Radiation and the heart: systematic review of dosimetry and cardiac endpoints

Recent trials in radiotherapy have associated heart dose and survival, inadequately explained by the existing literature for radiation-related late cardiac effects.  Authors aimed to review the recent literature on cardiac dosimetry and survival/cardiac endpoints. Areas covered: Systematic review of the literature in the past 10 years (2008-2017) was performed to identify manuscripts reporting both cardiac dosimetry and survival/cardiac endpoints.  Authors identified 64 manuscripts for inclusion, covering pediatrics, breast cancer, lung cancer, gastrointestinal diseases (primarily esophageal cancer), and adult lymphoma. Expert commentary: In the first years after radiotherapy, high doses (>40 Gy) to small volumes of the heart are associated with decreased survival from an unknown cause.  In the long-term, mean heart dose is associated with a small increased absolute risk of cardiac death.  For coronary disease, relative risk increases roughly 10% per Gy mean heart dose, augmented by age and cardiac risk factors.  For valvular disease and heart failure, doses >15 Gy substantially increase risk, augmented by anthracyclines.  Arrhythmias after radiotherapy are poorly described but may account for the association between upper heart dose and survival.  Symptomatic pericardial effusion typically occurs with doses >40 Gy.  Close follow-up and mitigation of cardiovascular risk factors are necessary after thoracic radiotherapy.