was in zone 1 in 2 cases, in zone 2 in 15 cases, and in zone 3 in the remaining 35. Supra-aortic branch revascularizations were performed simultaneously and included bypass grafting using axillobifemoral vascular grafts (Gore-Tex; W.L. Gore & Associates, Inc., Flagstaff, AZ, USA) in both zone 1 cases (Table 2). Six of the zone 2 cases underwent revascularization by right-to-left subclavian bypass and another by stenting (chimney technique). Before commercial stent-grafts were approved in Japan in 2008, homemade stentgrafts (n¼31) were used; these were composed of a Gianturco stent (William Cook Europe ApS, Bjaeverskov, Denmark) and a non-coated polyester fabric graft (J-Graft Woven Graft; Japan Lifeline, Tokyo, Japan). After 2008, TAG grafts (W.L. Gore & Associates, Inc.) were used in 4 (7.7%) patients, CTAG grafts (W.L. Gore and Associations, Inc.) in 5 (9.6%) patients, the Zenith TX2 TAA Endovascular Graft with Pro-Form (Cook Medical, Bloomington, IN, USA) in 1 (1.9%) patient, and the aortic extension device from the Excluder AAA Endoprosthesis (W.L. Gore & Associates, Inc.) in 5 (9.6%) patients; 6 patients required more than two types of devices.
Analysis of Aortic Remodeling In the analysis of aortic morphological change, the diameter of the entire aorta and the areas of the true and false lumens were
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^ TABLE 2 Details of the 52 TEVAR Procedures Preoperative CSF drainage Proximal landing zone 1 2 Distal to 2 Supra-aortic debranching or stenting Axillobifemoral–LCCA bypass Right-left LSA bypass LSA stenting Type of stent-graft Homemade only TAG only CTAG only Zenith TX2 only Aortic extension (Excluder) 2 types of devices Total covered length, cm
4 (7.7%) 2 (3.8%) 15 (28.8%) 35 (67.3%) 2 (3.8%) 6 (11.5%) 1 (1.9%)
Data were recorded using current reporting standards for endovascular aortic repair, prepared and revised by the Ad Hoc Committee for Standardized Reporting Practices in Vascular Surgery (Society for Vascular Surgery and the American Association for Vascular Surgery).10
Statistical Analysis
31 (59.6%) 4 (7.7%) 5 (9.6%) 1 (1.9%) 5 (9.6%) 6 (11.5%) 120.4654.7
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^ Continuous data are presented as mean 6 standard deviation; categorical data are given as count (percentage). TEVAR: thoracic endovascular aortic repair, CSF: cerebrospinal fluid, LCCA: left common carotid artery, LSA: left subclavian artery.
measured on preoperative and 6-month postoperative CTAs at the levels of the pulmonary artery bifurcation (PA), the distal edge of the stent-graft, T-10, the celiac axis, and the inferior mesenteric artery (IMA). Aortic remodeling was defined as a 20% increase in true lumen area in combination with a 20% decrease in false lumen area. Only the 6month scans were evaluated for remodeling because current guidelines recommend an initial surveillance period of 3 to 6 months after endovascular treatment,9 and 6 months has been considered to be sufficient for the aorta to remodel.
Late Aortic Events Late aortic events were recorded to evaluate their relevance to aortic remodeling. These included aortic rupture, sudden death from any unknown cause, and other major events that required reinterventions, such as late endoleak, false lumen dilatation, and aortic erosion (identified as a blood-filled pouch protruding into the thrombosed false lumen like an ulcer at the edge of the stentgraft).
Continuous variables are presented as mean 6 standard deviations; categorical variables are presented as frequencies with percentages. Survival and aortic event–free curves were plotted using the Kaplan-Meier method. Potential prognostic factors associated with aortic events were explored using a Cox proportional hazards model. Factors that were found to be statistically significant (p,0.05) in the univariate analyses were included in the multivariate analysis. Results are summarized as hazard ratios (HR) and 95% confidence intervals (CI). All p values were 2-sided, and p,0.05 was considered statistically significant. Data were analyzed using JMP statistical software (version 9.0.2; SAS Institute Inc., Cary, NC, USA).
RESULTS Primary technical success was achieved in all 52 patients, and no neurological complications, retrograde type A dissection, or iliac artery injury were observed. One patient required a tracheostomy, one had lower limb emboli, and another underwent total small bowel resection due to preoperative mesenteric ischemia (malperfusion). During a mean follow-up of 36.0618.9 months, 3 late deaths were documented owing to gallbladder carcinoma, heart failure, and sudden death. The overall survival rate was 97.6% at 1 year and 93.0% at 3 years (Fig. 2). Nineteen aortic events were documented, resulting in an 88.3% rate of freedom from aortic events at 1 year and 61.6% at 3 years. The aortic events included new minor type I endoleak (n¼2), aortic erosion at the proximal (n¼4) or distal (n¼9) edge of the stent-graft, and aortic enlargement with persistent distal false lumen perfusion (n¼4). The patients with
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additional TEVAR; a visceral debranching procedure was required in 2 cases. There were no procedure-related deaths among these reintervention patients.
