Impact of proximal seal zone length and intramural hematoma on clinical outcomes and aortic remodeling after thoracic endovascular aortic repair for aortic dissections.

Objective: Thoracic endovascular aortic repair (TEVAR) has become standard treatment of complicated type B aortic dissections (TBADs). Whereas adequate proximal seal is a fundamental requisite for TEVAR, what constitutes "adequate" in dissections and its impact on outcomes remain unclear. The goal of this study was to describe the proximal seal zone achieved with associated clinical outcomes and aortic remodeling.

Methods: A retrospective review was performed of TEVARs for TBAD at a single institution from 2006 to 2016. Three-dimensional centerline analysis of preoperative computed tomography was used to identify the primary entry tear, dissection extent, distances between arch branches, and intramural hematoma (IMH) involvement of the proximal seal zone. Patients were categorized into group A, those with proximal extent of seal zone in IMH/dissection-free aorta, and group B, those with landing zone entirely within IMH. Clinical outcomes including retrograde type A dissection (RTAD), death, and aortic reinterventions were recorded. Postoperative computed tomography scans were analyzed for remodeling of the true and false lumen volumes of the thoracic aorta.

Results: Seventy-one patients who underwent TEVAR for TBAD were reviewed. Indications for TEVAR included malperfusion, aneurysm, persistent pain, rupture, uncontrolled hypertension, and other. Mean follow-up was 14 months. In 26 (37%) patients, the proximal extent of the seal zone was without IMH, whereas 45 (63%) patients had proximal seal zone entirely in IMH. Proximal seal zone of 2-cm IMH-free aorta was achieved in only six (8.5%) patients. Review of arch anatomy revealed that to create a 2-cm landing zone of IMH-free aorta, 31 (43.7%) patients would have required coverage of all three arch branch vessels. Postoperatively, two patients developed image-proven RTADs requiring open repair, and one patient had sudden death. All three of these patients had TEVAR with the proximal seal zone entirely in IMH. No RTADs occurred in patients whose proximal seal zone involved healthy aortic segment. At 24 months, overall survival was 93% and freedom from aorta-related mortality was 97.4%. Complete thoracic false lumen thrombosis was seen in 46% of patients. Aortic remodeling, such as true lumen expansion, false lumen regression, and false lumen thrombosis, was similar in both groups of patients.

Conclusions: Whereas achieving 2 cm of IMH-free proximal seal zone during TEVAR for TBAD would often require extensive arch branch coverage, failure to achieve any IMH-free proximal seal zone may be associated with higher incidence of RTAD. The length and quality of the proximal seal zone did not affect the subsequent aortic remodeling after TEVAR.