Changes in left ventricular strain and cardiac biomarkers in a six-year prospective follow-up after breast cancer radiotherapy

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Finnish public grant Aims Breast cancer radiotherapy (RT) can lead to slowly developing cardiac dysfunction and increased incidence of heart failure with preserved ejection fraction (HFpEF). In fact, the risk for HFpEF is shown to be 16-fold after chest radiotherapy. We aimed to study the changes in left ventricular strain six years after radiotherapy as well as changes in cardiac biomarkers during the follow-up. Methods Early left-sided breast cancer patients (n=31) were prospectively followed-up for six years after RT. Left ventricular strain analysis and pro-brain natriuretic peptide (proBNP) tests were performed at baseline, after RT and at three-year and six-year controls. In addition, cardiac magnetic resonance imaging (CMR) was performed at the six-year follow-up. The results were compared with cardiac RT doses. Results Global longitudinal strain (GLS) declined only modestly from baseline 17.9±4.1% to 17.6±2.7% at six-year control (p = 0.731) while apical regions showed significant decline from baseline 24.6±6.6% to 19.8±3.5% at six-year control (p<0.001). ProBNP increased from baseline 63.0 [37.0, 124.0] ng/l to 98.0 [50.0, 215.0] ng/l at six-year follow-up (p = 0.022). Patients with (n=14) and without (n=16) worsening of apical strain and increase in proBNP had maximal left ventricular radiation doses 46.9±4.8 Gy versus 40.1±12.9 Gy (p = 0.049), respectively. Lower values in CMR strain were concentrated in the apical regions with an association with regional RT doses. Each 1 Gy of regional radiation dose decreased local regional strain value in CMR by 0.356 % [95%CI; 0.244, 0.468] (p<0.001). Conclusions A significant increase in proBNP and a significant decrease in apical strain were observed after RT in six-year follow-up. A higher left ventricular maximal radiation dose was significantly associated with worsening in apical strain and proBNP. In addition, a worse regional strain values in CMR had a dose-dependent association with corresponding RT doses. These results indicate that even contemporary breast cancer RT induces progressive cardiac changes.