Counterpoint: challenges and limitations of transcatheter aortic valve implantation for aortic regurgitation.

Transcatheter aortic valve implantation (TAVI) for isolated aortic regurgitation (AR) comprises <1.0% of all TAVI procedures performed in the USA. In this manuscript, we review the challenges, evidence and future directions of TAVI for isolated AR. There are no randomised clinical trials or mid-term data evaluating TAVI for isolated AR, and no commercially available devices are approved for this indication. Challenges in performing TAVI for isolated AR as opposed to aortic stenosis (AS) include: lack of a calcified anchoring zone for valve deployment, large and dynamic size of the aortic annulus and high stroke volume (during systole) and regurgitant volume (during diastole) across the aortic annulus during each cardiac cycle. Observational studies have shown that outcomes of TAVI for AR are worse than outcomes of TAVI for AS. However, newer generation TAVI devices may perform better than older generation devices in patients with AR. Two emerging valves (the JenaValve and the J-Valve) are designed with mechanisms to anchor in a non-calcified annulus, and these valves have shown promise for AR. Data on these devices are limited, and clinical investigation is ongoing. Randomised clinical trials are needed to establish TAVI as a safe and effective treatment for isolated AR.