Association between PR segment displacement with adverse in-hospital outcome after thrombolysis in patients with acute ST elevation myocardial infarction

Background: Atrial ischemia produces similar changes in the PR-segment as ventricular ischemia in the ST-segment. The occurrence of PR segment displacement on the admission ECG can predict the risk of developing adverse in-hospital outcomes, especially for STEMI patients, and is strongly correlated with the severity of acute ST-elevated MI. However, further studies are needed to see this relationship between PR segment displacement and in-hospital outcomes in patients with STEMI. Method: This prospective observational study was conducted at the National Institute of Cardiovascular Diseases (NICVD), Dhaka, Bangladesh, from February 2019 to September 2020 on 200 patients with two equally divided groups based on PR segment displacement: Group I with PR displacement ≥ 0.5mm and Group II with PR displacement <0.5 mm. Only the initial ECGs at the time of arrival to the emergency department were used to calculate PR segment displacement. A PR segment elevation or depression of ≥0.5mm was considered significant. Arrhythmia, heart failure, cardiogenic shock, duration of hospital stay, and death were observed during the index hospitalization. Results: Out of 200 patients, 112 had PR segment displacement. Among patients of PR segment displacement, PR segment depression (59.82%) was higher than elevation (40.18%). All of the atrial arrhythmias were observed more frequently in group I in comparison to group II, and among them, atrial fibrillation was significantly higher in group I (28% vs 10%; p=0001). Cardiogenic shock was also observed more in group I with significant PR depression than without significant PR depression (18% vs 8%; p=0.03). The mean hospital stay was significantly higher in group I than group II (Mean±SD = 6.05±1.84 vs 3.87±1.46 days; p<0.001). Incidence of ventricular arrhythmias, heart failure, atrial thrombus, and death didn’t differ significantly between the groups (p>0.05). The odds ratios of hypertension, heart rate, and PR segment displacement were significant in univariate analysis. In multivariate analysis after adjusting for these variables, only PR segment displacement was found to be the independent predictor for developing adverse in-hospital outcomes, with an OR of 6.54.  Conclusion: Significant PR segment displacement is associated with adverse in-hospital outcomes, especially in the form of atrial fibrillation and cardiogenic shock in patients with ST elevation myocardial infarction after thrombolytic therapy