Some lessons in cardiovascular epidemiology from Framingham.

Epidemiologic investigations have provided a portrait of the potential candidate for coronary heart disease. This is important because studies of the evolution of coronary disease in the general population reveal that it is a common disease that frequently attacks without warning, can be silent in its most dangerous form and can present with sudden death as the first symptom. Progress in identifyin- persons in jeopardy and the factors needing correction makes it theoretically possible to interrupt the chain of factors that eventuate in this disease. Coronary disease does not really begin with crushing chest pain, pulmonary edema, shock, angina or ventricular fibrillation, but rather with more subtle signs like a poor coronary risk profile. The risk factors can be treated quantitatively as ingredients of a cardiovascular risk profile and their joint effect estimated. An efficient practicable set of variables for this purpose is a casual blood test for cholesterol and sugar, a blood pressure determination, an electrocardiogram and a cigarette smoking history. With this set of variables the risk of coronary heart diseases can be estimated over a 30-fold range and 10 percent of the asymptomatic population identified in whom 25 percent of the coronary disease, 40 percent of the occlusive peripheral arterial disease and 50 percent of the strokes and congestive heart failure will evolve. The periodic use of the electrocardiogram at rest and after exercise in persons with a poor risk profile can demonstrate persons with asymptomatic ischemic cardiomyopathy due to advanced coronary artery disease. Most cases of angina pectoris or myocardial infarction represent medical failures; the conditions should have been detected years earlier for preventive management. About 30 percent of patients with infraction will shortly experience new angina, have an annual death rate of 4 percent and a fourfold increased risk of sudden death. Reinfarction will occur at an annual rate of 6 percent, and half the recurrences will be fatal. Congestive heart failure must be expected at 10 times and strokes at 5 times the rate found in the general population. Although no major innovations are required to identify candidates for coronary disease and to estimate their risk, we have much to learn about motivating changes in behavior to control risk factors. Approaches to prevention of coronary heart disease include public health measures to alter the ecology in favor of cardiovascular health, preventive medicine directed at highly vulnerable candidates and hygienic measures initiated by an informed public in its own behalf.