Aborted Sudden Cardiac Death in a Pediatric Patient with Hypertrophic Cardiomyopathy and a Novel MYH7 Mutation

Abstract

A 14-year-old boy with hypertrophic cardiomyopathy experienced ventricular fibrillation while running in his schoolyard. He was resuscitated and admitted to our hospital. Delayed enhancement cardiac magnetic resonance imaging revealed asymmetric ventricular septal hypertrophy and delayed enhancement of the ventricular septum. Monomorphic ventricular tachycardia (VT) was induced by double ventricular extrastimuli. During electroanatomical mapping, a low voltage area was found in the right ventricle, but none was found in the left ventricular endocardium. Pace-mapping from the anterior right ventricular outflow tract, i.e., the low voltage area, revealed delayed potentials, and pacing at this site generated an 85% morphological match to the induced VT. Endomyocardial biopsy of the right ventricular septum revealed differences in myocyte size and myocardial disarray, along with moderate interstitial fibrosis. A cardioverter defibrillator (ICD) was implanted. Genetic testing identified a novel heterozygous missense mutation in the cardiac myosin heavy chain gene.