The Spectrum of Echocardiographic and Electrocardiographic Abnormalities in Nonaffected Relatives of Patients with Hypertrophic Cardiomyopathy: A Transverse and Longitudinal Study

Abstract

We studied 122 relatives (18 parents, 33 siblings, 57 offspring, 10 nephews and 4 nieces; mean age 34 ± 19 years) of 33 patients with hypertrophic cardiomyopathy (HC) to analyze the incidence and clinical significance of electrocardiographic and echocardiographic abnormalities. On the basis of conventional echocardiographic criteria 12 first-degree relatives were considered to be affected by HC. Thirteen first-degree relatives and 1 niece were judged as having probable but not definite HC, i.e. left ventricular (LV) wall thicknesses over the 95% upper limit of confidence interval for age and body surface area or borderline ventricular septal thickness but a septal-to-free wall thickness ratio ≧ 1.3 in the absence of an identifiable origin. Ninety relatives had normal echocardiographic findings. The remaining 6 subjects were found to have essential hypertension and were therefore excluded from consideration. Electrocardiogram (ECG) showed major or minor abnormalities in all relatives with HC, in 7 of the 14 probably affected by HC and in 20 of the 90 with normal echocardiogram. Of the 122 relatives 44 (38 with normal echocardiogram and 6 probably affected by HC) were reexamined over a mean period of 4.3 years (range 2-7). In the course of the follow-up 3 subjects modified their cardiac status. Two offspring who had at entry LV hypertrophy at ECG as isolated cardiac abnormality developed HC over a period of 5 years. A sibling who had only minor electrocardiographic abnormalities in the first study became probably affected by HC 3 years later. Our investigation reinforces the notion that in relatives of patients with HC an abnormal ECG may precede the development of the disease. Also, there is some evidence from our data suggesting that family members with static cardiac abnormalities at serial investigations could be considered gene carriers of HC.