Background: Mitral regurgitation (MR) commonly coexists with aortic stenosis (AS) and is a potential risk factor influencing outcomes following transcatheter aortic valve replacement (TAVR). This meta-analysis aimed to evaluate the mean changes in key echocardiographic parameters before and after TAVR and to compare these changes between patients with moderate-to-severe MR (MR ≥ 2) and those with none-to-mild MR (MR < 2).

Methods: A comprehensive literature search was conducted using six electronic databases. We included studies that evaluated patients undergoing TAVR, classified them based on baseline MR grade ≥ 2 (moderate/severe MR) or MR grade < 2 (none/mild MR), and reported the mean difference (MD) in echocardiographic parameters before and after TAVR in both groups. The primary outcomes included changes in ejection fraction (EF), LV end-diastolic volume (LVEDV) index, LV end-systolic volume (LVESV) index, LV end-diastolic diameter (LVEDD), LV end-systolic diameter (LVESD), aortic valve area (AVA), and the mean aortic gradient. Pooled MDs were analyzed using a random-effects model.

Results: Thirteen studies with 7163 patients were included, of which 2376 had an MR ≥ 2. The MR < 2 and MR ≥ 2 groups experienced significant improvements in AVA and reductions in mean aortic gradient, LVEDV index, LVESV index, LVEDD, and LVESD. Compared to MR < 2 patients, those with MR ≥ 2 exhibited significantly greater improvements in EF (MD = 2.03; 95% CI: 0.81, 3.24), LVEDV index (MD = -5.55; 95% CI: -7.85, -3.26), LVESV index (MD = -5.43; 95% CI: -7.28, -3.58), LVESD (MD = -2.23; 95% CI: -3.71, -0.26), and mean aortic gradient (MD = 1.43; 95% CI: 0.79, 2.07). However, the changes in LVEDD and AVA were not significantly different between the groups.

Conclusions: These findings suggest that patients with moderate-to-severe baseline MR before TAVR showed greater pronounced improvements in specific echocardiographic parameters related to LV function and geometry, particularly in LVEF, LVEDV index, LVESV index, and LVESD, compared to those with none-to-mild MR. Future studies should focus on stratifying outcomes according to MR etiology and using advanced imaging techniques to delineate better the mechanisms underlying these improvements.