Radiotherapy-induced right ventricular remodelling: The missing piece of the puzzle.

The number of studies demonstrating that right ventricular structure, function and mechanics are valuable predictors of cardiovascular and total morbidity and mortality in patients with a wide range of cardiovascular conditions is constantly increasing. Most studies that evaluated the influence of radiotherapy on the heart focused on left ventricular remodelling, which is why current guidelines only recommend detailed assessment of the left ventricle. Data regarding right ventricular changes in cancer patients treated with radiotherapy are scarce. Given that radiotherapy more often induces late cardiac impairment - unlike chemotherapy-induced cardiotoxicity, which is usually acute - it is quite reasonable to follow these patients echocardiographically for a long time (even for 20years after initiation of radiotherapy). Investigations that have followed cancer survivors for at least 10years after radiotherapy agree that right ventricular structure, systolic/diastolic function and mechanics are significantly impaired. The mechanisms of radiation-induced right ventricular remodelling are still unclear, but it is thought that fibrosis is the dominant factor in myocardial remodelling and vascular changes. Many factors may contribute to right ventricular impairment during and after radiotherapy: cumulative radiation dose; dose per treatment; delivery technique; radiation target (chest and mediastinum); and co-morbidities. In this review, we aim to provide a comprehensive overview of the potential mechanisms of radiation-induced right ventricular remodelling, and to summarize clinical studies involving radiotherapy-treated cancer patients.