Changes in Aortic Morphology
Figure 2 ^ Overall survival after thoracic endovascular aortic repair for type B aortic dissection.
a type I endoleak and 2 patients with aortic erosion at the proximal stent-graft edge were treated with open total arch replacement. The other 2 patients with aortic erosion at the proximal stent-graft edge and all the patients with aortic erosion at the distal edge were treated with additional TEVAR. Four cases of aortic enlargement were also treated by
Figure 3 shows the aortic diameters and the false and true lumen areas from the preoperative and 6-month postoperative CTA. The average total aortic diameter decreased at the PA bifurcation level but increased at all other levels of the aorta. The rates of aortic remodeling were 50% (25/50) at the PA level, 44.2% (23/52) at the level of the distal stent-graft end, 36.7% (18/49) at the T-10 level, 22.2% (10/45) at the celiac level, and 20.0% (7/35) at the IMA level.
Prognostic Factor Analysis of Aortic Events In the univariate analysis (Table 3), preoperative aortic diameter (p¼0.041) and an
Figure 3 ^ Changes in aortic morphology after TEVAR. PA: pulmonary artery bifurcation, SG: stent-graft, Th10: thoracic vertebra 10, IMA: inferior mesenteric artery. Error bars represent standard error of the mean.
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^
^ TABLE 3 Univariate and Multivariate Analysis of Aortic Events Univariate p Age Male gender CVD CAD COPD CRF Steroid usage Connective tissue disease Acute status Type IIIA Preoperative diameter Emergency Malperfusion Homemade stent-graft Device length 2 Stent-grafts Proximal landing at non dissected area Debranching Remodeling by level PA bifurcation Stent-graft distal end T-10 Celiac trunk
0.371 0.475 0.176 0.970 0.404 0.689 0.731 0.122 0.223 0.362 0.041 0.919 0.774 0.847 0.230 0.945 0.981 0.848 0.046 0.003 0.610 0.896
Multivariate
HR (95% CI) 1.02 1.47 3.27 1.02
1.83 0.66 1.04 1.07 1.17 0.90 1.01 1.03 0.99 1.12
(0.98 to (0.53 to (0.51 to (0.24 to —* (0.30 to (0.28 to —* (0.71 to (0.27 to (1.00 to (0.35 to (0.43 to (0.28 to (0.99 to (0.40 to (0.39 to (0.37 to
5.66) 1.61) 1.08) 4.61) 4.09) 2.47) 1.02) 2.98) 2.40) 4.83)
0.39 0.20 0.79 0.93
(0.14 (0.05 (0.29 (0.35
0.98) 0.61) 1.93) 2.91)
1.47 1.40
to to to to
p
HR (95% CI)
0.327
1.02 (0.98 to 1.05)
0.756 0.038
0.83 (0.28 to 3.01) 0.20 (0.04 to 0.92)
1.05) 5.19) 11.60) 3.06) 26.40) 25.40)
^
^ HR: hazard ratio, CI: confidence interval, CVD: cerebrovascular disease, CAD: coronary artery disease, COPD: chronic obstructive pulmonary disease, CRF: chronic renal failure, SG: stent-graft, PA: pulmonary artery bifurcation. * No aortic event was observed in these patients.
absence of aortic remodeling at the PA level (p¼0.046) and the distal stent-graft end (p¼0.003) were associated with aortic events. Multivariate analysis identified only the absence of aortic remodeling at the distal stent-
graft terminus (HR 0.20, 95% CI 0.04 to 0.92, p¼0.038) as a significant prognostic factor associated with late aortic events. The rate of freedom from aortic events (Fig. 4) differed significantly between the patients with and without aortic remodeling (100% at 1 year and 81.5% at 3 years, respectively, vs. 79.3% at 1 year and 48.4% at 3 years, respectively; p¼0.037). No aortic events were noted in the descending aorta among the patients with aortic remodeling.
DISCUSSION
Figure 4 ^ Impact of aortic remodeling on eventfree survival after TEVAR for type B aortic dissection. *Cox proportional hazards model.
