P2495Poor cardiorespiratory fitness in adolescence predicts cardiomyopathy risk in mid-life

Abstract

Abstract Background Cardiorespiratory fitness and physical activity have well–known cardio–protective effects. Along with reports on declining levels of physical activity globally, heart failure caused by cardiomyopathy is increasing among young people. Still, it is unknown whether poor fitness in adolescence can be associated with cardiomyopathy in adulthood. Purpose To study a possible link between cardiorespiratory fitness in adolescence and being diagnosed with cardiomyopathy in adulthood. Methods A nationwide register-based prospective cohort study of 1,668,893 young men (mean age 18.3 years, SD 0.7), enlisting for compulsory military service 1969–2005. Body mass index (BMI) and blood pressure were registered at baseline, along with test results for fitness. Values were trichotomized and about 13.5% were classified as having poor cardiorespiratory fitness. Cardiomyopathy diagnoses were identified from the National Hospital Register and Cause of Death Register, during an up to 46-year follow-up, and divided into categories: 1) dilated, 2) hypertrophic, 3) alcohol/drug-induced, and 4) other. Hazard ratios (HR) were calculated with Cox proportional hazards models. Results During follow-up (median 27 years; interquartile interval 19–35 years), 4,477 cases of cardiomyopathy were registered, of which 2,631 (59%) were dilated, 673 (15%) were hypertrophic, and 480 (11%) were alcohol/drug-induced. Poor cardiorespiratory fitness was strongly associated with elevated risk of both dilated (HR 1.59, 95% confidence interval (CI) 1.38–1.83) and alcohol/drug–induced cardiomyopathy (HR 2.32, 95% CI 1.68–3.20), adjusted for BMI, age at conscription, conscription year, test center, and baseline comorbidities (diabetes, hypertension, congenital heart disease). Conclusion The present study shows that poor cardiorespiratory fitness in adolescence may be associated with both dilated and alcohol/drug–induced cardiomyopathy in adulthood. This strengthens the evidence of fitness as a cardio–protective factor, and brings further support to the importance of interventions promoting physical activity already in childhood. Acknowledgement/Funding The Swedish Research Council, The Swedish Heart and Lung Foundation