Impact of Atrial Fibrillation on Hospital Outcomes in NSTEMI Patients: A Retrospective Cohort Study

Atrial fibrillation (AF) is the most common sustained arrhythmia and frequently occurs in patients with acute coronary syndromes (ACS). Non-ST elevation myocardial infarction (NSTEMI) accounts for nearly 70% of ACS hospitalizations and poses significant morbidity and healthcare burden. Despite its prevalence, the impact of AF on in-hospital outcomes in NSTEMI remains underrecognized, and current risk models often exclude AF. MethodsWe conducted a retrospective cohort study using de-identified patient-level data from HCA Healthcare, capturing 31,649 NSTEMI admissions across 180 U.S. hospitals (2021-2022). Patients were stratified based on coronary artery bypass grafting (CABG) status. Multivariable logistic and linear regression models evaluated associations between AF and in-hospital mortality, 30-day readmission, and length of stay (LOS). ResultsAF was independently associated with worse in-hospital outcomes in both CABG and non-CABG groups. Among CABG patients, AF was linked to increased odds of in-hospital mortality (OR 2.02), 30-day readmission (OR 1.15), and prolonged LOS (OR 1.21). In non-CABG patients, AF was similarly associated with higher odds of mortality (OR 1.89), readmission (OR 1.23), and LOS (OR 1.31) (all p<0.05). Female sex, heart failure, CKD, and COPD were also linked to adverse outcomes. ConclusionIn this large, multicenter cohort, AF was significantly associated with increased in-hospital mortality, readmission, and LOS among NSTEMI patients, irrespective of CABG status. These findings highlight AF as a key clinical factor warranting consideration in NSTEMI management. Future studies should explore mechanisms underlying these associations and identify strategies for risk mitigation in this high-risk population.