Mitral Valve Abnormalities as Predictors of Procedural Success in Alcohol Septal Ablation: A Pilot Study

Background/Objectives: Alcohol septal ablation (ASA) is an established interventional therapy for patients with obstructive hypertrophic cardiomyopathy (OHCM) who remain symptomatic despite optimal medical treatment. Nevertheless, 10-20% of patients fail to achieve a satisfactory hemodynamic or clinical response, highlighting the need for improved patient selection. Given that mitral valve (MV) morphology plays a central role in left ventricular outflow tract (LVOT) obstruction, we aimed to evaluate the impact of MV anatomical parameters on ASA outcomes. Methods: We retrospectively analyzed 38 OHCM patients who underwent ASA and had complete echocardiographic data before and at 6-month follow-up. Patients were stratified into responders (n = 32, defined as >50% reduction in LVOT pressure gradient and/or residual LVOT gradient < 50 mmHg) and non-responders (n = 6, <50% reduction or persistent gradient ≥ 50 mmHg), consistent with criteria used in previous ASA outcome studies. MV parameters-including redundant anterior mitral leaflet (AML) length, posterior mitral leaflet (PML) projection, and anterior displacement of the coaptation point (AML/PML projection ratio)-were compared between groups. Results: Non-responders demonstrated significantly greater AML redundancy (13.16 ± 1.72 vs. 9.96 ± 1.99 mm, p < 0.001), larger PML projection (18.5 ± 3.78 vs. 13.65 ± 3.8 mm, p = 0.006), and lower AML/PML projection ratio (0.80 ± 0.15 vs. 1.34 ± 0.45, p = 0.007). These parameters were associated with reduced post-procedural LVOT gradient reduction in univariate logistic regression (p = 0.01, p = 0.027, p = 0.015, respectively). Multivariate modeling was not pursued due to collinearity among MV parameters and the limited number of non-responder events, which precluded robust adjustment. Conclusions: Mitral valve morphological features-particularly redundant AML, greater PML projection, and anterior displacement of the coaptation point-were associated with suboptimal ASA outcomes in univariate analysis. These data emphasize the need for comprehensive MV imaging in pre-procedural assessment. Integrating MV morphology into current selection algorithms may refine ASA patient selection and improve long-term success rates.