Effect of definition on incidence of postinfarction pericarditis. It is time to redefine postinfarction pericarditis?

P ericarditis is possibly the most common cause of chest pain after an acute transmural myocardial infarction without reperfusion.' It occurs in approximately 28% to 40% of fatal transmural infarctions,2-8 and a pericardial effusion is detectable by serial echocardiograms in 28% to 63% of patients with a nonfatal transmural infarction.9-12 Yet the clinically reported frequency of postinfarction pericarditis ranges between 7%13 and 41%.1 Such a wide range seems inconsistent with the narrower frequency range determined by pathological examination2-8 and serial echocardiograms.9-12 Assuming that the wide frequency range of clinically diagnosed postinfarction pericarditis is due to a difference in the clinical definition among various studies, whereas the pathological and echocardiographic frequencies of postinfarction pericarditis and postinfarction pericardial effusion, respectively, are due to more precise, objective diagnostic criteria and observations, the present report reviews the clinical frequency of postinfarction pericarditis according to its definition (see below) and compares it with the available pathological and echocardiographic data.