Impact of new-onset atrial fibrillation on 12-month outcomes and mortality after esophagectomy.

New-onset atrial fibrillation (NOAF) is a frequent complication after esophagectomy. While associated with adverse short-term outcomes, its longer-term cardiovascular impact remains uncertain. We evaluated associations between NOAF and postoperative cardiovascular and respiratory complications using a large international real-world dataset. We performed a retrospective cohort study using the TriNetX global federated health research network. Adults undergoing esophagectomy were identified using ICD-10, CPT, and SNOMED codes, excluding those with prior atrial fibrillation or flutter. NOAF was defined within 30 days postoperatively. Propensity score matching (1:1) balanced demographics, comorbidities, and medication use. Outcomes were assessed over 12 months using Cox proportional hazards models. We analyzed 1977 matched patients (mean age 67.1 ± 8.7 years; 18% female). Within 0-3 months, NOAF was associated with increased risks of death (HR 2.09, 95% CI 1.62-2.70), heart failure (HR 2.03, 95% CI 1.32-3.11), myocardial infarction (HR 2.35, 95% CI 1.17-4.74), pneumonia (HR 1.80, 95% CI 1.42-2.29), venous thromboembolism (HR 1.76, 95% CI 1.17-2.66), and rehospitalization (HR 2.78, 95% CI 2.42-3.20), with no significant association for stroke. Between 3 and 12 months, elevated risks persisted for death (HR 1.60, 95% CI 1.30-1.98) and heart failure (HR 2.55, 95% CI 1.37-4.73). Across 12 months, NOAF remained associated with death (HR 1.76, 95% CI 1.50-2.07) and heart failure (HR 2.23, 95% CI 1.56-3.19). NOAF after esophagectomy identifies patients at increased risk of major postoperative and cardiovascular complications, particularly early after surgery.