Functional Recovery After Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy—When Measured Success Does Not Equal Complete Recovery

Alcohol septal ablation (ASA) is an established septal reduction therapy for symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM). Although successful treatment is traditionally defined by a reduction in left ventricular outflow tract (LVOT) obstruction and improvement in symptoms, these parameters do not necessarily indicate complete functional recovery. Persistent exercise intolerance may occur despite an apparently successful intervention, reflecting the complex pathophysiology of HCM. This review explores the mechanisms underlying incomplete functional recovery after ASA and evaluates contemporary approaches to objectively assess treatment response. Functional capacity after ASA is determined by multiple interacting factors, including residual or recurrent LVOT obstruction, abnormal mitral and papillary muscle anatomy, persistent diastolic dysfunction, myocardial fibrosis, valvular disease, pulmonary hypertension, and coronary microvascular dysfunction. Age, deconditioning, pulmonary disease, anemia, musculoskeletal limitations, and other comorbidities may independently contribute to exercise intolerance. Conventional assessment based on New York Heart Association functional class and resting echocardiography may therefore underestimate persistent physiological impairment. Cardiopulmonary exercise testing (CPET) provides a comprehensive assessment of exercise capacity by integrating cardiovascular, pulmonary, and metabolic responses. Exercise echocardiography, cardiac magnetic resonance, pulmonary function testing, and, in selected patients, invasive exercise hemodynamics provide complementary information. Emerging strategies including multimodality imaging, pharmacological therapy, individualized rehabilitation, and wearable activity monitoring may further improve assessment and long-term recovery. Conclusions: Successful reduction in LVOT obstruction after ASA should not be considered synonymous with complete functional recovery. A multimodality, physiology-oriented approach, with CPET as a central objective tool, may better identify residual limitations and guide individualized management. Future studies should focus on physiological rather than purely anatomical endpoints and determine whether patient selection, procedural precision, and phenotype-guided rehabilitation can improve functional recovery after ASA.