BACKGROUND: Results on the association between P-wave duration and the risk of atrial fibrillation (AF) are conflicting.

OBJECTIVE: The purpose of this study was to obtain a detailed description of the relationship between P-wave duration and the risk of AF.

METHODS: Using computerized analysis of electrocardiograms from a large primary care population, we evaluated the association between P-wave duration and the risk of AF. Secondary end-points were death from cardiovascular causes and putative ischemic stroke. Data on drug use, comorbidity, and outcomes were collected from administrative registries.

RESULTS: A total of 285,933 individuals were included. During median follow-up period of 6.7 years, 9550 developed AF, 9371 died of a cardiovascular cause, and 8980 had a stroke. Compared with the reference group (100-105 ms), individuals with very short (≤89 ms; hazard ratio [HR] 1.60, 95% confidence interval [CI] 1.41-1.81), intermediate (112-119 ms; HR 1.22, 95% CI 1.13-1.31), long (120-129 ms; HR 1.50, 95% CI 1.39-1.62), and very long P-wave duration (≥130 ms; HR 2.06, 95% CI 1.89-2.23) had an increased risk of incident AF. With respect to death from cardiovascular causes, we found an increased risk for very short (≤89 ms; HR 1.20, 95% CI 1.06-1.34), long (120-129 ms; HR 1.11, 95% CI 1.04-1.19), and very long P-wave duration (≥130 ms; HR 1.30, 95% CI 1.21-1.40) compared with the reference group (106-111 ms). Similar but weaker associations were found between P-wave duration and the risk of putative ischemic stroke.

CONCLUSION: In a large primary care population we found both short and long P-wave duration to be robustly associated with an increased risk of AF.