Electrocardiographic PR prolongation and atrial fibrillation risk: a meta-analysis of prospective cohort studies.

BACKGROUND: Electrocardiographic PR interval prolongation is considered a benign condition, but recent studies have challenged the notion by demonstrating that prolonged PR interval is associated with an increased risk of atrial fibrillation (AF).

OBJECTIVE: The purpose of this study was to perform a meta-analysis of prospective cohort studies to evaluate the evidence supporting an association of prolonged PR interval with AF incidence.

METHODS: We searched the MEDLINE and EMBASE database (from inception to May 2014) supplemented by manual searches of references of relevant retrieved articles. Prospective cohort studies were included with hazard ratio (HR) of prolonged PR interval for incident AF.

RESULTS: The search strategy yielded 6 cohort studies meeting eligibility criteria. A total of 328,932 participants were included, with 14,191 participants suffering from AF during follow-up. Pooled HRs of prolonged PR interval for incident AF was 1.30 (95% CI: 1.13 to 1.49) using random-effect model (I(2) = 30%). There was a significant difference of combined HRs between studies with and without adjustment for taking of AV nodal blocking agents in subgroup analysis. Sensitivity analysis supported the robustness of the results.

CONCLUSIONS: Prolonged PR interval is not a totally benign condition but an independent risk factor for AF incidence. The mechanisms underlying the association of prolonged PR interval with AF incidence need further research.