Penetrance and risk profile in inherited cardiac diseases studied in a dedicated screening clinic.

Genetically transmitted cardiomyopathies can affect several members in a family. Identification of high-risk patients could lead to a preventive treatment. We report the results of a 5-year experience of a dedicated clinic. Family screening was offered to 493 consecutive unrelated patients; 2,328 subjects (40 +/- 19 years old, 52% men) were evaluated (mean 4.4 relatives/family). Electrocardiography and echocardiography were performed in all cases; additional tests were indicated depending on the disease. Familial study was recommended because of a proband with hypertrophic cardiomyopathy (HC) in 57%, idiopathic dilated cardiomyopathy (IDC) in 14%, arrhythmogenic right ventricular cardiomyopathy (ARVC) in 2%, left ventricular noncompaction in 2%, Brugada syndrome (BS) in 15%, long QT syndrome (LQTS) in 3%, and other conditions in 6%. Familial disease was confirmed in 164 (39%); 43% with HC, 47% with IDC, 25% with ARVC, 33% with left ventricular noncompaction, 28% with BS, and 30% with LQTS. Two hundred twenty-two (44 +/- 20 years old, 60% men) affected relatives were identified (129 of whom were newly diagnosed). Sixty-four patients were newly diagnosed with HC, 40 with IDC, 2 with ARVC, 5 with left ventricular noncompaction, 14 with BS, and 2 with LQTS, in whom appropriate risk stratification and medication, if needed, were initiated (specific medication in 40, 31.0%). Cardioverter-defibrillator implantation was indicated in 4 relatives for primary prevention. Ninety-two (18.7%) had a family history of sudden death (FHSCD). Consanguinity was rare but significantly associated to a higher percentage of family disease (75.0% vs 38.3%, p = 0.003) and family history of sudden death (42.1% vs 17.8, p <0.001). In conclusion, the prevalence of familial disease in inherited cardiac conditions is high. Systematic familial study identified many asymptomatic affected patients who could benefit from early treatment to prevent complications. Dedicated clinics and multidisciplinary teams are needed for proper screening programs.