10 Impact of altered cancer therapy-related cardiac dysfunction diagnostic criteria in an MRI breast cancer surveillance cohort

Introduction Herceptin (Trastuzumab) is a HER2 inhibitor targeted chemotherapy used to treat breast cancer. A significant side effect is cardiac toxicity in the form of cardiac injury, heart failure and cardiomyopathy known collectively as cancer therapy-related cardiac dysfunction (CTRCD). International guidelines recommend routine monitoring of cardiac function to identify asymptomatic development. Though primarily undertaken through echocardiography, due to resources and accessibility, Cardiac MRI (CMR) demonstrates greater accuracy and reproducibility. Recent 2022 European Society of Cardiology guidelines have amended diagnostic criteria. We sought to assess the impact of this change amongst a local cardiac MRI (CMR) only surveillance cohort. Materials and Methods Patients receiving Herceptin treatment for breast cancer in 2020 were identified and data collected for those who had undergone uninterrupted CMR only surveillance. Historically, CRTCD was defined as a drop in ejection fraction (EF) of 10% below 50% or by 15% overall, however as per 2022 European Society of Cardiology guidelines the definition was amended to a drop in EF by 10% below 50% only without biomarkers. Due to relative novelty, global longitudinal strain was not retroactively assessed. Results Of 183 patients receiving Herceptin treatment, 58 had continuous uninterrupted CMR surveillance during their disease course. Median follow up was 411 days with over 400 scans between them. Out of the 58 patients, whilst on Herceptin, nine developed CTRCD according to the old guidelines but only three were considered to have had CTRCD by updated guidelines. Discussion Though a small, retrospective cohort, a difference can be seen in CRTCD identification from the older to the newer ESC definition. Six of the nine patients who previously identified as having CRTCD requiring either critical treatment interruption and/or other additional therapies would, by updated definitions, no longer require this management alteration based on EF alone. This trend is reproduced in other studies. Conclusion While this study cannot comment on the effect this may have on clinical outcomes, there is a significant potential benefit in uninterrupted chemotherapy treatment for patients. In summary, the new ESC criteria seem to reduce the overall diagnosis of CRTCD compared to previous criteria in this small MRI-only surveillance cohort. Acknowledgements I would like to thank my colleagues and supervisor Dr Thomas for their assistance on this project. Secondly, I would like thank the BSCMR for this excellent opportunity to present our abstract.