BACKGROUND: Antibodies against human epidermal growth factor receptor 2 (HER2) affect metastatic breast cancer cells and cardiac myocytes. Guidelines recommend evaluation of cardiac ejection fraction (EF) every 3 months despite little supporting evidence for this need. We assessed the impact of EF screening on clinical practice. PATIENTS AND METHODS: We carried out retrospective analysis of patients with HER2-positive metastatic breast cancer receiving HER2-directed therapy to assess the impact of aggressive cardiac screening on management decisions. RESULTS: Data for 128 patients were analyzed. The median number of EF screenings in the first year of therapy was 3 (range=1-8). A total of 29 patients had an asymptomatic decrease in EF. These patients had more EF screenings, more exposure to anthracyclines or left-sided radiation, were more likely to receive a cardiology consult and have an angiotensin converting enzyme inhibitor added to their therapy. Ninety patients underwent aggressive screening; this was not associated with cessation of HER2 therapy (p=0.92). CONCLUSION: Routine EF screening did not have an impact on decisions regarding HER2 therapy in patients with metastatic breast cancer. Given the known benefit of HER2 treatment, reducing the frequency of cardiac screening may be reasonable.