The link between atrial fibrosis and postoperative atrial fibrillation after cardiac surgery: A systematic review

Postoperative atrial fibrillation (POAF) is a common complication that can affect up to 20-44% of patients undergoing cardiac surgery. Evidence suggests that atrial fibrosis is a key factor in the development of POAF due to the disruption of the myocardial electric properties. This systematic review examines the correlation between pre-existing atrial fibrosis and the development of POAF after cardiac surgery. A systematic literature search was conducted in MEDLINE, Embase, and Google Scholar (2000 to March 2025) to identify studies that conducted comparative analysis of atrial fibrosis levels between those who did and did not develop POAF, using histological assessment methods. Extracted data, included study characteristics, histopathological staining methods and analysis findings, fibrosis quantification methods, and overall POAF incidence. Thirteen studies met the inclusion criteria, resulting in a total of 1222 patients, primarily undergoing coronary artery bypass surgery. The incidence of POAF ranged from 14%-42.4% (median 31.6%). In more than half of the studies (7/13), patients who developed POAF demonstrated statistically significant higher degrees of atrial fibrosis compared to those that remained in sinus rhythm postoperatively (four exhibited p < 0.001). Of the eight studies that conducted multivariate analyses, three identified atrial fibrosis as an independent POAF predictor. High heterogeneity precluded pooling of results into a meta-analysis. The current evidence examining the link between pre-existing atrial fibrosis and the development of POAF is restricted by methodological heterogeneity and inconsistent findings. Further efforts to standardize fibrosis quantification methods and POAF definitions are warranted before histopathological assessments can reliably inform POAF risk before cardiac surgery.