New‐Onset Atrial Fibrillation After Coronary Artery Bypass Graft and Long‐Term Risk of Stroke: A Meta‐Analysis

BACKGROUND: New‐onset atrial fibrillation (NOAF) after coronary artery bypass graft is related to an increased short‐term risk of stroke and mortality. We investigated whether the long‐term risk of stroke is increased. METHODS AND RESULTS: We performed a systematic review and meta‐analysis of studies that included patients who had coronary artery bypass graft and who afterwards developed NOAF during their index admission; these patients did not have previous atrial fibrillation. The primary outcome was risk of stroke at 6 months or more in patients who developed NOAF compared with those who did not. Odds ratios, relative risk, and hazard ratios were considered equivalent; outcomes were pooled on the log‐ratio scale using a random‐effects model and reported as exponentiated effect‐sizes. We included 16 studies, comprising 108 711 participants with a median follow‐up period of 2.05 years. Average participant age was 66.8 years, with studies including an average of 74.8% males. There was an increased long‐term risk of stroke in the presence of NOAF (unadjusted studies effect‐sizes=1.36, 95% confidence interval, 1.12–1.65, P=0.001, adjusted studies effect‐sizes=1.25, 95% confidence interval, 1.09–1.42, P=0.001). There was evidence of moderate effect variation because of heterogeneity in studies reporting unadjusted (P=0.021, I(2)=49.8%) and adjusted data (P=0.081, I(2)=49.1%), and publication bias in the latter group (Egger's test, P=0.031). Sensitivity analysis on unadjusted data by study quality, design, and surgery did not alter the effect direction. CONCLUSIONS: Presence of NOAF in patients post–coronary artery bypass graft is associated with increased long‐term risk of stroke compared with patients without NOAF. Further studies may show whether the increased risk is mediated by atrial fibrillation and whether anticoagulation reduces risk.