Recurrence of atrial fibrillation after cardiac surgery: Long-term evidence from cardiac devices

Tim Swinn^1,2*Marius Pezard-Snell³Lauren Brain⁴Gerasimos Dimitropoulos⁵Amardeep Dastidar⁶Eva Sammut^2,3Palash Barman³

• ¹North Bristol NHS Trust, Bristol, United Kingdom
• ²University of Bristol, Bristol, United Kingdom
• ³Bristol Heart Institute, Bristol, United Kingdom
• ⁴Royal United Hospitals Bath NHS Foundation Trust, Bath, United Kingdom
• ⁵Royal Devon and Exeter Hospital, Exeter, United Kingdom
• ⁶NHS North Bristol NHS Trust, Bristol, United Kingdom

Atrial fibrillation after cardiac surgery occurs in 20-40% of cases and is associated with significant morbidity. Studies have shown an association with immediate post-operative atrial fibrillation and recurrent atrial fibrillation however we are not aware of any trials using continuous electrogram monitoring data from cardiac devices (pacemakers or defibrillators) to assess rate of long-term atrial fibrillation recurrence. Using institutional databases, we identified patients with a cardiac device who underwent coronary artery bypass grafting and/or a procedure on their aortic valve or mitral valve between January 2011 and March 2020. Post-operative atrial fibrillation and comorbidities were assessed using the electronic patient record and recurrent device-detected atrial fibrillation was defined as any episode of atrial fibrillation lasting greater than 6 minutes on device check between 6 weeks and 18 months post-operatively. Post-operative atrial fibrillation was associated with recurrent device-detected atrial fibrillation (n = 85, odds ratio 3.26, 95% confidence interval 1.19-8.97, p = 0.02). Age was an independent risk factor for developing post-operative atrial fibrillation (n = 302, p = 0.033) and mitral valve surgery had a higher rate of post-operative atrial fibrillation than coronary artery bypass grafting alone (54% vs. 32%, p = 0.047) and aortic valve surgery (54% vs. 34%, p = 0.048). 44% of patients developing postoperative atrial fibrillation were discharged on oral anticoagulation. Post-operative is associated with threefold greater odds of developing recurrent device-detected atrial fibrillation: it is not a simply transient phenomenon. Larger prospective studies are required to identify which patients would benefit from surveillance of heart rhythm and whether oral anticoagulation is an effective treatment in this patient group.