Hypertrophic cardiomyopathy (HCM) is a genetic disease with delayed cardiac expression. Family screening strategy includes cardiac screening that may be guided by predictive genetic testing (PGT). However, little is known about the impact of PGT and the risk factors present at the very early stage of the disease.

Our study aims to evaluate the impact of predictive genetic testing on the rate of initiation of cardiac screening, to estimate the penetrance of HCM and to determine the frequency of risk factors (RF) for sudden cardiac death in individuals at preclinical stage without HCM.

We studied 60 consecutive relatives in a single center (31 women and 29 men, mean age: 34±16.3 years) without history of HCM before genetic testing and who were mutation carriers after PGT. Cardiac screening was initiated before PGT in only 37%, and was started after PGT in 63%. Echocardiographic criteria for HCM were observed in 17% (28% of men but 6% of women, 17% of MYH7 mutation carriers but 0% in MYBPC3 carriers). Among mutation carriers without hypertrophy (n=50), 1 had non-sustained ventricular tachycardia, 2 had non-explained syncope and 5 presented with family history of sudden death. In addition, 14% had dilated left atrium, 2% a high risk mutation and 8% practiced intense physical activity. Moreover, 10% (2/21) of carriers who performed MRI had cardiac fibrosis and 3% (1/32) of carriers who performed Holter monitoring had significant premature ventricular beat (PVB>240/day).

The assessment of HCM causal mutations in relatives seems to be an important step to initiate cardiac screening. The penetrance of HCM seems to be higher in the male population and in MYH7 rather than in other genes mutation carriers. Mutations carriers at a preclinical stage without hypertrophy may have individual risk factors of sudden cardiac death. Further study of a larger population may be useful to confirm these results.