Refining Prediction of Atrial Fibrillation Risk in the General Population With Analysis of P-Wave Axis (from the Atherosclerosis Risk in Communities Study).

Adverse atrial remodeling is associated with increased risk of atrial fibrillation (AF) and can be detected by a shift in P-wave axis. We aimed to determine whether an analysis of P-wave axis can be used to improve risk prediction of AF. We included 15,102 Atherosclerosis Risk in Communities Study participants who were free of AF at baseline. Abnormal P-wave axis (aPWA) was defined as any value outside 0 to 75 degrees on study visit 12-lead electrocardiograms. AF was determined using study visit electrocardiograms, death certificates, and hospital discharge records. Multivariable Cox regression was used to estimate hazard ratios and 95% confidence intervals (CIs) for the association of aPWA with AF. The Cohorts for Heart and Aging Research in Genomic Epidemiology-AF (CHARGE-AF) risk prediction model variables served as our benchmark. Improvement in 10-year AF prediction was assessed by C-statistic, category-based net reclassification improvement, and relative integrated discrimination improvement. During a mean follow-up of 20.2 years, there were 2,618 incident AF cases. aPWA was independently associated with a 2.34-fold (95% CI 2.12 to 2.58) increased risk of AF after adjusting for CHARGE-AF risk score variables. The use of aPWA improved the C-statistic from 0.719 (95% CI 0.702 to 0.736) to 0.722 (95% CI 0.705 to 0.739), which corresponded with a net reclassification improvement of 0.021 (95% CI 0.001, 0.040) and relative integrated discrimination improvement of 0.043 (95% CI 0.018, 0.069). In conclusion, aPWA is independently associated with AF in the general population. The use of this maker modestly improves AF prediction.