Long-term prognosis of different forms of coronary heart disease: the Reykjavik Study

Background While coronary heart disease (CHD) is a serious and often fatal disease the prognosis is variable and major effort has been invested in risk stratification. The purpose of this study was to examine the relation between long-term prognosis and risk factors in different clinical categories of CHD. Methods A general population sample of 9141 men, aged 34-79 at entry into the study was divided into six groups with respect to manifestations of CHD at entry: I. Symptomatic infarction. II. Silent or unrecognized infarction. III. Angina pectoris with ischaemic changes on ECG. IV. Angina without ischaemic changes. V. Angina by Rose questionnaire but not confirmed by a physician. VI. No manifestations of CHD. Results The risk factor profile varied considerably between the different categories and by life-table analysis marked differences in survival were demonstrated between the groups. The risk factors maintained their detrimental effects on prognosis in the presence of CHD. Thus, age, serum total cholesterol, impaired glucose tolerance and smoking were found by Cox's regression to be statistically significant independent risk factors of CHD mortality among men having manifestations of CHD (groups I-V). Furthermore, the composite risk score, a measure of the overall risk factor exposures had marked effect on the prognosis of the various CHD groups. When the comprehensive risk factor score for both CHD mortality and all-cause mortality was accounted for marked differences persisted in the long-term prognosis. Compared to those without CHD the infarct groups had about a 7.6- and 3.7-fold risk of dying from CHD and all causes respectively. Those with angina had from 2.5- to 3.2-fold risk of CHD mortality and 1.7- to 2.2-fold risk of all-cause mortality depending on the subgroup of angina, again compared to those without manifestations of CHD. Conclusion Different categories of CHD had different risk factor profiles and the long-term prognosis resulted from a complex interplay between those factors and the diagnostic category of CHD. The risk factors maintained their detrimental effects on prognosis in the presence of CHD and after accounting for the comprehensive risk factor score marked differences persisted in the long-term prognosis, being worst for those having suffered a myocardial infarction, either symptomatic or silent.