Inappropriate therapy from a defibrillator complicating transcoronary ablation of septal hypertrophy in a patient with hypertrophic obstructive cardiomyopathy.

This case report describes a patient with obstructive hypertrophic cardiomyopathy who received therapy inappropriately from his implanted defibrillator, subsequent to transcoronary alcohol ablation for septal hypertrophy (TASH). Widening of the intracardiac electrogram postablation resulted in "double counting" of the intrinsic ventricular electrogram by the device and inappropriate tachycardia detection.