NEW YORK – Five-year results from the INSTEAD trial showed that patients with stable type B aortic dissections who were randomized to receive thoracic endovascular aneurysm repair plus optimal medical treatment showed significantly less aorta-specific mortality and delayed disease progression than did those who received OMT alone, according to Rachel Clough, Ph.D., MRCS, who presented the findings at the AATS 2014 Aortic Symposium.
The results indicate that delayed adverse events, such as sudden fatalities, expansion of the false lumen, rupture, and other late complications that occur in patients treated medically in the years subsequent to dissection, are prevented or attenuated with stent grafts.
"Uncomplicated patients with type B aortic dissection have traditionally been treated with antihypertensive medication but what we see is, even in patients with very good blood pressure control, there is a continued attrition rate looking out toward 5 years. In some series, more than 50% of patients are dead [at that time point]," said Dr. Clough of King’s College London.
INSTEAD (Investigation of Stent Grafts in Aortic Dissection) is the first randomized trial comparing thoracic endovascular aneurysm repair (TEVAR) with a stent graft. When 2-year results were published in 2009 (Circulation 2009;120:2519-28), there was criticism that the study was underpowered as no differences were seen in all-cause deaths, aorta-related deaths due to aortic rupture, or dissection progression plus rupture. There was even a trend toward better cumulative survival in the OMT group.
Sixty-eight patients were randomized to receive OMT and 72 patients received TEVAR plus OMT. Eighty-three percent had one stent placed, 11% had two stents, and 6% had three stents. The proximal thoracic aorta was covered in all cases, and the range of coverage was 15-35 cm.
No significant differences between groups were found in the comorbidity profile, presence of risk factors, or dissection morphology. With patients followed for 5 years, differences in outcomes between patients who had undergone TEVAR plus OMT and those who received only OMT began to emerge.
Analysis of these long-term data shows that patients with stable type B aortic dissections who were randomized to receive TEVAR plus OMT showed less aorta-specific mortality (7 vs. 19%, P = .04) and delayed disease progression (27% vs. 46%, P = .04) than did those who received OMT alone. Landmark analysis suggested a benefit of TEVAR for all endpoints between 2 and 5 years, including all-cause mortality (0 vs. 17%, P = .0003).
Both improved survival and less progression over 5 years after TEVAR were associated with stent graft–induced false lumen thrombosis in 91% of cases (P less than .0001). Use of the stent graft resulted in a significant reduction in false lumen diameter (P less than .0001) and significant increase in true lumen diameter (P less than .001). In contrast, a significant increase in aortic diameter was noted in those who received only OMT (P less than .0001).
"In conclusion, endovascular therapy in addition to medical therapy is associated with improved 5-year aortic-specific survival and delayed disease progression. In uncomplicated type B dissection with suitable anatomy, preemptive TEVAR should be considered to improve late outcomes," said Dr. Clough.
Dr. Clough had no disclosures. INSTEAD was sponsored by the Medtronic Bakken Research Center.