Point/Counterpoint: Is TEVAR required for all Type B aortic dissections?
The INSTEAD trial7 evaluated the management of uncomplicated type B aortic dissection and compared optimum medical therapy (OMT) to OMT with TEVAR. A total of 140 subjects were enrolled at seven European sites with 68 patients enrolled in OMT and 72 in OMT with TEVAR. In patients treated with TEVAR there was 90.6% complete FL thrombosis with a maximum true lumen diameter of 32.6 mm as compared to 22% and 18.7 mm in those treated with medical therapy alone. Furthermore, there was a 12.4% absolute risk reduction in aortic specific mortality and a 19.1% absolute risk reduction in disease progression in patients treated with TEVAR.
It is clear that patients that present with complicated type B aortic dissections mandate intervention with TEVAR and potentially other interventions to alleviate the complications at presentation. INSTEAD demonstrates that elective TEVAR results in favorable aortic remodeling and long-term survival, reinterventions were low, and it prevents late expansion and malperfusion. TEVAR was also associated with improved 5-year aortic-specific survival. TEVAR appears to be beneficial in those patients who present initially with a false lumen diameter of greater than 22 mm and an aortic diameter of greater than 40 mm with a patent false lumen.
References
1. Circ. Cardiovasc. Interv. 2013;4:407-16.
2. J. Vasc. Surg. 2012;55:641-51.
3. J. Vasc. Surg. 2011;54:985-92
4. Ann. Thorac. Surg. 2004;78:1268-73.
5. Ann. Thorac. Surg. 2007;83:1059-66.
6. J. Vasc. Surg. 2009;50:510-17.
7. Circulation 2009;120:2519-28.
Dr. Arko is with the Aortic Institute, Sanger Heart & Vascular Institute, Charlotte, N.C. He reported no relevant conflicts.
No, evidence supports careful choice of patients.
While the role of TEVAR has been proven to treat complications of acute type B dissections,1 its value as a prophylactic treatment in uncomplicated cases remains controversial. Optimal medical treatment (OMT) with strict blood pressure (SBP less than 120 mm Hg) and heart rate control is associated with a low morbidity and mortality, despite the risk of progressive aortic dilation. On the other hand TEVAR can result in early death and significant neurologic complications; other devastating complications of TEVAR include retrograde aortic dissection and access vessel rupture with a high associated mortality.
A meta-analysis of the published literature reported a high technical success of TEVAR for uncomplicated type B dissection and a relatively high conversion rate (20%) for patient treated with OMT, however the results did not identify an advantage for TEVAR with respect to 30-day and 2-year mortality.2
An expert panel review of the world literature also did not find significant data to support use of TEVAR for uncomplicated type B dissection.3 In the only randomized prospective trial to examine the role of TEVAR for uncomplicated type B dissection, the INSTEAD trial randomized 140 patients to OMT vs. OMT and TEVAR.4 The study results also did not support the use of TEVAR for the treatment of uncomplicated type B dissection, there was no survival advantage at 2 years, while TEVAR was associated with a 11.1% overall mortality and 4.3% neurologic complication rate, compared with 4.4% and 1.4% in the OMT group. The initial study did however report improved aortic remodeling at 2 years with TEVAR. The results of INSTEAD have been challenged because critical analysis of the INSTEAD trial has determined that the results were underpowered and that there was a 21% crossover in the OMT group and four patients received TEVAR that should have been excluded.5
Subsequent long-term analysis of the INSTEAD XL data do demonstrate a significant survival benefit and freedom from aortic adverse events in the TEVAR group after the initial 2-year analysis.6 At the 5-year follow up only 27 patients remained without a TEVAR. Fortunately there were no adverse events in the patients that crossed over to TEVAR from the OMT group demonstrating the safety of delayed TEVAR in this group. The high rate of aortic associated adverse events may favor early TEVAR. The INSTEAD XL study did identify a large primary tear (more than 10 mm) and an initial aortic diameter of 40 mm as risk factors to crossover suggesting a more aggressive approach in this subset of patients.
So while the INSTEAD XL trial now supports the use of TEVAR for uncomplicated type B dissections this was a relatively small trial that was underpowered in its initial analysis. Expert review of the world literature still supports medical management in the initial phase of treatment. Obviously in cases of failure of medical management TEVAR provides an effective treatment to restore the true lumen and visceral perfusion with possible sustained remodeling of the false lumen.
