Quantitative comparison of extent of coronary narrowing and size of healed myocardial infarct in 33 necropsy patients with clinically recognized and in 28 with clinically unrecognized ("silent") previous acute myocardial infarction.

Clinical and necropsy observations are described in 61 patients with a healed transmural myocardial infarction, 33 with and 28 without a clinical history of acute myocardial infarction. There were no significant differences between the 2 groups of patients in mean age, sex, or frequency of angina pectoris, chronic congestive heart failure, systemic hypertension, sudden coronary death, or fatal acute myocardial infarction. Compared with the patients with clinically recognized acute myocardial infarction, the patients with clinically unrecognized (silent) infarction had a significantly (p less than 0.05) higher incidence of diabetes mellitus (43 versus 15%), death from noncardiac causes (39 versus 9%), posterior (inferior) wall infarcts (82 versus 55%), and smaller infarcts (mean size 7 versus 17% of left ventricular wall). The patients with and without clinically recognized infarction had similar numbers of the 4 major coronary arteries severely (76 to 100% in cross-sectional area) narrowed (mean 2.8 versus 2.9/4.0 per patient), insignificant differences in incidence of severe narrowing of the left main coronary artery (18 versus 29%), similar overall percents of 5 mm segments of the 4 major coronary arteries severely narrowed (43 versus 42%), and similar percents of severely narrowed 5 mm segments of the right (46 versus 55%), left anterior descending (39 versus 33%), and left circumflex (41 versus 41%) coronary arteries.