Abstract PS1-07-08: Association of Prior Thoracic Radiation with Clinical Outcomes in Patients Hospitalized for Atrial Tachyarrhythmias

Abstract Introduction: Thoracic radiation therapy (TRT) is frequently utilized in the management of malignancies such as breast cancer, lymphoma, and lung cancer. While its cardiotoxic effects—particularly coronary artery disease—are well described, less is known about the long-term impact of TRT on arrhythmia-related hospitalizations. This is particularly relevant given the growing population of cancer survivors at risk for cardiovascular disease. Atrial fibrillation and flutter are among the most common sustained arrhythmias in this population, yet outcomes in patients with prior TRT remain poorly characterized. This study examines whether a history of thoracic radiation influences outcomes among patients hospitalized and admitted with atrial fibrillation or flutter. Methods: A retrospective cohort study was conducted using data from the National Inpatient Sample (2016-2022). Atrial tachyarrhythmia hospitalizations were identified using ICD-10 codes for atrial fibrillation and atrial flutter, which likely reflect cases of new-onset arrhythmia or rate-related decompensation. Patients with prior thoracic radiation were identified using corresponding diagnosis codes. Due to coding limitations, atrial tachycardias such as multifocal atrial tachycardia (MAT) and focal atrial tachycardia could not be reliably identified and were therefore excluded—an acknowledged limitation of this study. Multivariable logistic regression was used to calculate adjusted odds ratios (aORs) for binary outcomes, and linear regression was used for continuous outcomes. The primary endpoint was in-hospital mortality; secondary endpoints included total hospitalization charges and length of stay (LOS). Results: Among 3,198,304 patients hospitalized primarily for atrial tachyarrhythmias, 8,570 had a documented history of thoracic radiation. The mean age in the TRT group was 72.5 ± 6.21 years, with 52.9% identifying as male. Prior TRT was associated with a significantly elevated risk of in-hospital mortality (aOR 1.75; 95% CI: 1.27-2.40; p=0.001). Interestingly, these patients had significantly lower total hospital charges (-$9,356; 95% CI: -11,893 to -6,818; p