Association of Sinoatrial Node Radiation Dose with Atrial Fibrillation and Mortality in Patients with Lung Cancer

Abstract

Importance: Atrial fibrillation (AF) can develop following thoracic irradiation. However, the critical cardiac substructure responsible for AF has not been properly studied. Objective: To describe the incidence of AF in patients with lung cancer and determine predictive cardiac dosimetric parameters. Design, Setting, and Participants: This retrospective cohort study was performed at a single referral center and included 239 patients diagnosed with limited-stage small cell lung cancer (SCLC) and 321 patients diagnosed with locally advanced non-small cell lung cancer (NSCLC) between August 2008 and December 2019 who were treated with definitive chemoradiotherapy. Exposures: Radiation dose exposure to cardiac substructures, including the chambers, coronary arteries, and cardiac conduction nodes, were calculated for each patient. Main Outcomes and Measures: Main outcomes were AF and overall survival. Results: Of the 239 and 321 patients with SCLC and NSCLC, the median (IQR) age was 68 (60-73) years and 67 (61-75) years, and 207 (86.6%) and 261 (81.3%) were men, respectively. At a median (IQR) follow-up time of 32.7 (22.1-56.6) months, 9 and 17 patients experienced new-onset AF in the SCLC and NSCLC cohorts, respectively. The maximum dose delivered to the sinoatrial node (SAN Dmax) exhibited the highest predictive value for prediction of AF. A higher SAN Dmaxsignificantly predicted an increased risk of AF in patients with SCLC (adjusted hazard ratio [aHR], 14.91; 95% CI, 4.00-55.56; P