PR-Interval Components and Atrial Fibrillation Risk (from the Atherosclerosis Risk in Communities Study).

Reports on the association between the PR-interval and atrial fibrillation (AF) are conflicting. We hypothesized that inconsistencies stem from that fact that the PR-interval represents a composite of several distinct components. We examined the associations of the PR-interval and its components (P-wave onset to P-wave peak duration, P-wave peak to P-wave end duration, and PR-segment) with incident AF in 14,924 participants (mean age 54 ± 5.8 years; 26% black; 55% women) from the Atherosclerosis Risk In Communities study. The PR-interval and its components were automatically measured at baseline (1987 to 1989) from standard 12-lead electrocardiograms. PR-interval >200 ms was considered prolonged and values above the ninety-fifth percentile defined abnormal PR-interval components. AF was ascertained during follow-up through December 31, 2010. Over a median follow-up of 21.2 years, 1,985 participants (13%) developed AF. Prolonged PR-interval was associated with an increased risk of AF (hazard ratio [HR] 1.19, 95% confidence interval [CI] 1.02 to 1.40). However, PR-interval components showed varying levels of association with AF (P-wave onset to P-wave peak duration: HR 1.57, 95% CI 1.31 to 1.88; P-wave peak to P-wave end duration: HR 1.20, 95% CI 0.99 to 1.46; and PR-segment: HR 1.05, 95% CI 0.85 to 1.29). In addition, the components of the PR-interval had weak-to-moderate correlation with each other (correlation r ranged from -0.44 to 0.06). In conclusion, our findings suggest the PR-interval represents a composite of distinct components that are not uniformly associated with AF. Without considering the contribution of each component, inconsistent associations between the PR-interval and AF are inevitable.