First-degree atrioventricular block is significantly associated with incident atrial fibrillation in the population predominantly including participants aged ≥ 60 years.

Some previous studies demonstrated that first-degree atrioventricular block (f-AVB) was associated with incident atrial fibrillation (AF), while evidence is scarce regarding the association between f-AVB and incident AF in older populations. Therefore, we sought to investigate the association of f-AVB with incident AF in the population predominantly including participants aged ≥ 60 years. Eligible participants were residents in Kanazawa City, Japan aged ≥ 40 years who underwent 12-lead ECG at the National Japanese Health Check-up in 2013. Participants with AF detected at the baseline exam and those without adequate follow-up were excluded. f-AVB was defined as PR interval ≥ 220 ms based on the Minnesota code (6-3). The cumulative incidence of AF was estimated by the Kaplan-Meier curve analysis, and statistical significance was evaluated by the Log-rank test. Unadjusted and adjusted hazard ratios (HRs) were computed by Cox proportional hazard models. HRs were adjusted for conventional risk factors for AF. 37,730 participants (mean age, 72.3 ± 9.6 years; male, 37%) were included. Baseline f-AVB was observed in 667 (1.8%) participants. During the median follow-up period of 5 years (interquartile range, 4.0-5.0 years), 691 cases of incident AF were observed. A 5-year cumulative incidence of AF was significantly higher in f-AVB (+) group compared with f-AVB (-) group (6.8% vs 2.1%, p < 0.01). In the fully adjusted model, f-AVB was significantly associated with incident AF (HR, 1.75; 95% confidence interval 1.25-2.45; p value < 0.01). f-AVB was independently associated with incident AF in the population predominantly including participants aged ≥ 60 years.