Nonsurgical septal reduction therapy (NSRT) with ethanol improves clinical and hemodynamic parameters in patients with symptomatic hypertrophic obstructive cardiomyopathy. The purpose of this study was to examine the impact of infarct size induced by ethanol injection on clinical and echocardiographic outcome after the procedure.

The first 261 consecutive patients were included. The mean age was 51 ± 6 years, and 127 patients were women. The mean creatine kinase (CK) after NSRT was 1411 ± 653 units. Men had larger infarcts than women (P = .0028). Injecting ethanol as a bolus (P < .001), injecting >1 septal branch (P < .001), or injecting >3 cc of ethanol per septal branch (P < .001) were all determinants of infarct size. When the patients were divided into 4 groups according to peak CK, the New York Heart Association dyspnea score after NRST, the septal thickness, and left ventricular outflow tract gradient were more significantly reduced in patients with peak CK >1000 U/dL compared to those with peak CK <1000 U/dL. Patients with peak CK >1500 U/dL had a significant drop in left ventricular ejection fraction at 6 weeks (70 ± 6 vs 63 ± 6, P = .035).

An average size infarct (peak CK 1000–1500 U/dL) seems to lead to the optimal outcome after NSRT.