Preinfarction blood pressure and smoking are determinants for a fatal outcome of myocardial infarction: a prospective analysis from the Finnmark Study

Abstract

Background: Serum cholesterol levels, blood pressure, and smoking are the classic coronary risk factors, but what determines whether a myocardial infarction will be fatal or not?

Objective: To investigate cardiovascular risk factors that may influence survival in subjects with coronary heart disease (myocardial infarction and sudden death).

Subjects and methods: All inhabitants aged 35 to 52 years in Finnmark County, Norway, were invited to a cardiovascular survey in 1974-1975 and/or 1977-1978. Attendance rate was 90.5%. A total of 6995 men and 6320 women were followed up for 14 years with regard to incident myocardial infarction and sudden death. Predictors for 28-day case fatality rate after first myocardial infarction were analyzed.

Results: During 186 643 person-years, 635 events among men and 125 events among women were registered. The case fatality rate was 31.6% in men and 28.0% in women (P =.50). Among men (women) with baseline systolic blood pressure lower than 140 mm Hg, the 28-day case fatality rate was 24.5% (22.6%), among those with systolic blood pressure of 140 through 159 mm Hg, the case fatality rate was 35.6% (28.2%), and among those with systolic blood pressure of 160 mm Hg or higher, the case fatality rate was 48.2% (41.7%). Of the 760 subjects with myocardial infarction, 348 died during follow-up. In Cox regression analysis, systolic blood pressure at baseline was strongly related to death (relative risk per 15 mm Hg, 1.22; 95% confidence interval, 1.13-1.31). Daily smoking at baseline (relative risk, 1.40; 95% confidence interval, 1.07-1.85) and age at time of event (relative risk per 5 years, 1.12; 95% confidence interval, 1.01-1.24) were additional significant risk factors, while total serum and high-density lipoprotein cholesterol levels were unrelated to survival. Similar results were obtained with diastolic blood pressure in the model.

Conclusions: Preinfarction blood pressure was an important predictor of case fatality rate in myocardial infarction. Daily smoking and age were additional significant predictors.