Radiotherapy-induced changes in right ventricular function in patients with early-stage breast cancer

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Finnish state research funding for university-level health research Background In breast cancer patient’s adjuvant RT nearly doubles cardiac mortality, and in some subgroups long-term cardiovascular mortality exceeds cancer mortality. The effects of RT on left ventricle are well established, but studies concerning right ventricular (RV) changes are sparse. Methods The study population consisted of 31 patients with early-stage left-sided breast cancer who had undergone adjuvant therapy using modern RT delivery techniques. Echocardiographic examinations including right ventricular (RV) strain analysis were performed prior to the RT, immediately after, as well as three and six years after the RT. In addition, the patients underwent cardiac magnetic resonance (CRM) imaging at six-year control. Results The mean RT dose to the RV free wall was 5.75±2.49 Gy. In echocardiography, basal early diastolic strain rate increased from 1.8±0.8 1/s to 2.3±0.9 1/s (p = 0.045), and the ratio of tricuspid inflow e and a-waves declined from 1.3±0.2 to 1.1±3.0 (p = 0.035), but there were no changes in global or regional strain or strain values in the six-year follow-up. In addition, In CMR imaging, the global circumferential strain values were associated with RV free wall RT dose (p = 0.005) with each mean Gy inducing 0.395% reduction in the circumferential strain [95% CI; −0.658, −0.120] whereas longitudinal strain was not associated with the RT dose. Conclusions Modern conformal breast cancer RT did not influence RV systolic function or result in clinically meaningful cardiac sequelae during six-year follow-up. Minor changes in RV diastolic function and the association between circumferential strain in CRM and the RT dose indicate that these parameters might be more sensitive in detecting RT-induced cardiac changes.