Researchers, led by Kyung Hwan Kim, MD, PhD, sought to determine the incidence of atrial fibrillation following thoracic irradiation in patients with lung cancer, as well as potential predictive cardiovascular risk factors. In their study, published in JAMA Oncology, the authors reported that incidental irradiation of the sinoatrial node (SAN) could drive development of atrial fibrillation and increased mortality.
This retrospective, single-center cohort study included 239 patients with limited-stage small cell lung cancer (SCLC) and 321 patients with locally advanced non-small cell lung cancer (NSCLC) who received definitive chemoradiotherapy between August 2008 and December 2019. Each patient was assessed for radiation exposure in cardiac substructures, atrial fibrillation, and survival.
Sinoatrial Node Irradiation Linked to Atrial Fibrillation Development
The SCLC and NSCLC groups had a median age of 68 years (interquartile range [IQR], 60–73) and 67 years (IQR, 61–75), and were 86.6% and 81.3% male, respectively. At a median follow-up of 32.7 months (IQR, 22.1–56.6), 9 patients in the LSCL group and 17 patients in the NSCLC group had developed new-onset atrial fibrillation.
According to the authors, the factor with the highest predictive was maximum radiation dose delivered to the SAN, and a higher maximum dose significantly predicted increased atrial fibrillation risk in patients with both SCLC (adjusted hazard ratio [HR], 14.91; 95% confidence interval [CI], 4.00–55.56; P<.001) and NSCLC (aHR, 15.67; 95% CI, 2.08–118.20; P=.008).
An increased maximum SAN dose was also associated with poor overall survival for the SCLC (aHR, 2.68; 95% CI, 1.53–4.71; P<.001) and NSCLC (aHR, 1.97; 95% CI, 1.45–2.68; P<.001) cohorts; however, the authors did not find a link between an increased dose and non-atrial fibrillation-related cardiac events.
In closing, the authors suggested healthcare providers consider “the need to minimize radiation dose exposure to the SAN during radiotherapy planning and to consider close follow-up for the early detection of atrial fibrillation in patients receiving thoracic irradiation.”