Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial

Abstract

Background: Thoracic endovascular aortic repair (TEVAR) represents a novel concept for type B aortic dissection. Although life-saving in acute emergencies, outcomes and survival of TEVAR in stable dissection are unknown.

Methods and results: One hundred forty patients in stable clinical condition at least 2 weeks after index dissection were randomly subjected to elective stent-graft placement in addition to optimal medical therapy (n=72) or to optimal medical therapy alone (n=68) with surveillance (arterial pressure according to World Health Organization guidelines < or =120/80 mm Hg). The primary end point was all-cause death at 2 years, whereas aorta-related death, progression (with need for conversion or additional endovascular or open surgery), and aortic remodeling were secondary end points. There was no difference in all-cause deaths, with a 2-year cumulative survival rate of 95.6+/-2.5% with optimal medical therapy versus 88.9+/-3.7% with TEVAR (P=0.15); the trial, however, turned out to be underpowered. Moreover, the aorta-related death rate was not different (P=0.44), and the risk for the combined end point of aorta-related death (rupture) and progression (including conversion or additional endovascular or open surgery) was similar (P=0.65). Three neurological adverse events occurred in the TEVAR group (1 paraplegia, 1 stroke, and 1 transient paraparesis), versus 1 case of paraparesis with medical treatment. Finally, aortic remodeling (with true-lumen recovery and thoracic false-lumen thrombosis) occurred in 91.3% of patients with TEVAR versus 19.4% of those who received medical treatment (P<0.001), which suggests ongoing aortic remodeling.

Conclusions: In the first randomized study on elective stent-graft placement in survivors of uncomplicated type B aortic dissection, TEVAR failed to improve 2-year survival and adverse event rates despite favorable aortic remodeling.

Trial registration: ClinicalTrials.gov NCT00525356.