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 > or = 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.(ABSTRACT TRUNCATED AT 250 WORDS)