Prognostic significance of first-degree atrioventricular block in a large Asian population: a prospective cohort study

OBJECTIVE: To investigate the prognostic significance of first-degree atrioventricular block (AVB) in Asian populations. DESIGN AND SETTING: Participants (N=9634) from the Northeast China Rural Cardiovascular Health Study were included. The first-degree AVB was defined as PR (from the beginning of the P wave to the beginning of the QRS complex on an electrocardiogram) interval >200 ms, and primary composite outcome (all events) included new onset cardiovascular disease (CVD) and mortality. Cox regression and restricted cubic spline were used to identify the associations of PR interval or first-degree AVB with end points. Furthermore, the relationship between new-onset CVD and mortality and first-degree AVB was separately evaluated. The value of first-degree AVB for predicting adverse events was evaluated by reclassification and discrimination analyses. RESULTS: During a median of 4.65 years follow-up, 524 participants developed CVD and 371 died. Compared with participants with PR ≤200 ms, those with first-degree AVB had an increased risk of all events (HR: 1.84; 95% CI 1.18 to 2.88). Furthermore, first-degree AVB was predictive of incident CVD (1.96, 1.18 to 3.23) and stroke (2.22, 1.27 to 3.90) after adjusting for conventional risk. These statistically significant associations remained unchanged after further stratification by potential confounding factors. Discrimination and reclassification analyses suggested that first-degree AVB addition could improve the conventional model for predicting adverse outcomes within 4 years. CONCLUSIONS: Our results indicated that first-degree AVB was an independent risk factor for adverse events, suggesting that it should not be considered as inconsequential factor in general population. These results have potential clinical value for identifying individuals at high risk for adverse outcomes.