Serum Cholesterol as a Prognostic Factor after Myocardial Infarction: The Framingham Study

Abstract

▪ Objective: To determine the relation between serum cholesterol levels and the long-term risk for reinfarction, death from coronary heart disease, and all-cause mortality in persons who recover from myocardial infarction.

▪ Design: Prospective, longitudinal study.

▪ Setting: A geographically defined population-based cohort of adults participating in the Framingham Heart Study.

▪ Patients: Men (n = 260) and women (n =114), 33 to 88 years of age (mean age, 62 years), who had a history of myocardial infarction.

▪ Measurements: A complete physical examination, including electrocardiographic evaluation, blood pressure measurement, height and weight measurements, determination of smoking habits, and casual determinations of blood glucose and serum cholesterol, was done approximately 1 year after recovery from initial myocardial infarction. Patients were followed after infarction for the occurrence of reinfarction or death (mean follow-up, 10.5 years; range, 0.8 to 31.6 years).

▪ Main Results: The mean cholesterol level after infarction was 5.21 mmol/L (242.8 mg/dL); 20% of patients had levels below 5.17 mmol/L (200 mg/dL), and 22% had levels of 7.11 mmol/L (275 mg/dL) or more. Compared with patients who had cholesterol levels below 5.17 mmol/L, patients with levels of 7.11 mmol/L or more were at increased risk for reinfarction (relative risk, 3.8; 95% Cl, 1.6 to 8.7), death from coronary heart disease (relative risk, 2.6; Cl, 1.4 to 4.8), and all-cause mortality (relative risk, 1.9; Cl, 1.2 to 2.9) based on multivariate Cox regression analyses adjusted for other coronary risk factors. Intermediate cholesterol levels (5.17 mmol/L to 7.11 mmol/L) were generally not associated with increased risk. The association between elevated serum cholesterol and increased risk was strongest in men; however, elevated cholesterol levels were found to be most strongly related to death from coronary disease and to all-cause mortality in persons who were 65 years of age or more.

▪ Conclusions: Patients who have recovered from a myocardial infarction and who have high cholesterol levels are at an increased long-term risk for reinfarction, death from coronary heart disease, and all-cause mortality. Our results confirm the prognostic value of cholesterol levels measured after myocardial infarction and support the role of lipid management in this population.