2315 - Associations between Heart Rate Elevation, Tachycardia and Cardiac Substructure Dose in Patients Receiving Chemoradiotherapy for Non-Small Cell Lung Cancer (NSCLC)
Presenter(s)
A. Ajdari1, M. Bobic2, C. Ciausu3, C. V. Guthier4, M. J. Khandekar5, H. Willers5, R. B. Jimenez6, and F. K. Keane5; 1Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 2Massachusetts General Hospital, Boston, MA, 3Brigham and Women's Hospital, Boston, MA, 4Dana-Farber Brigham Cancer Center, Boston, MA, 5Department of Radiation Oncology, Mass General Brigham/ Massachusetts General Hospital, Boston, MA, 6Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA
Purpose/Objective(s): Cardiac toxicity is a well-recognized, but poorly understood complication associated with thoracic radiotherapy (RT). Given the established relationship between resting heart rate (HR) and cardiovascular health in other settings, our objective was to study the incidence and pattern of HR elevation and de-novo tachycardia as an early sign of cardiac injury and evaluate potential dosimetric contributors to development of tachycardia in patients with non-small cell lung cancer (NSCLC) receiving treatment with chemoradiotherapy (CRT) followed by durvalumab.
Materials/Methods: We retrospectively analyzed the records of consecutive patients with locally advanced NSCLC treated with definitive CRT followed by durvalumab between 2017-2022. Serial resting HR (rHR) measurements were collected during CRT and up to 6 months after completion of RT. The change from baseline rHR (?rHR), as well as the incidence, frequency, and timing of recorded episodes of tachycardia (rHR=100 beats-per-minute [bpm]) were characterized longitudinally. Radiation dose to the heart and 17 cardiac substructures were extracted using AI-assisted auto-segmentation. Associations between HR elevation, tachycardia and cardiac substructure dose were evaluated using Wilcoxon rank-sum test, Cox, and logistic regression analysis.
Results:
118 patients were identified. Median follow-up was 26.6 months. Median age was 69.2 years old (range 45.4 – 84.0). Sixty-six patients (56%) had pre-existing coronary heart disease (CHD) and 22 (18.6%) had pre-existing history of arrhythmias. There was a significant increase in median rHR during RT and after RT, from rHR=83±14 at week 1 to 89±14 at week 4 to 94±16 bpm at 1-month post-RT (p<0.0001). 30% of patients (32/ 106) who did not have recorded tachycardia prior to RT had at least one episode of tachycardia (median=2, range=1-11) during RT, with a median HR of 108 (range 100 – 144) bpm. There was a persistent elevation (>1 standard deviation above baseline) in rHR in 61 patients (64%) six months after completion of CRT. The volume of sinoatrial node (SAN) receiving =5Gy and the volume of the pulmonary veins (PV) receiving =5Gy were both significantly associated with HR elevation (SAN: odds ratio [OR]=1.01, 95% CI=1.01-1.03, p=0.01; PV: OR=1.02, 95% CI=1.01-1.03, p=0.04). Patients who experienced at least one episodes of tachycardia during RT had significantly higher V5Gy (43% vs. 73%, p=0.001) and max-dose of SAN (25Gy vs. 37Gy, p=0.03).
Conclusion: Significant and persistent resting HR elevation and development of episodes of tachycardia during CRT were associated with dose to the sinoatrial node and pulmonary veins. Correlation of elevation of resting HR and episodes of tachycardia with clinical endpoints is ongoing.