Long-Term Continuous Monitoring of New-Onset Atrial Fibrillation After Coronary Artery Bypass Grafting

Importance: The incidence and burden of new-onset atrial fibrillation (AF) after coronary artery bypass grafting (CABG) are not known. Nevertheless, North American guidelines state that it is reasonable to administer 60 days of oral anticoagulation to patients with new-onset AF after CABG, a moderate-strength recommendation (class 2a) based on evidence derived from nonrandomized clinical studies. Objective: To test the hypothesis that the incidence of new-onset AF within the first year after CABG is higher than suggested in the current literature and to assess AF burden. Design, Setting, and Participants: A prospective, multicenter cohort study in 2 academic cardiac surgery centers in Germany that involved 198 patients with 3-vessel coronary artery disease or left main disease and no history of arrhythmias who received an insertable cardiac monitor during CABG for long-term continuous electrocardiographic monitoring. Patients were enrolled from November 2019 through November 2023 and were followed up for 1 year. Exposures: Atrial fibrillation detected within a year of continuous monitoring using insertable cardiac monitors implanted during CABG. Main Outcomes and Measures: Cumulative incidence of new-onset AF within a year of surgery. Secondary outcomes were AF burden and clinical outcomes. Results: A total of 1217 patients were assessed, and 1008 were excluded. Of the 198 patients enrolled (173 male 87.4%; 25 female 12.6%; mean age, 66 SD, 9 years), 95 patients developed new-onset AF within the first year after CABG (cumulative incidence, 48%; 95% CI, 41%-55%). The median AF burden during the first year was 0.07% (IQR, 0.02%-0.23%) or 370 minutes. The median AF burden on days 1 through 7 was 3.65% (IQR, 0.95%-9.09%); on days 8 through 30, 0.04% (IQR, 0%-1.21%); and on days 31 through 365, 0% (IQR, 0%-0.0003%), corresponding to 368, 13, and 0 minutes, respectively. After discharge, 3 patients had an AF episode longer than 24 hours. Conclusions and Relevance: Although the incidence of new-onset AF after CABG in this study was higher than previously reported, the AF burden in these patients was very low, especially after 30 days. The very low AF burden questions the current guideline recommendations that long-term oral anticoagulation should be considered in patients with new-onset AF after CABG.