Exercise related ventricular arrhythmias are related to cardiac fibrosis in hypertrophic cardiomyopathy mutation carriers

Abstract

AIMS: Hypertrophic cardiomyopathy (HCM) is a frequent cause of sudden cardiac death (SCD) due to exercise-related ventricular arrhythmias (ERVA); however the pathological substrate is uncertain. The aim was to determine the prevalence of ERVA and their relation with fibrosis as determined by cardiac magnetic resonance imaging (CMR) in carriers of an HCM causing mutation. METHODS: We studied the prevalence and origin of ERVA and related these with fibrosis on CMR in a population of 31 HCM mutation carriers. RESULTS: ERVA occurred in seven patients (23%) who all showed evidence of fibrosis (100% ERVA(+) vs. 58% ERVA(-), p = 0.04). No ventricular tachycardia or ventricular fibrillation occurred. In patients with ERVA, the extent of fibrosis was significantly larger (8 ± 4% vs. 3 ± 4%, p = 0.02). ERVA originated from areas with a high extent of fibrosis or regions directly adjacent to these areas. CONCLUSIONS: ERVA in HCM mutation carriers arose from the area of fibrosis detected by CMR; ERVA seems closely related to cardiac fibrosis. Fibrosis as detected by CMR should be evaluated as an additional risk factor to further delineate risk of SCD in carriers of an HCM causing mutation.

Fig. 1

Analysis method to determine the origin of ventricular arrhythmias. Localisation within the left ventricle: according to the AHA 17 segment model of the left ventricle [13]. LBBB left bundle branch block, etc. Neg negative, Pos positive, RBBB right bundle branch block, RV right ventricle

Fig. 2

Example of exercise related arrhythmias and fibrosis in one patient. Late gadolinium enhanced (LGE) short axis image (a) showing fibrosis in the basal anteroseptal segment (arrow). In this patient, a ventricular premature beat originated from the corresponding segment or nearby this segment in the right ventricular outflow tract (b)