A nomogram for predicting residual mitral regurgitation in patients with obstructive hypertrohpic cardiomyopathy undergoing transapical beating-heart septal myecotmy

Abstract OBJECTIVES Residual mitral regurgitation (MR) after septal myectomy increases the risk of further mitral interventions. This study aimed to identify predictors of residual MR (grade ≥ 2+) following transapical beating-heart septal myectomy (TA-BSM) in hypertrophic obstructive cardiomyopathy (HOCM) patients and to develop a predictive nomogram. METHODS We prospectively enrolled 200 HOCM patients undergoing TA-BSM from April 2023 to March 2024, all with resting or provoked left ventricular outflow tract gradient ≥ 50 mmHg and MR ≥ 2+. Preoperative clinical and echocardiographic MV parameters were analyzed. Predictors were identified via univariate and multivariate logistic regression. A nomogram was constructed and evaluated for discrimination, calibration, and clinical utility. RESULTS Before discharge, 128 (64%) patients had no or mild residual MR, 65 (32.5%) moderate, and 7 (3.5%) moderate-to-severe MR. Independent predictors included atrial fibrillation, leaflet thickening ≥ 5 mm, annular calcification, annular anterior–posterior diameter, and annular height. The nomogram demonstrated good discrimination (AUC 0.879; 95% CI 0.817–0.940), with favorable calibration and clinical utility. CONCLUSIONS Atrial fibrillation, leaflet thickening, annular calcification, annular anterior-posterior diameter, and annular height are independent predictors of residual MR after TA-BSM. The nomogram demonstrated robust predictive performance following internal validation.