Epidemiology of typical coronary heart disease versus heart disease of uncertain etiology (atypical) fatalities and their relationships with classic coronary risk factors.

The relationships were explored of some cardiovascular risk factors to typical (TYP) and atypical (ATYP) fatal coronary events (CHD).Thirteen cohorts of 40-59 year-old men of the Seven Countries Study were followed-up for 40 years (N = 9704 heart disease free subjects). Fatal TYP-CHD were classified when manifested as myocardial infarction, other acute coronary syndromes, angina pectoris and sudden death; and as ATYP-CHD when manifested only as heart failure or arrhythmia in the absence of other clear etiologies. Death rates were computed for single countries separately for TYP and ATYP and for different lengths of follow-up. Cox models included: age, smoking habits, systolic blood pressure (SBP), serum cholesterol (CHOL), forced expiratory volume in ¾ sec (FEV) and diabetes.TYP-CHD was more common in North American and Northern European countries, while ATYP-CHD were more common in Southern and Eastern Europe. Age at death was 5 years greater for ATYP-CHD than for TYP-CHD. Cox models in the pool of 13 cohorts showed that coefficient for age was significantly larger for ATYP-CHD (hazard ratio, HR: 2.36; confidence intervals CI: 2.18 - 2.26) versus TYP-CHD (HR 1.50, CI 1.43-1.58) while coefficients for CHOL was larger and significant for TYP-CHD (HR 1.29, CI 1.22-1.35) but not for ATYP-CHD (HR 0.93, CI 0.85-1.03). SBP, smoking habits, FEV and diabetes all predicted both conditions almost equally.The different relationships of CHOL and age with the two types of fatal CHD suggest that the two groups of manifestations may belong to different diseases.