Use of myocardial strain imaging by echocardiography for the early detection of radiotherapy-induced cardiotoxicity in breast cancer patients (BACCARAT Study)

Abstract

Background Radiotherapy (RT) is a major component of breast cancer treatment. However, breast RT is associated with long-term cardiac toxicity with clinical detection only relevant 10 to 15 years after RT. Early surrogate end-points, predictive for the development of later cardiac events, would be useful. Purpose To evaluate echocardiographic strain imaging for the detection of sub clinical myocardial dysfunction arising after breast cancer RT. Methods BACCARAT is a monocentric prospective cohort study of unilateral breast cancer patients treated with RT but without chemotherapy. They are followed for 2 years with repeated cardiac imaging examinations, including 2-dimensional speckle strain imaging for the detection of sub clinical left ventricular abnormalities. Results Between October 2015 and December 2017, this study prospectively included 114 women (95 left-sided and 19 right-sided) aged 58\xa0±\xa08 years. Cardiac evaluations with strain imaging are performed before RT, 6 months and 24 months after RT. At this stage of the study, strain imaging measurements before RT and RT\xa0+\xa06 months are available for 65 patients. Mean heart and left ventricle doses were 2.9\xa0±\xa01.3\xa0Gy and 6.1\xa0±\xa02.9\xa0Gy for the left-sided patients, 0.4\xa0±\xa00.1\xa0Gy and 0.1\xa0±\xa00.04\xa0Gy, respectively, for the right-sided patients. A decrease in global longitudinal strain was observed at 6 months post-RT for left-sided patients (−14.1%\xa0±\xa03.6% at 6 months after RT vs. −15.4%\xa0±\xa03.2% before RT, percentage of change 9.2%, P\xa0=\xa00.02) but not for right-sided patients. No significant change was observed with conventional echocardiography left ventricular ejection fraction measurement. Conclusion These preliminary results demonstrate a statistically significant reduction of global longitudinal strain 6 months after RT. Further investigation of BACCARAT study could illustrate strain imaging may have a potential role for screening and identification of patients at risk to develop cardiac complications.