Abstract 14162: Abnormal Ventricular Conduction Sequence on Magnetocardiography is Useful for Predicting Lethal Arrhythmic Events in Patients with Hypertrophic Cardiomyopathy and Preserved Systolic Function
Background: Identifying the subgroup of individuals at high risk for sudden cardiac death (SCD) remains a challenging issue in hypertrophic cardiomyopathy (HCM). We hypothesized that multi-directional left ventricular (LV) conduction (MDC, Figure) on high-resolution magnetocardiography (MCG) revealed by our preliminary study (AHA 2011) predicts future lethal ventricular arrhythmias in HCM patients.
Methods: In HCM patients (n=106, 74 men) with preserved LV function (%FS>25%) and QRS <120ms, we recorded 64Ch MCGs (Hitachi), yielding 2-D mapping. Sustained ventricular tachycardia (sVT) or fibrillation (VF) was documented in 10, and 20 experienced unexplained syncope. Other 26 were mildly symptomatic, and 50 were asymptomatic. On QRS mapping, we measured LV conduction time (LVCT, an interval from QRS onset to the instance when LV leftward current disappears) and defined the presence of MDC (multi-directional currents observed simultaneously, magnitude of extra-current > 25% main current). Healthy 25 volunteers served as Controls. Lethal arrhythmic events were investigated.
Results: LVCT in HCM was prolonged compared with Controls (66 ± 14 vs. 51 ± 5ms, p<0.001). MDC was found in 30 patients (28%, Group-A), but not in 76 patients (Group-B). LVCT was comparable between the groups. During the follow-up (834 ± 624 days), 11 events occurred (1 SCD, 5 sustained VT, and 5 appropriate ICD discharge). Kaplan-Meier analysis showed that arrhythmic events more frequently occurred in Group-A (7/30, 23%) than in Group-B (4/76, 5%, p=0.003). Multivariate analysis revealed MDC as the only independent predictor (p=0.017); other classical risk factors (wall thickness≥30mm, history of sVT/VF, family history of SCD, unexplained syncope) did not reach statistical significance.
Conclusion: High-resolution MCG has a potential to disclose abnormal LV intraventricular conduction that predicts future lethal arrhythmic events in HCM patients with preserved LV function.
- © 2012 by American Heart Association, Inc.