334 - Cardiac Management and Long-Termfollow-Up of Breast Cancer Patients Who Develop Mild Left Ventriculardysfunction While on Trastuzumab Therapy

Background: Trastuzumab significantly reduces the risk of breast cancer recurrence, but may be associated with an increased incidence of heart failure. Unlike anthracycline-related cardiotoxicity, trastuzumab related LVD is considered reversible. The intention of this study is to assess the cardiac management practices for patients with LVD in a non-trial setting and to evaluate the changes in management associated with the development of a local cardio-oncology clinic. Methods: Retrospective chart review was conducted for all patients who received adjuvant trastuzumab therapy in British Columbia for breast cancer between January 2010 and December 2013. The UBC Cardio-Oncology Clinic opened in 2011. Mild LVD was defined as a decline in left ventricular ejection fraction (LVEF) to 40–49% after starting trastuzumab. Charts were reviewed for demographic information, referral to cardiology, and long term cardiac follow-ups. Results: 962 patients received adjuvant trastuzumab during the study period. 106 (11%) patients had mild LVD and 8 (0.8%) patients had LVEF drop directly to <40%. Three emergency visits were required for symptomatic heart failure and there were no cardiac deaths. Of the 106 patients, 67 (63.2%) patients were referred to cardiology for management. The rate of referral increased over time (Fig. 1). After cardiology visit, 47/67 patients (70.2%) received beta-blocker, 58 (86.6%) received ACE inhibitors, 6 (9%) received loop diuretics, and 1 (1.5%) received mineralocorticoid receptor antagonist. The remaining 39 patients did not have a cardiology consultation and did not start new cardioprotective medications. On follow-up, 19/67 (28.4%) of patients had only a single cardiology consultation. The remaining 48 patients had an average of 4.3 ± 3.6 follow-up visits over 689 ± 514 days. On the latest cardiology visit, 47/48 (98%) were asymptomatic and euvolemic, and 44/48 (92%) of patients have recovered to a LVEF of >50% (other 4 patients remained in mild LVD). For the stable patients, 13/48 (27%) have started or have completed weaning off of medications. Conclusion: While LVD was found in 11.8% of patients after trastuzumab therapy, the majority of cases were mild and there were no cardiac deaths. Among patients receiving optimal medical management, nearly all recovered LV function, remaining asymptomatic and euvolemic. From 2010 to 2013, there was an increase in cardiology referrals and use of cardioprotective medications for the management of mild trastuzumab-related LVD, possibly related to the development of a local cardio-oncology clinic. Increased communication and collaboration between oncology and cardiology can further improve oncologic and cardiac outcomes for this population.