Hereditary heart diseases are typically characterized by autosomal dominant inheritance and delayed cardiac expression. Predictive genetic testing is offered to asymptomatic relatives to allow targeted medical care with early therapeutics in order to reduce the risk of complications (sudden death, heart failure). Psychological and sociological issues related to predictive testing are however complex and have been poorly studied. Predictive genetic testing is performed in our multidisciplinary out-patient clinic dedicated to cardiogenetics since 1999.

To evaluate our practices regarding predictive genetic testing for hereditary heart diseases and study the behavior of relatives after pre-test consultation (information phase), especially regarding a waiting period that was offered before blood sampling.

We retrospectively studied records from 304 consecutive relatives seen in our department and have requested predictive genetic testing. Underlying diseases in the families were HCM (60%), DCM (17%), ARVC (15%), LQT (5%), Brugada syndrome (2%) and other (1%). A total of 21 different genes were analyzed and most frequent ones were MYBPC3 (97), MYH7 (77), LMNA (37), PKP2 (29) and TNNT2 (16). There were 260 adults and 44 minors. At the time of the first consultation, the average age was 37 years, and 83% of the relatives previously had a cardiac checkup (echocardiography for 71%).

After first multidisciplinary consultation, 22 relatives (8%) dropped out of procedure (did not performed blood sampling) and 11 relatives (3%) performed blood sampling but did not come back to know their results. Blood sample was delayed for 70% of relatives and immediate for 30%. A mutation was present in 36% of relatives (leading to careful follow-up and cascade screening in offspring) and absent in 64% (they were reassured and discharged from clinic).

We observed a high level of genetic uptake after initial consultation but a minority of relatives decided to stop or delay the procedure. These results suggest the benefit of a waiting period before blood sampling and illustrate the importance of a multidisciplinary team in this setting.