Management of New-Onset Postoperative Atrial Fibrillation Utilizing Insertable Cardiac Monitor Technology to Observe Recurrence of AF (MONITOR-AF)

Background: New-onset postoperative atrial fibrillation (POAF) occurs in up to 30% of patients undergoing coronary artery bypass grafting (CABG). POAF is associated with short- and long-term mortality. Methods: To identify the true incidence and time course of recurrent atrial fibrillation (AF) in patients with POAF, we prospectively assigned 23 patients with POAF to receive an implantable loop recorder (ILR; Medtronic Inc., Minneapolis, MN, USA) for the detection of recurrent AF. Two electrophysiologists independently adjudicated monthly ILR transmissions to classify recurrent AF. We defined AF as any episode lasting ≥6 minutes. Results: The cohort included 23 subjects averaging 69.1 ± 7.2 years of age. Their mean CHADS₂ score averaged 1.9 ± 0.8. Note that 26.1% underwent direct current cardioversion prior to discharge; 95.7% left the hospital taking amiodarone and 26.1% warfarin. A total of 14 patients (60.9%) experienced recurrent AF. AF first recurred within 3 months in nine patients (39.1%), and in 10 patients AF emerged or continued beyond 3 months. Eight of 17 (47.1%) patients followed for at least 1 year experienced AF recurrence beyond 1 year of CABG. The time from surgery to first AF episode averaged 143 ± 22.5 days. Long-term monitoring shows that 60.9% of patients with POAF develop recurrent AF. Conclusion: POAF may represent a propensity for recurrent paroxysmal atrial fibrillation, and not simply a transient consequence of postoperative stress and inflammation. Better detection of recurrent AF might identify patients at risk for stroke who would benefit from continuing anticoagulation.