Increased C-reactive protein is associated with the severity of thoracic radiotherapy-induced cardiomyopathy

Irradiation of the heart during cancer radiotherapy is associated with a dose-dependent risk of heart failure. Animal studies have demonstrated that irradiation leads to an inflammatory response within the heart as well as a reduction in cardiac reserve. In the current study we aimed to evaluate whether inflammatory biomarkers correlated with changes in cardiac function and reserve after radiotherapy for breast or lung cancer.

We studied 25 subjects with a history of breast or lung cancer without a prior diagnosis of cardiovascular disease or heart failure, 1.8 years [0.4-3.6] post-radiotherapy involving at least 5 Gray (Gy) to at least 10% of the heart. High-sensitivity C-reactive protein (CRP) was abnormal (≥2 mg/L) in 16 (64%) subjects. Cardiac function and reserve was measured with Doppler echocardiography before and after exercise and defined as left-ventricular ejection fraction (LVEF), early diastolic mitral annulus velocity (e'), and increase in LV outflow tract velocity time integral cardiac output (cardiac reserve) with exercise. Subjects with abnormal CRP had significantly lower LVEF (51 [44-59] % vs 61 [52-64] %, P = 0.039), lower e' (7.4 [6.6-7.9] cm/sec vs 9.9 [8.3-12.0] cm/sec, P = 0.010), and smaller cardiac reserve (+ 1.5 [1.2-1.7] L/min vs + 1.9 [1.7-2.2] L/min, P = 0.024).

Elevated systemic inflammation is associated with impaired left-ventricular systolic and diastolic function both at rest and during exercise in subjects who have received radiotherapy with significant incidental heart dose for the treatment of cancer.