Abstract: Radiation-induced heart disease (RIHD) is a form of cardiotoxicity caused by radioactive substances or radiotherapy, and represents a common long-term complication after thoracic malignancy radiotherapy. RIHD onset is insidious, progression is slow, and significantly affects patients’ long-term quality of life. The pathophysiological mechanisms of RIHD involve multiple pathways, including endothelial cell injury, oxidative stress, inflammatory response, and myocardial fibrosis, ultimately leading to pericarditis, coronary artery disease, valvular heart disease, cardiac dysfunction, and conduction abnormalities, etc. Widespread use of immune checkpoint inhibitors (ICIs) in thoracic tumors, especially the combination of radiotherapy and ICIs, has introduced new changes in cardiac risk. This article reviews the epidemiological characteristics of RIHD, potential molecular targets, clinical manifestations, and treatment options. It also summarizes the value of imaging, electrocardiography, and biomarkers in RIHD monitoring, as well as the cardiac risks associated with combined radiotherapy and immunotherapy. Furthermore, multidisciplinary management strategies and preventive approaches are discussed, aiming to provide a reference for individualized management of RIHD patients in clinical practice.