Role of family history and clinical screening in the identification of families with idiopathic dilated cardiomyopathy in Johannesburg, South Africa

Background. Familial disease is implicated in 20 - 50% of cases of idiopathic dilated cardiomyopathy (IDCM) worldwide. The contribution of familial factors to IDCM in the Johannesburg area, South Africa, is unknown.Objectives. To describe the demographic details of patients with IDCM who presented at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH), and to determine if there is evidence of familial disease through family history assessment and clinical screening of relatives.Methods. This was a single-centre, cohort study performed at a quaternary care centre at CMJAH. Fifty unrelated probands diagnosed with IDCM and available first- and second-degree relatives were included in the study. A three-generation family pedigree was drawn up for all 50 probands. The pedigrees were analysed to identify the presence or absence of familial disease and categorised as positive, intermediate, negative or unreliable according to the family history obtained. From the 50 proband cases, there were 21 family members available for screening for features of IDCM. Eighty-two family members (55 first-degree and 27 second-degree relatives) were screened clinically. Screening included a personal history, full physical examination, electrocardiogram (ECG) and echocardiogram.Results. The mean age at diagnosis of IDCM in the probands was 41.7 (standard deviation (SD) 12.4) years. The majority of probands were males (n=38; 76%). Of 50 pedigrees analysed, 14 (28%) were positive and likely to be indicative of familial dilated cardiomyopathy (DCM), and 9 (18%) patients were at intermediate risk of familial disease. Eighty-two asymptomatic family members were screened, with a median age of 33 (range 11 - 76) years. No asymptomatic family members were identified with features of DCM or presymptomatic DCM. Eleven of the 21 families screened had relatives with possible presymptomatic DCM identified by abnormalities on the echocardiogram in 3 families (14.3%) (4 individuals; all first-degree relatives of the index case) or identified on the basis of a conduction defect (an arrhythmia or first-/ second-/third-degree heart block) in 8 families (72.7%) (11 individuals; 9 first-degree and 2 second-degree relatives).Conclusions. Screening for IDCM should include a three-generation family history and clinical screening of all first-degree family members. As IDCM has an age-related penetrance, at-risk family members should receive follow-up for screening to assess symptoms and signs of IDCM. Genetic testing would potentially identify family members at high risk, who would benefit from screening; this might be a less expensive option