Work

Circadian patterns of device-detected postoperative atrial fibrillation during 2.5 years of continuous monitoring after cardiac surgery: The RACE V–Tissue Bank Study

Year: 2026

Type: article

Abstract: Background: Postoperative atrial fibrillation (POAF) is common after cardiac surgery. AF in non-surgical patients exhibits distinct circadian patterns (adrenergic/daytime and vagal/nocturnal), but such patterns for new-onset POAF and recurrent AF remain undefined. Objective: This study aimed to characterize circadian AF patterns and relate chronotypes to clinical, biochemical, histological, and outcome features. Methods: Patients undergoing first cardiac surgery, with and without preoperative AF, were continuously monitored for 2.5 years with an implantable loop recorder. Early AF was defined as AF within 30 days. Patients with sustained AF (≥20 episodes) were chronotyped via circular statistics and local regression of episode duration and ventricular rate (Vrate), and classified as adrenergic, vagal, mixed, or non-rhythmic. Preoperative imaging, electrocardiography, biomarkers, and paired atrial histology were compared across chronotypes. Results: Of the 98 patients (71 without and 27 with preoperative AF), 53 (54.1%) developed POAF (3607 episodes). Patients with prior AF showed a morning onset peak, whereas new-onset POAF showed a uniform 24-hour distribution. Of 26 patients with sustained AF, 20 were rhythmic (9 adrenergic, 7 vagal, 4 mixed), and 6 were non-rhythmic; 27 had incidental AF (<20 episodes). Rhythmic AF correlated with larger atrial volumes, prolonged PR intervals, higher bone morphogenetic protein-10 levels, and greater right-atrial endomysial fibrosis and asymmetry, most pronounced in the mixed chronotype. Adrenergic AF was associated with more arrhythmia-related emergency visits and cardioversions. Conclusion: AF after cardiac surgery comprises distinct circadian subtypes. New-onset POAF and recurrent AF display different circadian patterns, and individual chronotypes are associated with varying degrees of atrial remodeling and clinical outcomes.

Source: Heart Rhythm O2

DOI: 10.1016/j.hroo.2026.06.023