Postoperative atrial fibrillation increases long-term thromboembolic risk following CABG and isolated valve surgeryAtrial Fibrillation After Heart Surgery Linked to Higher Blood Clot Risk

Postoperative atrial fibrillation (POAF) is a frequent complication following cardiac surgery and has been associated with an increased risk of thromboembolic events. However, cardiac surgical populations are heterogeneous, and the long-term thromboembolic implications of POAF may differ according to the index surgical procedure. This systematic review and meta-analysis evaluated the procedure-specific association between POAF and long-term thromboembolic outcomes after adult cardiac surgery, with particular emphasis on coronary artery bypass grafting (CABG) and isolated valve surgery. PubMed and Scopus were searched from database inception through August 3, 2026. Studies reporting long-term thromboembolic outcomes in patients with new-onset POAF compared with patients without POAF were evaluated, with eligible evidence classified according to the index surgical procedure. Four observational studies were included in the primary quantitative synthesis, with two studies contributing to the CABG analysis and two to the isolated valve-surgery analysis. Adjusted hazard ratios (HRs) were pooled separately by procedure using inverse-variance methods, and a formal between-subgroup interaction test was performed. Following CABG, POAF was associated with an increased long-term thromboembolic hazard (pooled HR 1.147, 95% CI 1.053-1.249; I^2=0%). A stronger association was observed following isolated valve surgery (pooled HR 1.362, 95% CI 1.181-1.573; I^2=0%). The between-subgroup interaction was statistically significant ({chi}^2=4.10, P=0.043), providing exploratory evidence that the magnitude of the association may differ according to surgical procedure. These findings suggest that the long-term thromboembolic implications of POAF may not be uniform across cardiac surgical populations. However, because only two studies contributed to each procedure subgroup and the available evidence was observational, the interaction should be considered hypothesis-generating. Further adequately powered studies with standardized outcome definitions and procedure-specific reporting are required to confirm these findings and determine their implications for long-term risk stratification and anticoagulation strategies.