THE SPECTRUM OF ECHOCARDIOGRAPHIC AND ELECTROGASTROGRAPHIC - ABNORMALITIES IN NONAFFECTED RELATIVES OF PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY - A TRANSVERSE AND LONGITUDINAL-STUDY

We studied 122 relatives(18 parents, 33 siblings, 57 offspring, 10 nep hews and 4 nieces; mean age 34 +/- 19 years) of 33 patients with hyper trophic cardiomyopathy (HC) to analyze the incidence and clinical sign ificance of electrocardiographic and echocardiographic abnormalities. On the basis of conventional echocardiographic criteria 12 first-degre e relatives were considered to be affected by HC. Thirteen first-degre e relatives and 1 niece were judged as having probable but not definit e HC, i.e. left ventricular (LV) wall thicknesses over the 95 % upper limit of confidence interval for age and body surface area or borderli ne ventricular septal thickness but a septal-to-free wall thickness ra tio greater than or equal to 1.3 in the absence of an identifiable ori gin. Ninety relatives had normal echocardiographic findings. The remai ning 6 subjects were found to have essential hypertension and were the refore excluded from consideration. Electrocardiogram (ECG) showed maj or or minor abnormalities in all relatives with HC, in 7 of the 14 pro bably affected by HC and in 20 of the 90 with normal echocardiogram. O f the 122 relatives 44 (38 with normal echocardiogram and 6 probably a ffected 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 isola ted cardiac abnormality developed HC over a period of 5 years. A sibli ng 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 abnorma l ECG may precede the development of the disease. Also, there is some evidence from our data suggesting that family members with static card iac abnormalities at serial investigations could be considered gene ca rriers of HC.