ELECTROCARDIOGRAPHIC CHANGES AFTER ALCOHOL SEPTAL ABLATION IN HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY

Objective-To report acute and mid-term electrocardiographic changes in patients with hypertrophic obstructive cardiomyopathy (HOCM) after al cohol ablation of the first large septal branch of the left anterior d escending coronary artery; and to relate electrocardiographic data wit h the left ventricular outflow tract pressure gradients. Patients-Nine consecutive symptomatic patients with HOCM (mean (SD) age 45 (12) yea rs). Methods-Analysis of baseline and postprocedure ECGs and 24 hour a mbulatory monitoring (up to six months). ECG data were related to left ventricular outflow tract pressure gradients. Results-One patient dev eloped complete atrioventricular block requiring permanent pacing. The PR interval was significantly prolonged up to third month after ablat ion. Immediately after the procedure all patients developed right bund le branch block. At the sixth month of follow up, right bundle branch block was present in four patients. New anterior ST elevation develope d immediately after ablation in five of the nine patients, and new Q w aves in four. The QRS duration was significantly prolonged immediately after ablation and during follow up. There was significant but transi ent prolongation of QT-mean and QTc-mean intervals. QT dispersion, QTc dispersion, and JTc-mean interval were not affected. JT and JTc dispe rsions were transiently prolonged. No serious ventricular arrhythmias were recorded during Holter monitoring, either before or after the pro cedure. There were no significant correlations between the left ventri cular outflow tract pressure gradient and QTc, QT-d, QTc-d, JTc, JT-d, JTc-d, or QRS duration before and after ablation. Conclusions-Alcohol septal ablation for HOCM induces significant changes in the resting E CG in most patients, despite the occlusion of a relatively small arter y. The changes include new Q waves, new bundle branch block, transient anterior ST segment elevation, atrioventricular block, and transient prolongation of QT interval.