Percutaneous septal ablation by alcohol-induced septal branch occlusion was introduced as a new treatment option in symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM). Our aim was to evaluate procedural and long-term clinical and echocardiographic outcomes in patients with HOCM treated by alcohol septal ablation (ASA) at our center. This single-center retrospective study included 14 consecutive HOCM patients undergoing percutaneous ASA (66.4 +/- 12.1 years, 71.4% female). At baseline all patients presented persistent symptoms despite optimized medical treatment, left ventricular outflow tract (LVOT) obstruction with a peak gradient > 50 mmHg, systolic anterior motion of the mitral valve, and ventricular septal thickness > or = 15 mm. ASA was considered successful when the LVOT pressure gradient fell to less than 50% of baseline value. All patients had echocardiographic evaluation at baseline, intraprocedure and at follow-up, and a long-term clinical follow-up (25 +/- 38 months) with evaluation of functional class and occurrence of symptoms or cardiovascular events. Percutaneous ASA achieved a 71.4% acute and 85.7% long-term success rate. Peak LVOT gradient decreased from 104 +/- 40 mmHg at baseline to 58 +/- 30 mmHg intraprocedure (p = 0.03) and 35 +/- 26 mmHg at follow-up (p = 0.001); total gradient decrease was 75 +/- 43 mmHg. Ventricular septal thickness and mitral regurgitation also presented significant decreases during follow-up (from 24 +/- 5 mm to 18 +/- 4 mm, p = 0.02, and from grade 2.4 +/- 0.6 to 1.4 +/- 0.5, p < 0.001, respectively). A tendency for long-term improvement in NYHA functional class (from 2.6 +/- 1.1 to 1.8 +/- 1.4, p = 0.09) was observed. Procedural complications occurred in 6.7% of patients; two deaths and one transient ischemic attack occurred in-hospital, but no long-term clinical events were recorded. Percutaneous ASA is an effective treatment for symptomatic patients with HOCM, obtaining a marked decrease in LVOT pressure gradient and symptomatic improvement. Despite the occurrence of a significant number of procedural complications, the favorable long-term outcomes underline the potential of ASA as a percutaneous alternative to surgical myectomy.