How to prevent and manage radiation-induced coronary artery disease

Radiation-induced coronary heart disease (RICHD) is the second most common cause of morbidity and mortality in patients treated with radiotherapy for breast cancer, Hodgkin's lymphoma and other prevalent mediastinal malignancies. The risk of RICHD increases with radiation dose. Exposed patients may present decades after treatment with manifestations ranging from asymptomatic myocardial perfusion defects to ostial, triple-vessel disease and sudden cardiac death. RICHD is insidious, with a long latency and a tendency to remain silent late into the disease course. Vessel involvement is often diffuse and is preferentially proximal. The pathophysiology is similar to that of accelerated atherosclerosis, characterised by the formation of inflammatory plaque with high collagen and fibrin content. The presence of conventional risk factors potentiates RICHD, and aggressive risk factor management should ideally be initiated prior to radiation therapy. Stress echocardiography is more sensitive and specific than myocardial perfusion imaging in the detection of RICHD, and CT coronary angiography shows promise in risk stratification. Coronary artery bypass grafting is associated with higher risks of graft failure, perioperative complications and all-cause mortality in patients with RICHD. In most cases, the use of drug-eluting stents is preferable to surgical intervention, bare metal stenting or balloon-angioplasty alone.

Novel concepts in radiation-induced cardiovascular disease

Radiation-induced cardiovascular disease (RICVD) is the most common nonmalignant cause of morbidity and mortality among cancer survivors who have undergone mediastinal radiation therapy (RT). Cardiovascular complications include effusive or constrictive pericarditis, cardiomyopathy, valvular heart disease, and coronary/vascular disease. These are pathophysiologically distinct disease entities whose prevalence varies depending on the timing and extent of radiation exposure to the heart and great vessels. Although refinements in RT dosimetry and shielding will inevitably limit future cases of RICVD, the increasing number of long-term cancer survivors, including those treated with older higher-dose RT regimens, will ensure a steady flow of afflicted patients for the foreseeable future. Thus, there is a pressing need for enhanced understanding of the disease mechanisms, and improved detection methods and treatment strategies. Newly characterized mechanisms responsible for the establishment of chronic fibrosis, such as oxidative stress, inflammation and epigenetic modifications, are discussed and linked to potential treatments currently under study. Novel imaging modalities may serve as powerful screening tools in RICVD, and recent research and expert opinion advocating their use is introduced. Data arguing for the aggressive use of percutaneous interventions, such as transcutaneous valve replacement and drug-eluting stents, are examined and considered in the context of prior therapeutic approaches. RICVD and its treatment options are the subject of a rich and dynamic body of research, and patients who are at risk or suffering from this disease will benefit from the care of physicians with specialty expertise in the emerging field of cardio-oncology.