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 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.