Transcatheter aortic valve implantation effects on pre-existing mitral regurgitation: improvement timing, predictive factors and mortality impact

Introduction Transcatheter aortic valve implantation (TAVI) is a proven effective treatment for severe aortic valve disease in inoperable patients. In those patients, concurrent mitral regurgitation (MR) remains common. Although MR improvement following TAVI is expected, the timeframe, predictors, and potential clinical implications remain unclear. Purpose To evaluate changes in MR severity post-TAVI at pre-defined timepoints, determine potential predictive factors and assess the impact on all-cause mortality. Methods A registry of consecutive patients (n=924) undergoing successful TAVI at a tertiary cardiac centre between 2020 and 2024 was retrospectively reviewed to identify those with pre-existing MR. MR severity was assessed by BSE-accredited practitioners using transthoracic echocardiography and a multimetric semi-quantitative approach, categorised as none, mild, moderate, or severe. Data was analysed at baseline, immediately post-TAVI, and at 3-6 months follow-up. MR severity changes were analysed using paired non-parametric testing while univariable comparative statistics was used to assess MR improvement predictors and mortality impact. Results 124 patients were included with baseline MR - mild in 16.3%(n=20), moderate in 67.4%(n=84) and severe in 16.3%(n=20). Mean age was 81.2±8.0 years, 59 were male(47.7%) and 65 female(52.4%). Self-expanding prosthesis was used in 45%(n=56) and balloon-expandable in 55%(n=68). Post-procedural echocardiographic data was available for 120 patients (96.8%) immediately post-TAVI and 83 patients (66.9%) at follow-up. MR improved by at least one grade in 45% (n=54) (p<0.05) immediately post-TAVI and in 71.1% (n=59) (p<0.05) at outpatient follow-up. Where MR severity remained static immediately post-TAVI, a delayed improvement was noted at outpatient echocardiography in 26.6%. Immediately post-TAVI, female gender was significantly correlated with MR improvement (54.0% vs 35.1%; Fisher's exact p=0.045). MR severity changes were independent of operator(p=0.711), valve platform(p=0.133) and size(p=0.698) used, MR aetiology(p=0.672), baseline tricuspid regurgitation (TR) severity (p=0.801) or LV function (p=0.738). At outpatient follow-up, there was no baseline or procedural variables significantly associated with MR improvement (all p>0.05). This was also independent of TAVI indication and baseline moderate or severe AR at both timepoints (p=0.223 and p=0.214). We have observed, however, a non-significant trend towards higher late MR improvement with increasing baseline TR severity (linear-by-linear association p=0.072). Mortality was lower among patients with MR improvement(death OR 0.37, 95% CI 0.15–0.94; p=0.036). Conclusion Baseline MR severity significantly improved following TAVI, both immediately and at outpatient follow-up. Female sex predicted early improvement, while no predictors of late improvement were identified. MR improvement was associated with reduced all-cause mortality.