By Michael H. Crawford, MD, Editor

SYNOPSIS: Investigators assessed the Society of Thoracic Surgeons/American College of Cardiology transcatheter aortic valve replacement (TAVR) data, with a focus on the use of newer TAVR devices in patients with bicuspid aortic valve vs. tricuspid aortic valves. They found the outcomes post-procedure and for one year are not significantly different between the two types of native valve anatomy.

SOURCE: Halim SA, Edwards FH, Dai D, et al. Outcomes of transcatheter aortic valve replacement in patients with bicuspid aortic valve disease: A report from the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry. Circulation 2020;141:1071-1079.

Early reports of transcatheter aortic valve replacement (TAVR) in patients with bicuspid aortic valves (BAV) showed reduced successful device deployment, a higher incidence of paravalvular regurgitation, and more strokes. This resulted in a lack of Food and Drug Administration approval for this use of TAVR. More recent data about third-generation devices have shown much better results. Halim et al analyzed the Society of Thoracic Surgeons (STS)/American College of Cardiology (ACC) Transcatheter Valve Therapy Registry (TVTR) to evaluate TAVR outcomes in patients with BAV vs. tricuspid valves (TrAV). The TVT is a compulsory database of all commercial TAVR in the United States.

For this analysis, TAVRs performed between late 2011 and late 2018 were included. The authors excluded aborted procedures, previous AV replacement, and other valve morphologies (e.g., unicuspid). Valve prostheses were stratified as early or current (SAPIEN 3 or Evolut R). Several procedural and post-procedural outcomes in hospital, at 30 days and one year, were assessed.

In 593 sites, 170,959 patients met the inclusion criteria. AV morphology was assessed by CT scans in 75%, transesophageal echo in 13%, and transthoracic echo in 12%. BAV was discovered in 5,412 patients who were significantly younger compared to TrAV patients (74 years vs. 82 years; P < 0.001). In 81% of patients, current-generation prosthetic valves were used. Their insertion increased the frequency of successful valve deployment (96.3% vs. 93.5%; P = 0.001). Also, newer valves exhibited less 2+ paravalvular leak (2.7% vs. 14%; P < 0.001).

There was no significant difference in BAV device success compared to TrAV (96.3% vs. 97.4%; P = 0.07), but there was slightly more moderate to severe aortic regurgitation with BAVs (2.7% vs. 2.1%; P < 0.001). In the Medicare subgroup, the adjusted one-year mortality rate was lower in the BAV group (hazard ratio [HR], 0.88; 95% confidence interval [CI], 0.78-0.99), but there was no difference in stroke (HR, 1.14; 95% CI, 0.94-1.39).

The authors concluded procedural, post-procedural and one year outcomes with current TAVR prostheses were comparable in BAV and TrAV.

COMMENTARY

This study is a potential gamechanger, especially for younger patients with BAV. Current guidelines recommend a mechanical prosthesis because of its superior longevity, but it would require near lifelong warfarin therapy, on which many active young patients are not keen. Now, suppose a patient between age 35 and 40 years with symptomatic severe aortic stenosis or regurgitation could undergo TAVR. By the time this TAVR failed, perhaps this patient could be older than age 50 years and could receive a surgically placed bioprosthetic valve. There now are many options for avoiding warfarin.

The results of this large retrospective, observational registry study of TAVR for BAV are excellent and not clinically different than the results with TrAV. The in-hospital rates of major complications were low: death (2%), stroke (2%), and bleeding (6%). This study confirms the experience in smaller single-center studies of BAV patients. The major trials that permitted commercialization of TAVR all excluded patients with BAV. Even the new trials of TAVR in low-risk patients are excluding BAV patients. Thus, this registry study is important.

There were limitations. There was no external blinded adjudication of valve morphology, and only 75% of patients underwent CT angiography. Also, there was no breakdown by BAV subtypes. In 12% of subjects, the post-procedure echo was missing. In addition, the new Evolut PRO, released in 2017, was not included.

This field is a moving target, as new TAVR devices are arriving rapidly. This study is a start, as mean STS predicted risk of mortality was 3.8% in the BAV patients, which was lower than the 5.6% observed in older TrAV patients (P < 0.001). Expect more liberalization of TAVR use going forward, especially as more data on low-risk patients arrive.