Familial occurrence of coronary heart disease: effect of age at diagnosis.

The occurrence of coronary heart disease and its main risk factors were assessed among the first degree relatives of 309 men from South and East Finland, including 203 men with fatal or nonfatal myocardial infarction and 106 healthy reference men under age 56 years. The younger the patient at the diagnosis of a first myocardial infarction, the more common was coronary heart disease in his parents and siblings. The risk of having coronary heart disease by age 55 was, respectively, 11.4, 8.3 and 1.3 times greater in the South and 6.7, 3.6 and 1.8 times greater in the East for the brothers of patients than for the brothers of reference subjects depending on whether the diagnosis of myocardial infarction in the patient had first been established before the age of 46 years of age 46 to 50 years or at age 51 to 55 years. Hypertension and hyperlipidemia, but none of the other risk factors studied, were most common among the relatives of the youngest patients and diminished in frequency with advancing age of the patient. Most of the strong familial component in coronary heart disease of early onset thus appears to be mediated by familial hyperlipidemias and hypertension. It is suggested that the risk of premature coronary heart disease in the persons at highest risk could be largely eliminated if information about family history were used to identify such persons at an early stage and if they were treated properly for their correctable risk factors.