Ventricular tachycardia in mid-ventricular obstructive hypertrophy: electrophysiological and pathological findings, and optimal surgical procedure.

backgroundPatients with mid-ventricular obstructive hypertrophy (MVOH) are frequently complicated with refractory ventricular tachycardia (VT) and at risk of sudden death. However, the mechanism of VT has not been examined, and the optimal therapy has not yet been determined.

methodsPreoperative and intraoperative electrophysiological and pathological findings were examined in six patients who underwent surgery for refractory VT associated with MVOH. Four patients had undergone unsuccessful catheter ablation and four had a defibrillator implanted prior to surgery. Endocardial resection of the left ventricular (LV) apical aneurysm was performed following aneurysm resection in five patients and circumferential endocardial cryothermia was performed at the hypertrophied myocardium in all six patients.

resultsFractionated or isolated late electrograms were recorded at the distal LV chamber, and monomorphic VT was induced in preoperative electrophysiological study in all patients. Intraoperative electrophysiological study was performed with electro-anatomical mapping in three patients, however, a thorough examination of clinical VT was completed only in one patient. There was no surgical or late mortality. During the median follow-up period of 72 months, no patients exhibited a recurrence of VT, except in one who developed preoperatively non-documented VT. Pathological analysis of the resected aneurysms revealed cicatricial fibrosis with a patchy distribution of residual myocardium.

conclusionsVT associated with MVOH appears to result from scar-related reentry in the distal LV aneurysm. Extensive endocardial resection of the LV apical aneurysm with circumferential cryothermia at the hypertrophied myocardium may be an effective strategy for eliminating this refractory and life-threatening VT.