Distinguishing left ventricular hypertrophy from hypertrophic cardiomyopathy in adolescents - a longitudinal observation study

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): MF: The South-Eastern Norway Regional Health Authority [grant number 2017207]. KHH, MKS: Norwegian Research Council [grant number 309762 ProCardio]. Background Distinguishing athlete´s heart from hypertrophic cardiomyopathy (HCM) can be challenging. There is a lack of data describing physiological and pathological remodelling in adolescents. Purpose The purpose of this study was to compare development of left ventricular (LV) hypertrophy in adolescent athletes to HCM genotype positive adolescents. Methods Athletes and age- and sex-matched HCM genotype positive adolescents underwent echocardiography at baseline and at follow-up, minimum two years later. Echocardiographic parameters were evaluated by pediatric reference values (Z-scores). LV hypertrophy was defined as Z-score >2 for intraventricular septum diameter (IVSd) or posterior wall thickness (LVPWd). Results Seventy-six athletes were compared to 63 (1 proband, 62 family members) HCM genotype positive adolescents (37% vs 44% female, p = 0.36, mean age baseline 12.1±0.2 vs 12.4±1.4 years, p = 0.10). Mean follow-up-time was alike by protocol (3.1±0.2 vs 3.2±1.3 years, p = 0.59). LV hypertrophy was found in a similar proportion of athletes and HCM genotype positive adolescents (28% vs 30% at baseline, p = 0.75, 30% vs 32% at follow-up, p = 0.80). Compared with athletes, interventricular septum was thicker in HCM genotype positive adolescents at baseline (Z IVSd 1.4±0.9 vs 2.7±5.2, p = 0.03). Left ventricular volumes were greater in athletes (Z LVEDV 1.0±0.6 vs −0.1±0.9, p<0.001). Septum thickness increased only in HCM genotype positive adolescents (Z IVSd progression rate −0.17(SE0.05), p = 0.001 vs 0.54(SE0.16), p = 0.001, p for interaction <0.001). There was no difference in LVPWd (0.6±1.3 vs 0.8±0.8, p = 0.13). Conclusions LV hypertrophy was observed in nearly 1/3 of both athletes and HCM genotype positive adolescents in the first longitudinal study comparing these populations. We found a significant difference in progression of LV hypertrophy, with increasing septum thickness only in the HCM genotype positive adolescents. These findings highlight the importance of repeated examinations to distinguish physiological from pathological remodelling.