Frequency and phenotypes of familial dilated cardiomyopathy.

OBJECTIVES: This prospective study was performed to analyze the frequency and clinical characteristics of idiopathic dilated cardiomyopathy (DCM).

BACKGROUND: Despite several previous reports on families with DCM, most cases are still believed to be sporadic, and specific clinical findings of the familial form are not well defined.

METHODS: In 445 consecutive patients with angiographically proven DCM, we obtained detailed family histories to construct pedigrees and examined 970 first- and second-degree family members.

RESULTS: Familial DCM was confirmed in 48 (10.8%) of the 445 index patients and was suspected in 108 (24.2%). The 156 patients with suspected or confirmed familial disease were younger at the time of diagnosis (p < 0.03) and more often revealed electrocardiographic changes (p = 0.0003) than patients with nonfamilial disease. Among the families of the 48 index patients with confirmed familial disease, five phenotypes of familial DCM could be identified: 1) DCM with muscular dystrophy; 2) juvenile DCM with a rapid progressive course in male relatives without muscular dystrophy; 3) DCM with segmental hypokinesia of the left ventricle; 4) DCM with conduction defects; and 5) DCM with sensorineural hearing loss.

CONCLUSIONS: Up to 35% of patients with DCM may have an inherited disorder. Distinct clinical phenotypes can be observed in some families, suggesting a common molecular cause of the disease.