The Society of Thoracic Surgeons 2026 Clinical Practice Guidelines for the Prevention and Treatment of New-Onset Postoperative Atrial Fibrillation after Cardiac Surgery

BACKGROUND: Postoperative atrial fibrillation (POAF) is the most frequent complication after cardiac surgery and is associated with greater morbidity, mortality, length of stay, and cost. Multiple pharmacologic and procedural strategies exist for POAF prevention and treatment, yet practice variation persists. The Society of Thoracic Surgeons (STS) Workforce on Evidence-Based Surgery convened a multidisciplinary writing group to synthesize contemporary evidence and develop guideline recommendations for preventing and treating new-onset POAF after cardiac surgery. METHODS: In 2025, the group used the Population, Intervention, Comparison, Outcome framework to formulate clinical questions spanning preoperative, intraoperative, and postoperative domains. Following standardized STS methodology, evidence from randomized controlled trials and observational studies was reviewed, and recommendations were graded by Class of Recommendation and Level of Evidence. RESULTS: Fifteen recommendations were developed: 8 addressing preventive strategies, 3 intraoperative techniques, and 4 postoperative treatments. Two Class I recommendations addressed perioperative oral amiodarone and rhythm cardioversion for hemodynamically unstable POAF. Two Class IIa recommendations supported posterior pericardiotomy and perioperative beta-blockers. Eight Class IIb recommendations reflected areas of uncertainty and limited data. Three Class III recommendations addressed therapies without demonstrated benefit. CONCLUSIONS: Levels of evidence vary across interventions, and high-quality data remain limited for POAF after cardiac surgery. Pharmacologic studies often lack granularity in dose and timing, and intraoperative maneuvers continue to evolve. Individualized risk assessment remains essential given therapy-related side effects. The 2026 STS guidelines provide the most comprehensive recommendations focused on postoperative atrial fibrillation after cardiac surgery, offering a framework to standardize care and highlight future investigational priorities.