Cardiac structure, function and coronary anatomy 10 years after isolated contemporary adjuvant radiotherapy in breast cancer patients with low cardiovascular baseline risk.

Abstract

The effects of isolated contemporary low-dose breast cancer (BC) radiotherapy (RT) on the heart remain poorly understood. To assess the long-term impacts of BC-RT on cardiac structure and function. 76 women (62 ± 7 years) without history of prior heart disease, who had undergone RT for either first left (n = 36) or right (n = 40) BC, without additional medical oncology therapy apart from hormonal treatment 11 ± 1 years earlier, underwent transthoracic echocardiography, cardiac MRI (CMR), Coronary CT (CTCA), NT-pro BNP, and a 6-minute walk test (6MWT). They were compared to 54 age-matched healthy female controls. By CTCA 68% of BC patients exhibited no or very mild coronary disease, while only 11% had moderate stenosis (50-69%) and 3% had significant stenosis (>70%). Despite slightly reduced regional echocardiographic midventricular strains, BC patients exhibited similar global left and right ventricular volumes, ejection fractions, and global strains by echocardiography and CMR as controls. Mitral E/e' ratios were slightly higher, and mitral deceleration times were slightly lower, but NT-proBNP was similar to controls. Also, 6MWT was normal. None had late gadolinium enhancement, and extracellular volume fraction was similar in BC (28 ± 3 vs 29 ± 3, p = 0.15) and controls. No differences were observed relative to dose or side of RT. Aside from minor alterations of regional strains and diastolic parameters, women who received isolated RT for BC had low prevalence of coronary disease, normal global systolic function, NT-pro BNP and exercise capacity and showed no structural changes by CMR, refuting significant long-term cardiotoxicity in such low-risk patients.