Prognostic significance of abnormal P wave morphology and PR-segment displacement after ST-elevation myocardial infarction

Introduction: Atrial infarction is uncommonly diagnosed and data on its significance are limited. Its incidence in ST-elevation myocardial infarction (STEMI) reportedly ranges from 0.7-42%. Certain atrial ECG changes, such as abnormal P wave morphology suggestive of atrial involvement have been associated with 90-day mortality after STEMI. However, whether atrial ECG changes are associated with short (30-day) or long-term (1-year) mortality have not been studied.

Methods: We examined index ECG in 224 consecutive STEMI. Demographics, clinical variables, peak troponin I, ejection fraction, and angiographic data were collected. Atrial ECG patterns were examined and correlated with mortality.

Results: Length of stay was longer with abnormal P waves (p=0.008) or PR displacement in any lead (p=0.003). Left main coronary disease was more prevalent with abnormal P wave (p=0.045). Abnormal P wave morphology in any lead was associated with higher 30-day (OR 3.09 (1.35-7.05)) and 1-year mortality (OR 5.33 (2.74-10.36)). PR displacement in any lead was also associated with increased 30-day (OR 2.33 (1.03-5.28)) and 1-year mortality (OR 6.56 (3.34-12.86)). Abnormal P wave, PR depression in II, III and AVF, and elevation in AVR or AVL were associated with increased 1-year mortality (OR 12.49 (5.2-30.0)) as was PR depression in the precordial leads (OR 21.65 (6.82-68.66)). After adjusting for age, ejection fraction, peak troponin I, and left main disease, PR displacement in any lead was associated with increased 1-year mortality (adjusted OR 6.22 (2.33-18.64)).

Conclusion: PR segment displacement in any lead, found in 31% of patients with STEMI, independently predicted 1-year mortality.