Pericarditis of acute myocardial infarction.

Forty patients with acute myocardial infarction and pericarditis (AMI-P) were encountered over a three-year period. The incidence of AMI-P was 7.2 percent (40 of 554 patients). Fifty consecutive patients with acute transmural infarction without pericarditis (AMI-C) were used as a control group. There were no significant differences between the AMI-P and AMI-C groups regarding age, sex, infarct location, hospital stay or mortality. Painful symptoms of pericarditis were experienced by 37 patients (92 percent), all of whom had developed symptoms by the fourth hospital day. The pericardial friction rub lasted three days or less in 34 patients (85 percent), but an occasional rub could be heard for up to eight days. Twenty patients with AMI-P (50 percent) developed pleural effusions and/or parenchymal pulmonary infliltrates. Twenty-eight AMI-P patients (70 percent) were thought to have had congestive heart failure (CHF) on the basis of their symptoms and physical findings. Radiographic examination could confirm only 13 cases of CHF among the 28 patients in whom the diagnosis was made clinically. Glucocorticoids were given parenterally to 31 of the 37 patients (84 percent) who had symptomatic pericarditis and was felt to be effective in ameliorating painful symptoms. Followup data was obtained on 28 of the 32 surviving patients. Five patients (15 percent) had seven episodes of the postmyocardial infarction syndrome (PMIS). Pericarditis is generally a shortlived complication of acute myocardial infarction. Pleural and parenchymal pulmonary abnormalities are common and probably account for the tendency to "overdiagnose" CHF in patients with AMI-P. PMIS appears to occur more frequently in patients who have had pericarditis at the time of the acute myocardial infarction.