T-WAVE CHANGES CONSISTENT WITH EPICARDIAL INVOLVEMENT IN ACUTE MYOCARDIAL-INFARCTION - OBSERVATIONS IN PATIENTS WITH A POSTINFARCTION PERICARDIAL-EFFUSION WITHOUT CLINICALLY RECOGNIZED POSTINFARCTION PERICARDITIS

Objectives. This study was designed to evaluate the presence or absenc e of atypical T wave evolution in patients with a postinfarction peric ardial effusion but without clinically recognized postinfarction peric arditis. A second purpose was to evaluate the frequency of atypical T wave evolution in a previous study of postinfarction pericarditis. Bac kground. Electrocardiographic (ECG) criteria involving the evolution o f the T wave after an acute myocardial infarction were recently descri bed in patients with regional postinfarction pericarditis. Atypical T wave evolution was found to have a sensitivity of 100% and a specifici ty of 77% for clinically recognized regional postinfarction pericardit is with or without a pericardial effusion. Methods. The hospital recor ds and serial ECGs of 20 patients with clinically recognized postinfar ction pericarditis (Group I) were reviewed. The records and serial ECG s of 20 additional patients with a postinfarction pericardial effusion without clinically recognized postinfarction pericarditis (Group II) were also examined. The type of postinfarction T wave pattern, typical or atypical, was recorded in both groups. Results. All 20 patients in Group I had atypical T wave evolution. Among the 20 patients in Group II, every patient also had atypical T wave evolution. Fifteen percent of all 40 patients with atypical T wave evolution had a non-Q wave in farction with definite or inferred postinfarction pericarditis. Conclu sions. The high sensitivity of atypical T wave evolution in diagnosing regional postinfarction pericarditis was confirmed. However, similar T wave alterations were also observed when a postinfarction pericardia l effusion existed in the absence of clinically recognized pericarditi s. Fifteen percent of patients with atypical T wave evolution had a no n-Q wave infarction with definite or inferred pericardial involvement. Thus, the presence of atypical T wave evolution may be a more sensiti ve indicator of a transmural infarction than the development of a Q wa ve.