Background—Left ventricular outflow tract (LVOT) obstruction is frequently responsible for symptoms in hypertrophic obstructive cardiomyopathy (HOCM). Medical therapy is often not sufficient to control these symptoms, and surgical myotomy-myomectomy is required.

Methods and Results—We enrolled 33 symptomatic patients with HOCM and obstruction (≥40 mm Hg gradient at rest or ≥60 mm Hg dobutamine-provoked). By contrast echocardiography, the bulging septum was localized and infarcted by injection of 2 to 5 mL of absolute ethanol into the septal artery(ies) supplying the hypertrophied area. Baseline echocardiograms with Doppler, myocardial perfusion tomograms, and treadmill exercise or pharmacological testing were compared with those at 6 weeks and 6 months. The mean rise in creatine kinase was 1964±796 U. All patients experienced symptomatic relief; NYHA class decreased from 3.0±0.5 to 0.9±0.6 (P<0.001). Exercise time increased from 286±193 to 421±181 seconds (P=0.03). The resting and dobutamine-provoked gradient decreased from 49±33 and 96±34 mm Hg to 9±19 (P<0.001) and 24±31 mm Hg (P<0.001), respectively. Echocardiograms repeated at 6 weeks after the procedure showed a 28% reduction in septal thickness and 17% reduction in left ventricular mass. Myocardial perfusion imaging showed a “septal amputation pattern,” with scarring in the upper and middle septal areas. Complete heart block developed in 11 patients, who then required permanent pacemaker implantation.

Conclusions—Echocardiography-guided ethanol septal reduction in patients with HOCM is a safe, minimally invasive procedure that provides symptomatic relief with improved hemodynamic and left ventricular parameters.