Multicenter Clinical Trial of the Conformable Stent Graft for the Treatment of Acute, Complicated Type B Dissection

Objective: The treatment of acute, complicated type B aortic dissection has evolved in the past several decades. Thoracic endovascular aortic repair when anatomy is suitable, has been regarded as the preferable treatment to seal the primary entry tear, redirect and re-establish adequate true lumen flow, and thereby promote aortic remodeling. This study was designed to determine the safety and efficacy of a conformable thoracic endoprosthesis device for patients with acute, complicated type B aortic dissection, defined as malperfusion or rupture or both.

Methods: Between January 2010 and January 2012, 50 patients with complicated type B aortic dissection from 26 sites in the United States were included in this prospective, multicenter, nonrandomized single-arm study. The primary safety end point was all-cause mortality through 30 days after treatment, and the primary efficacy end point was exclusion of the primary entry tear (Core Laboratory adjudicated) at 1-month follow-up. Secondary end points included false lumen thrombosis, dissection-based reintervention rate, and aortic rupture.

Results: All device implants were successfully completed. Six patients (12%) required additional device implantations ≤1 year from the index procedure. There was no conversion to open repair at 1 year. Exclusion of the primary entry tear at 30 days occurred in 97.5% of patients. All-cause mortality through 30 days was 8%. Survival was 88% at 1 year and 85% at 2 years. At 1 year after treatment, 35.1% of patients had experienced a decrease of ≥5 mm in overall diameter in the treated segment of the aorta. From pretreatment to the 36-month follow-up, the average minimum true lumen area increased by 206.3 mm(2), and the average maximum false lumen area decreased by 313.4 mm(2). The 30-day stroke rate was 18%; none were fatal, and one permanent deficit occurred. Four patients (8%) experienced spinal cord ischemia of any severity but without any permanent or significant deficits. New aortic dissection (3 retrograde, 2 de novo) occurred in five patients (10%). The secondary intervention rate was 18%.

Conclusions: Treatment with the conformable thoracic endovascular aortic repair device produced favorable perioperative and intermediate level clinical and anatomic outcomes. In particular, an operative mortality of 8% in this cohort is comparable to that noted in a Society for Vascular Surgery objective performance criteria publication. Late survival in our cohort compares favorably with historical data referable to complicated type B dissection.