The electrocardiographic diagnosis of regional pericarditis in acute inferior myocardial infarction.

The diagnosis of postinfarction localized (regional) pericarditis has remained elusive. During the course of a recent study of patients with fatal free-wall rupture, an atypical pattern of T-wave evolution was observed during the days preceding death. It was learned, from autopsy examination, that these electrocardiographic changes were due to the associated localized pericarditis, rather than the rupture, per se. Therefore, this investigation was undertaken to ascertain if the same atypical T-wave changes occur in patients with postinfarction localized pericarditis, but without free-wall rupture, and to determine if the frequency of those changes differs between those patients with inferior and those with anterior postinfarction pericarditis. Forty-three patients with regional postinfarction pericarditis were identified clinically. They were divided into three groups, anterior (17), inferior (17) and lateral or posterior (9) myocardial infarction. In this report those patients with anterior regional postinfarction pericarditis are compared with those with inferior postinfarction pericarditis. It was found that an atypical T-wave evolution pattern--either persistently positive T-waves after 48 h or reversal of initially inverted T-waves after 48 h--existed in every patient irrespective of infarct location. However, the two atypical patterns of T-wave evolution occurred with distinctly different frequencies between the two sites of infarction. With inferior postinfarction pericarditis, gradual reversal of initially inverted T-waves occurred in 14 patients (82%) while only three (18%) had persistently positive T-waves. Conversely, among patients with anterior postinfarction pericarditis, reversal after inversion occurred in five of 17 patients (29%) while 12 of 17 patients (71%) had persistently positive deflections (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)