Background It is unclear whether new‐onset postoperative atrial fibrillation (POAF) early after coronary artery bypass grafting (CABG) is associated with a similar risk of adverse outcomes as new‐onset atrial fibrillation occurring later after CABG. Methods All patients treated with CABG in Sweden from 2007 to 2020 were investigated. Individual patient data from SWEDEHEART (Swedish Web System for Enhancement and Development of Evidence‐Based Care in Heart Disease Evaluated According to Recommended Therapies) registry and 3 other prospective national registries were merged. The adjusted incidences of all‐cause mortality, ischemic stroke, any thromboembolism, heart failure hospitalization, and major bleeding within 12 months after debut of POAF (AF occurring before hospital discharge) or Late AF (new‐onset AF occurring between 3 months and 3 years after CABG) were compared by multivariable Poisson regression analysis, adjusted for time‐updated patient characteristics and comorbidities. Results Out of 35 329 patients, 10 609 (30.0%) developed POAF and 628 (2.5%) developed Late AF. The crude mortality rate was lower in patients with POAF than in patients with Late AF (1.88 95% CI, 1.63–2.17 versus 9.08 95% CI, 6.92–11.82 per 100 patient‐years). The adjusted incidence rate ratios for all‐cause mortality (2.91 95% CI, 2.10–3.95); ischemic stroke (1.70 95% CI, 1.15–2.44); any thromboembolism (1.59 95% CI, 1.11–2.22), heart failure hospitalization (1.61 95% CI, 1.19–2.12); and major bleeding (1.73 95% CI, 1.24–2.36) were higher in patients with Late AF. Conclusions POAF was associated with a markedly lower risk for morbidity and mortality than late new‐onset AF after CABG. POAF and late new‐onset AF after CABG are 2 different clinical entities of AF that may require different treatment strategies.
Herrmann et al. (2025) studied this question.