Clinical features of unrecognized myocardial infarction-Silent and symptomatic. Eighteen year follow-up: The framingham study

The occurrence, prognosis and characteristics of persons with nonfatal unrecognized myocardial infarction were studied prospectively in a population of 5,127 men and women followed up biennially for 18 years. Of 259 electrocardiographically documented myocardial infarctions, 60 (23 percent) were discovered only by routine electrocardiogram at the time of biennial examination. Of these unrecognized infarctions, 32 (53 percent) were actually silent. In the other 47 percent of cases, the patients gave a history of interim symptoms judged to be compatible with acute infarction. In addition, of the 32 patients judged to have a silent infarction, 22 reported interim illnesses that could have been compatible with myocardial infarction. Only 10 of the 60 patients (17 percent) reported no interim illnesses or symptoms. Of the 28 patients with symptomatic infarction, 6 (21 percent) did not visit their physician despite severe symptoms; 20 gave a history of interim chest pain, 1 a history of epigastric pain and 7 a history of severe dyspnea. Patients who subsequently had unrecognized myocardial infarction typically visited physicians infrequently. Unrecognized myocardial infarction was distinctly rare in patients with prior angina pectoris. Patients with prior diabetes or high blood pressure appeared more likely to have unrecognized infarction. Unrecognized myocardial infarction appears to be as prevalent in the 1970's as it was in the 1950's. The reasons for this prevalence and possible solutions to the problem are discussed.