Outcomes of Contemporary Family Screening in Hypertrophic Cardiomyopathy.

Background: Contemporary hypertrophic cardiomyopathy (HCM) family screening includes clinical evaluation and genetic testing (GT). This screening strategy requires the identification of a pathogenic mutation in the proband. Our aim was to examine the results of this HCM screening strategy.
Methods: Between 1985 and 2016, 777 relatives of 209 probands were assessed in the context of HCM screening. Genotype-positive (G+) relatives and relatives without genetic testing (GT) underwent repeated clinical evaluations. In genotype-negative (G-) relatives mortality was assessed during follow-up.
Results: A pathogenic mutation was identified in 72% of probands. After counseling, GT was performed in 620 (80%) relatives: 264 (43%) were G+ (age 41±18 y) and 356 (57%) were G- (age 48±17 y). At first screening, HCM was diagnosed in 98 (37%) G+ relatives and 28 (17%) relatives without GT ( p <0.001). During 9 years follow-up of relatives diagnosed with HCM, 8 (6%) underwent septal reduction therapy, 16 (16%) received primary prevention ICDs, and cardiac mortality was 0.3%/year. During 7 years follow-up of relatives without HCM, 29 (16%) developed HCM. Survival at 5/10 years was 99%/95% in G+ relatives, 97%/94% in G- relatives ( p =0.8), and 100%/100% in relatives without GT.
Conclusions: HCM was identified in 30% of relatives at first screening, and 16% developed HCM during 7 years of repeated evaluation. GT led to a discharge from clinical follow-up in 46% of the study population. Survival in the relatives was good.
(© 2018 American Heart Association, Inc.)