Low Atrial Fibrillation Burden After CABG Challenges Need for Long-Term Anticoagulation: JAMA
Germany: Researchers have found in a new study that while the incidence of new-onset atrial fibrillation (AF) after coronary artery bypass grafting (CABG) is higher than previously reported, the overall AF burden is minimal, particularly beyond the first 30 days. These findings raise questions about current guideline recommendations for long-term oral anticoagulation in post-CABG patients with new-onset AF.
The study, published in JAMA by Dr. Florian E. M. Herrmann and colleagues from the Department of Cardiac Surgery, LMU University Hospital, Munich, Germany, evaluated 198 patients undergoing CABG who received insertable cardiac monitors (ICMs) for continuous long-term heart rhythm monitoring. Participants had three-vessel or left main coronary artery disease, no prior history of arrhythmias, and were followed for one year to assess the occurrence and burden of AF.
Key Findings:
- Nearly half of the patients (48%) developed new-onset atrial fibrillation (AF) within one year after coronary artery bypass grafting.
- The median AF burden during the first year was 0.07%, approximately 370 minutes in total.
- AF episodes were most significant in the first week after surgery, with a median burden of 3.65%.
- Between days 8 and 30, the median AF burden declined sharply to 0.04%.
- From day 31 onward, the median AF burden was effectively 0%.
- Only three patients experienced AF episodes lasting longer than 24 hours after discharge.
- Most AF events post-CABG were subclinical and of short duration.
The findings suggest that while AF after CABG is common, its clinical impact may be limited due to the very low burden, particularly after the first month. Current North American guidelines recommend considering 60 days of oral anticoagulation for new-onset AF post-CABG, a moderate-strength recommendation based on nonrandomized studies. However, the present study’s data indicate that the routine use of long-term anticoagulation may not be necessary for most patients, especially given the short and often asymptomatic nature of post-CABG AF.
The study’s strengths include continuous, meticulous monitoring with ICMs, providing detailed insights into AF patterns over time. Nevertheless, several limitations were noted. Episodes shorter than two minutes may have gone undetected, and the small sample size and selective patient population limit generalizability. The study focused on elective CABG patients with preserved left ventricular function and did not assess the efficacy or safety of anticoagulation in this setting. Additionally, continuous monitoring in guiding anticoagulation decisions remains undetermined.
"The study demonstrates that although new-onset AF after CABG is more frequent than previously believed, the overall burden is extremely low, especially after 30 days post-surgery. AF episodes lasting 24 hours or longer are rare, and most occurrences are subclinical," the authors wrote.
These findings challenge existing recommendations for prolonged oral anticoagulation in post-CABG patients with new-onset AF, suggesting that treatment strategies may need to be reassessed. The authors recommend reevaluating the need for anticoagulation 30 days after surgery, potentially sparing many patients from unnecessary long-term therapy while still maintaining safety.
Reference:
Herrmann FEM, Jeppsson A, Kirov H, et al. Long-Term Continuous Monitoring of New-Onset Atrial Fibrillation After Coronary Artery Bypass Grafting. JAMA. Published online October 09, 2025. doi:10.1001/jama.2025.14891
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