While it was once considered an exclusion criterion in pivotal trials, transcatheter aortic valve replacement (TAVR) turns out to be a good option for patients with a bicuspid aortic valve (AV). With current-generation devices, procedural, postprocedural, and 1-year outcomes are all comparable following TAVR for bicuspid AV versus tricuspid AV disease.
The results are based on a large analysis of data from the Society of Thoracic Surgeons (STS)/American College of Cardiology Transcatheter Valve Therapy (TVT) Registry. After promising data from small studies, often single-center experiences, Sharif Halim, MD, MHS, from the Duke Clinical Research Institute, and colleagues evaluated 5,412 TAVR procedures performed in bicuspid aortic valve patients, including 3,705 with current-generation devices.
Early on, TAVR in this setting was associated with perivalvular regurgitation. Consequently, bicuspid patients comprised only 3.2% of all TAVR patients in the TVT Registry. Still, with current-generation TAVR valves (the Edwards Lifesciences Sapien 3 and Medtronic Evolut R), the incidence of device success was only slightly lower for bicuspid than for tricuspid AV patients (96.3% vs. 97.4%; p < 0.001), with residual 2+ aortic insufficiency slightly higher for bicuspid than for tricuspid AV patients (2.7% vs. 2.1%; p = 0.006).
Nevertheless, there was no significant difference in the adjusted 1-year hazard of stroke in patients with bicuspid versus tricuspid valves. The adjusted 1-year hazard of mortality was lower among bicuspid AV patients (hazard ratio: 0.88; 95% confidence interval: 0.78 to 0.99). That is not surprising given that patients with bicuspid AV were significantly younger (74 vs. 82 years; p < 0.001), with a lower STS Predicted Risk of Mortality (3.8% vs. 5.6%; p < 0.001) and a lower prevalence of atrial fibrillation (29.5% vs. 39%; p < 0.001) than tricuspid valve patients.
The choice of device did seem to matter: balloon-expandable valves were associated with a lower risk of significant paravalvular leak in bicuspid AV patients than current-generation self-expanding valves.
What They Were Built to Do
Overall, today’s TAVR devices simply seem to work a lot better than the original transcatheter valves. This makes sense because the newer-generation devices were designed to reduce paravalvular leaks through the use of sealing skirts and facilitated repositioning.
Based on the TVT Registry data, the advance in design has made a difference: the incidence of moderate or greater aortic insufficiency has improved substantially in recent years, from 14.0% with early devices versus 2.7% (p < 0.001) with current-generation devices.
Despite the positive results from this study, there are certainly unique anatomic considerations in patients with bicuspid AV: patients with bicuspid AV tend to have larger aortic annuluses with asymmetric leaflet calcification. Also, bicuspid AV syndrome is associated with ascending aortic dilatation, which may impact longer-term TAVR outcomes. Given these anatomic differences, TAVR patients with bicuspid AV have the potential for worse outcomes.
Improvements in valve function and performance will allow TAVR to be studied further in lower-risk patients where there is a higher prevalence of bicuspid AV. However, it should be noted that a pair of studies in low-risk patients undergoing TAVR for aortic stenosis (PARTNER 3 and the Evolut Low Risk trial) both exclude patients with bicuspid AV.
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 Feb 26 [Online before print]. https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.119.040333