Characterising the phenotype and outcomes of cascade-tested relatives of probands with hypertrophic cardiomyopathy

OBJECTIVES: Cascade-tested relatives of individuals with pathogenic genetic variants in sarcomere genes causing hypertrophic cardiomyopathy are recommended. Little is known about the outcomes in cascade-identified relatives. We aimed to characterise the endpoints for these individuals. METHODS: A retrospective cohort case note evaluation of 64 families reviewed by NHS Tayside Clinical Genetics between January 2010 and December 2018 was conducted, identifying 280 patients. The primary endpoint of the study was the composite endpoint of the onset of a repeat major adverse cardiac event (MACE). Analysis of covariance was used to model marginal mean estimates for baseline interventricular size. Cox proportional hazards model was used to depict time to MACEs. RESULTS: Asymmetrical septal hypertrophy fulfilling diagnostic criteria on echocardiography was noted in 35.4% of cascade-tested individuals. Adjusted interventricular septal size for cascade-tested individuals with a positive genotype (13.9 mm; 95% CI (12.1 to 15.8)) was lower than that of probands with a pathogenic variant (22.1 mm; 95% CI (19.7 to 24.4); p