Clinical first myocardial infarction: coronary artery disease and old infarcts in 53 consecutive fatal cases from a coronary care unit.

The frequency and size of previous unrecognized myocardial infarction in patients with first clinical diagnosed acute myocardial infarction are unknown. In this study, 53 consecutive patients with clinical first acute myocardial infarction which proved fatal were studied postmortem. All showed acute infarction (inclusion criterium). Acute coronary thrombosis was found in 51 (96%). One-, two-, and three-vessel disease diagnosed by postmortem coronary angiography (diameter stenosis greater than or equal to 75%) was present in 17 (32%), 22 (42%), and 14 (26%), respectively. One or more old infarcts were found in 24 of the cases (45%) despite no history of previous myocardial infarction. Old infarcts were found in 86% of the hearts with three-vessel disease and in 55% of the hearts with two-vessel disease, but none were found in the hearts with one-vessel disease. The median weight of the old infarcts was 4 grams (range: 0.5 to 25 grams) corresponding to 5% (0.5 to 14%) of the ventricular myocardium. Thus, two- or three-vessel coronary artery disease and old infarcts are often present in patients dying from their clinical first acute myocardial infarction.