BackgroundEver since the first description of hypertrophic cardiomyopathy (HCM), the most common genetic cardiac disease, tremendous progress has been made in the evaluation and management of HCM patients, but little attention has been focused on the impact of HCM on societal costs and quality of life (QoL).AimsThis paper describes the study protocol for the AFFECT-HCM study into burden of disease (BoD), which aims to estimate health-related QoL and societal costs in HCM patients and genotype-positive phenotype-negative (G+/P−) relatives during a one-year follow-up study, and relate this to the phenotypical HCM expression.MethodsA total of 400 Dutch HCM patients and 100 G+/P− subjects will be followed for one year in a prospective, multi-centre, prevalence-based BoD study. Societal costs will be measured via a bottom-up approach using the cost questionnaires iMCQ and iPCQ. For QoL, the generic EQ-5D-5L and disease-specific Kansas City Cardiomyopathy Questionnaire will be used. QoL and societal costs will be compared with phenotype-specific HCM characteristics and other determinants to identify factors that influence BoD. Accelerometry will test the correlation between BoD and physical activity.ConclusionThe AFFECT-HCM study will evaluate the BoD in HCM patients and G+/P− subjects to improve the understanding of the societal and economic impact of HCM.