Aortic remodeling, described as the expansion of true lumen and thrombosis/regression of false lumen induced by successful entry closure with TEVAR, was considered to be the ideal postoperative morphological change of aortic dissection. Many investigators5,11–15 have described the incidence of aortic remod-
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eling or even the complete disappearance of the false lumen after entry closure with TEVAR, suggesting that this dramatic change may possibly represent the ‘‘healing’’ of aortic dissection. In addition, Mani et al.12 indicated a difference in the survival rate between patients with and without postoperative aortic remodeling after TEVAR for chronic aortic dissection. They reported superior survival probability in patients who achieved aortic remodeling, which they defined as a .0.5-cm reduction in the maximum descending aortic diameter from preoperative imaging to final follow-up, concluding that midterm survival is significantly related to aortic remodeling. Moreover, the randomized INSTEAD-XT trial conducted in patients undergoing TEVAR for chronic type B dissection reported a high rate of aortic remodeling compared to optimal medical treatment alone and demonstrated the benefit of TEVAR on late aorta-related mortality.14 The authors mentioned that aortic remodeling of the dissected aorta appears to be related to long-term vascular survival and that CT surveillance may be reduced once remodeling has been documented.13,14 These reports strongly suggest that aortic remodeling could prevent the development of late aortic complications, including aortic rupture, and may therefore increase survival; however, none of the reports indicated the direct impact of aortic remodeling on late outcomes. Therefore, the results of the present report investigating aortic remodeling as a prognostic factor for long-term outcome could help in establishing TEVAR treatment strategies for aortic dissection. We evaluated the relevance of aortic remodeling and late aortic events solely in patients with patent false lumens. A partially thrombosed false lumen, which is characterized by the lack of a distal reentry,11 would be completely thrombosed and depressurized when the primary entry was closed with the stent-graft. As for the totally thrombosed false lumen, these cases are generally indicated for surgery because of the extended aortic dilatation during follow-up, and these morphologies are very similar to those of extended degenerative aortic aneurysms, which need complete exclusion with blood sealing at the proximal and distal landing zones when
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treated endovascularly. In these two types of cases, we consider that there is no clinical advantage to observing long-term aortic remodeling if no endoleak has been documented. Unlike cases with a partially thrombosed or totally thrombosed false lumen, the patent false lumen would have residual blood flow from the distal reentry even after TEVAR, theoretically resulting in persistent pressurization. Therefore, we examined whether aortic remodeling could predict long-term outcome in this morphology. Recent studies2,3 reporting the satisfactory mid- to long-term results, including positive aortic remodeling, indicated that TEVAR is useful in the management of complications of acute type B dissection. The present results indicated that, when TEVAR induces aortic remodeling, it could also be a good treatment option for managing stable (uncomplicated) type B dissection. Therefore, achieving aortic remodeling is a critical issue for TEVAR in aortic dissection cases. Previous studies have reported that aortic remodeling after TEVAR for type B dissection is achieved in 12.5% to 79.2% of cases.5,12–16 The remodeling rate of 44.2% noted in the present study appears to be relatively low, which may be due to (1) involvement of a large number of patients with a chronic condition, (2) strict control of stent-graft oversizing up to 10% of the true lumen diameter, and (3) the evaluation of aortic remodeling shortly after TEVAR (at 6 months). Further, different definitions of aortic remodeling used in various studies, including a 5-mm decrease in maximum thoracic aortic diameter,5,12–14 a 10% decrease in total volume,15,16 or complete regression of the thoracic false lumen, 17 should be carefully considered when interpreting the differences in outcomes. Interestingly, several reports have indicated that the potential for achieving aortic remodeling following TEVAR is greater for acute (,2 weeks from onset) compared to chronic aortic dissection. The specific histological features in chronic dissection (many fenestrations between the true and the false channels and chronically scarred thick dissection flap) may be one of the reasons for the difficulty in achieving aortic remodeling; however, there may be several reasons contributing to this
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difference, and further investigations are required. The present study indicated that about half of the patients who failed to achieve aortic remodeling required further interventions to manage the continuously expanding false lumen (51.6% over 3 years). This necessity of secondary intervention should be considered when interpreting the good late survival rate (93.0% over 3 years) and absence of any dissection-related deaths in the present study. Other reports also state that secondary intervention rates ranged from 23.1% to 30.6%, 2,18 which suggests that a single TEVAR to close the primary entry may not be sufficient to manage aortic dissection in certain patients. However, deciding the time to perform further reintervention after initial TEVAR is not easy, particularly in patients with a stable false lumen (no progressive expansion). Therefore, it may be useful to check aortic remodeling at 6 months from the initial TEVAR to decide if further intervention is indicated. The most common reason for failure to achieve aortic remodeling could be continuous false lumen pressurization caused by blood flow from remaining intimal tears.19 Therefore, it is essential to have several options to close these remaining tears that usually exist in the thoracoabdominal aorta. TEVAR with visceral debranching and total endovascular repair with fenestrated/ branched devices, as well as coil embolization in the false lumen, are treatment options that are being investigated. A comprehensive endovascular treatment strategy, including the use of dissection-specific technology/techniques and thoracoabdominal re-entry closure only for patients at risk of developing a further aortic event, could make TEVAR the mainstream treatment for aortic dissections. As for the abdominal aorta, although the remodeling rate at the level of the abdominal aorta was low, enlargement of total aortic diameter during follow-up was not significant at that level. This may be because the absolute diameter of the abdominal aorta seemed to be small whenever blood flow in the false lumen remained.
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Limitations The present study is a retrospective observational study with a relatively small number of patients. Moreover, the devices used for TEVAR differed widely, including our homemade device.
Conclusion In the present study, we reported that aortic remodeling at 6 months after TEVAR for type B dissection is a prognostic factor for better long-term outcomes associated with fewer aortic events. This finding could be useful in determining the indication for secondary intervention and could contribute to establishing a treatment algorithm for type B aortic dissection. Acknowledgments: The authors wish to extend their thanks to all the members of the Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine.
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