Alcohol septal ablation (ASA, TASH, Sigwart procedure) is a percutaneous, minimally-invasive treatment performed by an interventional cardiologist to relieve symptoms and improve functional status in severely symptomatic patients with hypertrophic cardiomyopathy (HCM) who meet strict clinical, anatomic and physiologic selection criteria. In carefully selected patients, when performed by an experienced interventional cardiologist, the procedure is successful in relieving symptoms in over 90% of patients.