Predictors, incidence, and prognostic significance of PR interval prolongation in patients with ST-segment elevation myocardial infarction

OBJECT: The relationship between PR interval prolongation during hospitalization and long-term prognosis in patients with acute ST-segment elevation myocardial infarction (STEMI) has not been elucidated. This study aimed to evaluate the prevalence, predictors, and outcomes of PR interval prolongation in a prospective cohort of patients with post-STEMI. METHODS: The values of ionized calcium were calculated as the mean level of two measurements during hospitalization. Variables from univariate analysis associated with PR interval prolongation were included in a multivariable logistic regression analysis using forward stepwise elimination to determine PR prolongation predictors. RESULTS: Among 915 patients with STEMI consecutively enrolled in this study, 87 (9.5%) patients developed first-degree atrioventricular block (PR interval prolongation >200 ms]. Lower calcium values during hospitalization, higher age, and male sex were strongly correlated with the development of PR interval prolongation. During the median follow-up period of 31 months (interquartile range: 22-39 months), 64 all-cause deaths (endpoint) were registered. After adjusting for confounding covariates via Cox regression analyses, PR interval prolongation was independently associated with poorer outcomes (hazard ratio 5.37; 95% confidence interval, 1.85-15.62; P = 0.002). CONCLUSION: Prolongation of the PR interval is an independent predictor of long-term mortality in patients with STEMI during hospitalization.