MODE OF INHERITANCE OF HYPERTROPHIC CARDIOMYOPATHY IN ICELAND - ECHOCARDIOGRAPHIC STUDY

An abnormally thick interventricular septum (.gtoreq. 1.3 cm) was used as an echocardiographic marker to find the inheritance pattern of hypertrophic cardiomyopathy among relatives of 8 patients who had that disease at necropsy. Normal subjects (40) served as a control group. Family members (58) were examined and 18 (41%) of the 44 1st relatives had hypertrophic cardiomyopathy. The overall inheritance pattern was consistent with an autosomal dominant genetic disorder and in 1 family a recessive trait could be excluded. The diagnosis of hypertrophic cardiomyopathy can be difficult clinically as only 13% of patients had serious symptoms and only 30% had abnormal auscultatory findings. The ECG is a useful screening test among relatives as it was abnormal in 20 (87%) of those who had an abnormally thick septum. Symmetric septal hypertrophy was found in 30% of patients with cardiomyopathy in this study and only 17% had clinical evidence of obstruction.