Objectives: This study was designed to evaluate the presence or absence of atypical T wave evolution in patients with a postinfarction pericardial effusion but without clinically recognized postinfarction pericarditis. A second purpose was to evaluate the frequency of atypical T wave evolution in a previous study of postinfarction pericarditis.
Background: Electrocardiographic (ECG) criteria involving the evolution of the T wave after an acute myocardial infarction were recently described in patients with regional postinfarction pericarditis. Atypical T wave evolution was found to have a sensitivity of 100% and a specificity of 77% for clinically recognized regional postinfarction pericarditis with or without a pericardial effusion.
Methods: The hospital records and serial ECGs of 20 patients with clinically recognized postinfarction pericarditis (Group I) were reviewed. The records and serial ECGs 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 infarction with definite or inferred postinfarction pericarditis.
Conclusions: 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 pericardial effusion existed in the absence of clinically recognized pericarditis. Fifteen percent of patients with atypical T wave evolution had a non-Q wave infarction with definite or inferred pericardial involvement. Thus, the presence of atypical T wave evolution may be a more sensitive indicator of a transmural infarction than the development of a Q wave.