Prognostic implications of PR-segment depression in inferior leads in acute inferior myocardial infarction

Abstract

Background: Concurrent atrial ischemia is usually overlooked in acute myocardial infarction (MI) due to its subtle electrocardiographic (ECG) changes, lack of clear-cut clinical picture, and prognostic significance. PR-segment depression in the inferior leads is a simplified ECG sign for detecting possible underlying atrial ischemia. Hypothesis: The purpose of this study was to document the incidence, clinical characteristics, and prognostic implications of this ECG sign in the setting of acute inferior MI. Methods: Demographics, clinical characteristics, and outcomes of 463 consecutive patients presenting with acute inferior MI were reviewed. The in-hospital ECG was examined by two independent reviewers. The results were then compared between those with and without ECG sign. Results: Profound PR-segment depression ≥ 1.2 mm in inferior leads was found in 9 of 463 (1.9%) patients. Patients with atrial ischemia tended to present earlier (2.4 ± 2.6 vs. 7.0 ± 8.2 h, p = 0.000) and had a higher frequency of first-degree atrioventricular block (77.8 vs. 30.6%, p = 0.028) and supraventricular arrhythmias (55.5 vs. 20.2%, p = 0.022). Of greater importance, it was significantly associated with an increased rate of cardiac free-wall rupture (33.3 vs. 2.0%, p = 0.001) and in-hospital mortality (44.4 vs. 11.7%, p = 0.015). Conclusion: Profound PR-segment depression ≥ 1.2 mm in inferior leads was associated with a complicated hospital course and poor short-term outcome in acute inferior MI. These patients were at high risk for the development of atrioventricular block, supraventricular arrhythmias, and cardiac free-wall rupture.