Incidence and significance of heartmuscle antibodies in patients with acute myocardial infarction and unstable angina.

The incidence of heartmuscle antibodies was studied prospectively in 136 patients consecutively admitted for acute myocardial infarction (AMI) and in 95 patients with unstable angina. Heartmuscle antibodies were determined with the indirect immunofluorescence technique on days 1, 10, 20 and 30 in patients with AMI and on days 1 and 10 in patients with unstable angina. Heartmuscle antibodies were found in 16/136 AMI patients (12%) and in 3/95 (3%) with unstable angina. None of the AMI patients developed post-myocardial-infarction syndrome in the 2--4 weeks after infarction or during the one-year follow-up. The AMI patients with and without heartmuscle antibodies were comparable with respect to age, sex, site and size of infarction, incidence of early pericarditis and previous infarction.