Coronary Artery Bypass Grafting and Atrial Fibrillation: Causal Insights from Mendelian Randomization and Retrospective Cohort Analysis

Background: This study aimed to investigate the causal relationship between coronary artery bypass grafting (CABG) and atrial fibrillation (AF) using Mendelian Randomization (MR) and a retrospective cohort from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Methods: We performed two-sample MR analysis using GWAS summary statistics (UK Biobank and EBI) to identify genetic instruments for CABG, followed by sensitivity analyses (MR-Egger, weighted median) to validate causality. Concurrently, 1,835 ICU patients from MIMIC-IV were analyzed via multivariable logistic regression to assess CABG-AF association, stratified by age, hemodynamic, and coagulation profiles. Results: MR analysis demonstrated a robust causal effect of CABG on AF (IVW OR=1.8, P=2.33×10??), corroborated by cohort data showing doubled AF risk post-CABG (OR=2.1, 95% CI:1.4–3.1, P<0.001). Subgroups with autonomic instability (low heart/respiratory rates) or coagulopathy (INR>2.5) exhibited heightened susceptibility. Conclusion: CABG independently elevates AF risk via autonomic, inflammatory, and hemostatic pathways, necessitating tailored perioperative monitoring and prophylactic interventions.