Impact of mitral regurgitation aetiology on the outcomes of transcatheter aortic valve implantation.

Background: Concomitant moderate/severe mitral regurgitation (MR) is observed in 17-35% of patients undergoing transcatheter aortic valve implantation (TAVI) and contributes to a worse prognosis. Studies analysing outcomes in patients undergoing TAVI with different MR aetiologies, including atrial functional MR (aFMR), are lacking.
Aims: We aimed to analyse outcomes and changes in MR severity in patients with aFMR, ventricular functional (vFMR) and primary mitral regurgitation (PMR) following TAVI.
Methods: We analysed all consecutive patients with at least moderate MR undergoing TAVI between January 2013 and December 2020 at the Munich University Hospital. Characterisation of MR aetiology was performed by detailed individual echocardiographic assessment. Three-year mortality, changes in MR severity and New York Heart Association (NYHA) Functional Class at follow-up were assessed.
Results: Out of 3,474 patients undergoing TAVI, 631 patients showed MR ≥2+ (172 with aFMR, 296 with vFMR, 163 with PMR). Procedural characteristics and endpoints were comparable between groups. The rate of MR improvement was 80.2% in aFMR patients, which was significantly higher compared to both other groups (vFMR: 69.4%; p=0.03; PMR: 40.8%; p<0.001). The estimated 3-year survival rates did not differ between aetiologies (p=0.57). However, MR persistence at follow-up was associated with increased mortality (hazard ratio 1.49, 95% confidence interval: 1.04-2.11; p=0.027), mainly driven by the PMR subgroup of patients. NYHA Class improved significantly in all groups. In patients with baseline MR ≥3+, the PMR aetiology was associated with the lowest MR improvement, the lowest survival rates and least symptomatic improvement.
Conclusions: TAVI reduces MR severity and symptoms in patients with aFMR, vFMR and less-pronounced PMR. The presence of aFMR was associated with the greatest MR severity improvement.