INTRODUCTION: Spontaneous ventricular arrhythmias have been noted to be predictive of sudden death in patients with hypertrophic cardiomyopathy (HCM). Nonsustained ventricular tachycardia occurs in 19-28% of patients with HCM, but spontaneous monomorphic ventricular tachycardia with reproducible initiation with programmed ventricular stimulation is rare. Left ventricular aneurysm without coronary artery disease is a rare phenomenon. The underlying disease is varied but the incidence of HCM in the dilated phase is high. Clinically stable ventricular tachycardia (VT) in these patients is rare: a relation with the presence of midventricular obstruction and apical aneurysm has been proposed.
CASE PRESENTATION: A 50 year old white male with a history of HCM presented about 10 years ago with syncopal VT and class II-III dyspnea. The transthoracic echocardiogram showed asymmetric hypertrophy of the left ventricular septum and a discrete apical aneurysm distal to mid ventricular obstruction; cardiac catheterization showed no coronary disease but visualized discrete apical aneurysm (Fig1). A permanent dual chamber pacemaker (DDD) with short atrioventricular delay and an implantable cardioverter defibrillator (ICD) were implanted at that time.Both patients'symptoms and ventricular arrhythmias were initially controlled with combined antiarrhythmic therapy and pacemaker programming in addition to several antitachypacing (ATP) therapies by the ICD for 10 years. However, the patient experienced recurrence of his VT which became incessant inspite of optimizing his antiarrhythmic medications and reprogramming the ICD. He continued to have frequent ATP therapies and defibrillator cardioversions.An electrophysiological study was performed in attempt to map and ablate the VT. The mapping showed a large but discrete segment of absent or very low voltage electrograms at the apical aneurysm site. Sustained monomorphic VT was consistently induced with program stimulation. Reentry mechanism was confirmed by entrainment criteria. Radiofrequency ablation was unsuccessful. Thereafter the patient was referred for surgery where a large discrete fibrous and trabeculated apical aneurysm harbouring small thrombi was found. Aneurysmectomy with subendocardial resection was performed. Following the surgical procedure all antiarrhythmic therapies were discontinued. The patient had no recurrence of VT and no ICD discharges during two years follow up. He was on metoprolol 25 mg twice a day orally.
DISCUSSIONS: HCM of midventricular type is a rare entity. Although non-sustained VT is common in patients with HCM, sustained monomorphic VT is rare. The major cause of mortality in HCM is sudden death. Clinical sustained monomorphic VT in patients with HCM is uncommon but may be underestimated because of early degeneration into ventricular fibrillation that has been well documented in these patients during electrophysiologic study. Alfonso et al found only two patients with clinical monomorphic sustained VT among 51 consecutive patients with HCM. In both patients, they described echocardiographic and ventriculographic evidence of apical aneurysm, with angiographically normal coronary arteries.
CONCLUSION: Treatment of VT in patients with HCM associated with aneurysm may not be successful with radiofrequency ablation because of inability to isolate completely the scar tissue. In only one case report of HCM with aneurysm was radiofrequency ablation successful in terminating the tachycardia but recurrence is common. Surgical resection of the aneurysm is well tolerated and successful in eliminating VT in the patient so it should be considered as the effective treatment in such rare cases of HCM.
DISCLOSURE: Rabih Touma, None.