Background: Autosomal dominant inheritance is reported in arrhythmogenic right ventricular cardiomyopathy (ARVC) but the prevalence of the familial and sporadic forms in the general population is unknown.
Aim: To evaluate the familial occurrence and clinical features of ARVC in the genetically homogenous Finnish population.
Methods: The study included 29 Finnish ARVC index patients and 135 relatives from 21 families evaluated. They underwent echocardiography, 24-hour electrocardiographic monitoring, signal-averaged electrocardiography, and exercise stress test.
Results: Twenty-two index patients had ventricular arrhythmias as first manifestation, and three developed arrhythmias later. The right ventricle (RV) was mildly affected in 22 and strongly dilated in 7 index patients. Patients with dilated RV manifested first symptoms at younger age (mean 28 years) than those without RV dilatation (mean 38 years). Of the 135 relatives, ARVC was present in 12 (9%) patients belonging to 5 of the 21 families studied, resulting in 24% familial involvement. In addition, 46 relatives (34%) had subtle cardiac abnormalities, suggesting subclinical presentation.
Conclusions: The ARVC in Finland presents with distinct arrhythmic and RV dilative subtypes. The sporadic disease is similar to the familial one which may reflect low penetration in relatives. The proportion of familial manifestation of ARVC in Finland seems comparable to that elsewhere in Europe.