Electrocardiographic diagnosis of postinfarction regional pericarditis. Ancillary observations regarding the effect of reperfusion on the rapidity and amplitude of T wave inversion after acute myocardial infarction.

Abstract

BACKGROUND The ECG recognition of diffuse pericarditis following acute myocardial infarction has been based on changes of the ST segment and, to a lesser extent, alterations of the PQ segment. No ECG criteria exist for the diagnosis of postinfarction regional pericarditis. Recently, it was observed that the T wave evolution follows an atypical pattern before fatal free wall rupture and that this pattern is due to the associated pericarditis. Therefore, this study was conducted on 200 patients with acute myocardial infarction to further elucidate the sensitivity and specificity of the atypical T wave changes in patients with regional postinfarction pericarditis without rupture and to assess the affect of lytic treatment on the rapidity and amplitude of postinfarction T wave evolution. METHODS AND RESULTS An analysis of the clinical courses and serial ECGs of 200 consecutive patients with acute myocardial infarction was performed. Among 43 patients with postinfarction pericarditis, the pattern of T wave evolution consistently differed from the customary postinfarction pattern of T wave evolution. This unusual evolutionary course was expressed as either persistently positive T waves 48 or more hours after infarction (67%) or premature, gradual reversal of inverted T waves to positive deflections (33%). The sensitivity and specificity of these T wave alterations were 100% and 77%, respectively. The only other processes identified that caused this type of postinfarction T wave evolution were cardiopulmonary resuscitation, reinfarction, and very small infarcts. Both reperfusion, as judged by the creatine kinase-MB curve, and patency, as assessed by the angiogram, were correlated with the rapidity and depth of T wave inversion. Ninety percent of patients with reperfusion attained a maximum T wave negativity of 3 mm or more within 48 hours after the onset of chest pain in the lead that initially displayed the greatest ST segment elevation. Seventy-six percent of patients without reperfusion attained a maximum negativity of 2 mm or less within 72 hours. Thus, like the ST segment, accelerated evolution and deepening of the T wave may be noninvasive markers of reperfusion. CONCLUSIONS First, premature reconcordancy of the ST segment and T wave after acute myocardial infarction is a sensitive, reasonably specific, and easily recognizable ECG manifestation of postinfarction regional pericarditis. Second, reperfusion is associated with accelerated evolution and deepening of the T waves following acute myocardial infarction.