Abstract 14030: Hypertophic Cardiomyopathy in the Young: Patterns and Distribution of Hypertrophy
Background Patterns and distribution of hypertrophy in hypertrophic cardiomyopathy (HCM) has been well categorized in the adult population but not systematically described in children and teenagers. We used CMR to characterize the hypertrophy patterns of young patients with HCM and corresponding phenotypic-genotypic relationships.
Methods We undertook a retrospective analysis of 42 children (33 male: 9 female) diagnosed with HCM who had undergone CMR between August 1999 to Feb 2011. Left ventricular volumes, mass and systolic function were measured. An assessment of the pattern of hypertrophy, presence of systolic anterior motion (SAM), degree of left ventricular outflow tract obstruction (LVOTO) and delayed enhancement (DE) was made from the images obtained and compared with echocardiograms performed at close chronological proximity.
Results The mean age of the group was 12.7 years standard deviation (SD) +/- 3.3 years. Mean left ventricular mass index (LVMi) was 111.3+/-38.1g/m2. 31 of the 42 individuals underwent genetic testing and 26 were noted to have a HCM producing gene. 13 tested positive for genetic defects on the myosin binding protein C gene (MYHBPC3) and 10 for the beta-myosin heavy chain gene (MYH7). Figure 1 shows the incidence of hypertophy for the 2 main genetic defects. Concentric hypertrophy was present only in patients with the MYHBPC3 defect. 17 individuals were noted to have SAM, 19 had LVOTO (severe in 10). 7 individuals had DE, 5 of whom had an elevated LVMi of over 130.3 g/m2 (> 73rd percentile). 2 of the 7 with DE had a documented episode of ventricular fibrillation (VF), as compared to 0 out of 35 DE negative patients.
Conclusion The patterns of hypertrophy in childhood HCM vary with the underlying genetic defects. DE though less prevalent than in adults, is related to an increased LVMi and appears to be associated with an increased high risk of VF.
- © 2011 by American Heart Association, Inc.