Delayed cardiac complications of radiotherapy

Delayed cardiac complications of radiotherapy

Radiation damages the vascular endothelium leading to accelerated coronary atherosclerosis. Due to improvement in radiotherapy techniques, radiation associated cardiac damage is lesser with modern techniques. Most cases occur in those who have undergone mediastinal radiation in a younger age for diseases like Hodgkin’s disease for which longer survival gives a chance for long term cardiac issue to manifest. Radiotherapy for breast cancer is another important cause of cardiac complications of radiotherapy. Radiation induced cardiac damage is enhanced with concomitant use of adriamycin based chemotherapy.

Important delayed cardiac complications of radiotherapy

a) Accelerated coronary artery disease, possibly due to radiation exposure to proximal coronary arteries. This is associated with higher incidence and mortality due to myocardial infarction. Exposure to conventional coronary risk factors like smoking, hypertension and dyslipidemia enhances the risk of coronary atherosclerosis, myocardial infarction and sudden death.¹ Many of the radiation associated cardiac manifestations may be asymptomatic and detectable only on routine screening by echocardiography or other modalities.

b) Restrictive cardiomyopathy due to myocardial fibrosis

c) Constrictive pericarditis following radiation has a poorer outcome after pericardiectomy due to the other associated cardiac sequelae of radiation including myocardial fibrosis and coronary artery disease.
(Radiation is one of the conditions which can cause both constriction and restriction; the other condition being cardiac allograft rejection)

d) Cardiac conduction abnormalities

e) Valvular dysfunction – left sided valves are more commonly affected by fibrosis. But regurgitant lesions are more common than stenotic lesions. Mild aortic regurgitation was the commonest lesion diagnosed by echocardiography.

Reference

1. Byrd BF 3rd et al. Cardiac complications of mediastinal radiotherapy. The other side of the coin. J Am Coll Cardiol. 2003;42:750-1.