Ventricular Tachyarrhythmia Associated with Hypertrophic Cardiomyopathy: Incidence, Prognosis, and Relation to Type of Hypertrophy

OBJECTIVE: To assess the incidence, characteristics, and prognosis of ventricular tachyarrhythmia in hypertrophic cardiomyopathy (HCM). PATIENTS: The study consisted of 66 consecutive patients with HCM who were admitted to Niigata University Hospital between 1992 and 2005. Their clinical characteristics and ECG morphology were investigated according to the type of HCM. RESULTS: The type of HCM was asymmetric hypertrophy (ASH) in 34 patients (51%), obstructive HCM (HOCM) in 9 (14%), apical HCM (ApHCM) in 14 (21%), and midventricular obstruction (MVO) in 9 (14%). The cause of admission was ventricular tachyarrhythmia in 25 patients (38%), unexplained syncope in 11 (17%), and heart failure in 30 (45%). Sustained monomorphic ventricular tachycardia (SMVT) occurred in 19 patients and ventricular fibrillation in 6. In the 19 patients with SMVT, 12 had MVO and 3 of these had previous apHCM. Six of the 19 patients with SMVT had ASH, and 3 had abnormal apical wall motion. In 14 patients, the SMVT appeared to originate from the apical aneurysm based on the morphology of the tachycardia. Ventricular tachyarrhythmia recurred in 14 of the 25 patients (56%), and 4 of the 18 patients with an ICD had electrical storm. ASH with abnormal wall motion of the LV apex or MVO was recognized in the 4 patients with electrical storm; they commonly had abnormal Q waves and ST elevation in leads V4-V6. CONCLUSION: Ventricular tachyarrhythmia was responsible for 38% of hospitalizations in HCM, and SMVT occurred in patients with MVO and/or with abnormal wall motion of the LV apex. Electrical storm was more common in patients with ST elevation in precordial leads V4-V6.