This prospective observational cohort study aims to assess the risk of radiation-induced cardiotoxicity in patients undergoing thoracic radiotherapy by integrating real-time arrhythmia monitoring using wearable cardiac rehabilitation (wearable CR) devices and AI-based cardiac substructure segmentation. The study will analyze radiation dose exposure to key cardiac structures, including the sinoatrial node (SAN) and pulmonary veins (PV), to identify risk factors for atrial fibrillation (AF) and other arrhythmias. Patients will receive wearable CR monitoring at 3, 12, and 24 months post-radiotherapy, with cardiology follow-up and intervention based on standard clinical guidelines. The study will recruit 111 patients over three years, with a two-year follow-up after radiotherapy. The primary endpoint is the incidence of grade 3+ AF within 2 years, with secondary outcomes including any-grade arrhythmia rates, arrhythmia burden, and survival analysis. By establishing a prospective thoracic radiotherapy patient cohort, this study aims to identify dose-related risk factors, improve early detection and management of radiation-induced arrhythmias, and provide evidence-based strategies to enhance treatment safety and efficacy.

"This prospective observational cohort study aims to assess the risk of radiation-induced arrhythmias in patients undergoing thoracic radiotherapy for solid tumors, integrating real-time cardiac monitoring with wearable cardiac rhythm (Wearable CR) devices and AI-based cardiac substructure segmentation. The study will recruit 111 patients over three years, with a two-year follow-up post-radiotherapy. Patients will undergo Wearable CR monitoring at 3, 12, and 24 months, facilitating early detection and intervention based on standard cardiology guidelines. Radiation dose exposure to key cardiac structures, including the sinoatrial node (SAN) and pulmonary veins (PV), will be analyzed to evaluate correlations with atrial fibrillation (AF) and other arrhythmias. AI-driven segmentation will aid in optimizing dose distribution to minimize cardiotoxicity while maintaining treatment efficacy. The primary endpoint is the incidence of grade 3+ AF within 2 years, with secondary endpoints including any-grade arrhythmia rates, arrhythmia burden, and survival outcomes. All enrolled patients will receive standard radiotherapy protocols tailored to their respective cancer types, ensuring treatment consistency while assessing the impact of radiation on any kinds of cardiotoxicities.

Inclusion Criteria:

• Patients with solid tumors requiring thoracic radiotherapy
• Undergoing curative-intent radiotherapy
• Expected survival > 4 months
• Adults aged ≥ 20 years
• ECOG performance status 0-2
• Classified as moderate-to-high risk for radiation-induced cardiotoxicity per the 2022 ESC guidelines
• Able to read, understand, and sign the informed consent form

Exclusion Criteria:

• History of prior thoracic radiotherapy
• Inability to provide informed consent or refusal to participate
• Pre-existing arrhythmia diagnosed through medical history or pre-treatment evaluation
• Expected survival ≤ 4 months
• Classified as low risk for radiation-induced cardiotoxicity per the 2022 ESC guidelines
• Unsuitability for Wearable CR device use

Patients undergoing thoracic radiotherapy for solid tumors with curative intent, aged ≥ 20 years, ECOG 0-2, and at moderate-to-high risk for radiation-induced cardiotoxicity per ESC 2022 guidelines.