BACKGROUND: Atrial secondary mitral valve regurgitation (ASMR) is a distinct anatomical subset of secondary mitral regurgitation (SMR). Evidence of the effect of transcatheter edge-to-edge repair (TEER) on left atrial (LA) anatomy and function, especially reverse remodelling (LARR), is still sparse. METHODS AND RESULTS: We retrospectively evaluated all consecutive patients treated with TEER for mitral regurgitation (MR) in our centre between January 2013 and October 2023. Of the 597 patients with SMR, 103 patients (17.3%) met the inclusion criteria for ASMR. All patients in the ASMR group (mean age 79.4 ± 6.8 years, 71% female) were symptomatic (89% NYHA ≥ III) and had a mean logistic EuroScore of 22.5 ± 12.4%. TEER was successfully performed in all patients, and invasive LA mean pressures decreased intraprocedurally from 17.8 ± 5.7 to 13.1 ± 4.8 mmHg (P <
0.001). At hospital discharge, 94% of patients had mild residual or non/trace MR. At 1YFUP, the prevalence of residual moderate MR was 7% and 1% had severe MR. A significant reduction in LA volume compared with baseline, both at end-systole (151.4 ± 64 vs. 113 ± 64 mL, P <
0.001) and at end-diastole (119.8 ± 56 vs. 91.2 ± 56.9 mL, P <
0.001) could be observed. Seventy per cent of patients had a sustained decrease in NYHA class ≤ II. LARR, defined as LAESV decrease ≥15% at 1YFUP, was documented in 59% of patients. These patients were more likely to have lower post-interventional mitral valve mean pressure gradients (2.2 ± 0.8 mmHg vs. 2.8 ± 1.1 mmHg, P = 0.02) and lower BNP at discharge and at 1 month follow-up [319 (197.8 to 526) vs. 560 (279.3 to 929), P = 0.07, and 287.5 (191.3 to 386.3) vs. 506.5 (223.3 to 935.5), P = 0.06, respectively]. A multivariate logistic regression analysis identified pre-procedural MPG (P = 0.06, OR 0.92, CI 95% 0.85-1.00) and BNP at discharge (P = 0.11, OR 0.99, CI 95% 0.99-1.00) as independent predictors for the occurrence of LARR at 1 year. CONCLUSIONS: Transcatheter mitral valve repair by edge-to-edge therapy represents a safe and effective therapeutic option in symptomatic patients with atrial secondary mitral regurgitation and might have the potential to induce left atrial reverse remodelling.