Myocardial mechanics explains the time course of benefit for septal ethanol ablation for hypertrophic cardiomyopathy.

We hypothesized that the time course of left ventricular (LV) outflow tract gradient reduction during septal ethanol ablation for patients with symptomatic hypertrophic obstructive cardiomyopathy is related to changes in myocardial mechanics. A total of 21 patients with hypertrophic obstructive cardiomyopathy undergoing septal ethanol ablation were analyzed. LV outflow tract gradient decreased with septal balloon occlusion, further decreased postethanol injection, and partially rebounded at discharge (5-6 days postprocedure). During balloon occlusion longitudinal and circumferential strain significantly decreased in all analyzed segments, significantly improved with alcohol injection only at sites distant to infarction, and normalized at all segments except infarcted ones at discharge. LV twist significantly improved with ethanol injection and remained high at discharge. Myocardial mechanics suggest that the decrease in LV outflow tract gradient during septal ethanol ablation coincides with global LV dysfunction despite only local ischemia during septal balloon occlusion. Global dysfunction is transient and the gradient rebounds when dysfunction is limited to the basal septum.