Whole Heart Dose Parameters Predict Severe Arrhythmias After Neoadjuvant Chemoradiotherapy for Esophageal Squamous Cell Cancer: A Competing Risk Analysis of 358 Patients

ABSTRACT Background Dose exposure to supraventricular cardiac conduction system doses has been reported to be associated with distinct arrhythmia classes after thoracic radiotherapy, but its impact in esophageal squamous cell carcinoma (ESCC) remains unknown. Materials and Methods Locally advanced ESCC treated with neoadjuvant chemoradiotherapy (nCRT) were included. The primary endpoint was grade ≥ 3 adverse cardiac arrhythmia events. Prediction performance was evaluated through time‐dependent receiver operating characteristic curves, and competing risk frameworks were implemented to quantify the cumulative incidence of distinct cardiac arrhythmia. Results Of 358 patients, 84.9% were men, with a median age of 66 years (range: 39–79 years). A total of 60 (16.8%) patients experienced at least 1 grade ≥ 3 arrhythmia, with a median time to first arrhythmia of 13 months (95% CI: 12–15 months). The 2‐year cumulative incidences of distinct cardiac arrhythmia were 8.89% for AF, 2.96% for atrial flutter, and 5.12% for other SVT. Baseline coronary heart disease was a risk factor for all types of arrhythmia ( p < 0.05). After adjusting for baseline cardiovascular risk factors, Heart D max (sHR 3.69, p = 0.0024) was associated with AF, Heart volume receiving 5 Gy with atrial flutter (sHR: 9.35, p = 0.0077), and Heart volume receiving 40 Gy (sHR 5.72, p = 0.00078) with other SVT. Conclusion Grade ≥ 3 cardiac arrhythmia associated with thoracic radiation occurs in 16.7% of ESCC patients undergoing nCRT within a median time of 13 months. The radiation dose exposure of the supraventricular cardiac conduction system is not associated with increased cardiac arrhythmia. Specific arrhythmia subtypes exhibited differential associations with distinct dose‐volume parameters of whole heart irradiation.