Background: Per the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Breast Cancer (available at NCCN.org), left ventricular ejection fraction (LVEF) should be evaluated prior to and during treatment with trastuzumab. Optimal frequency of assessment is unknown. The FDA label recommends monitoring prior to and every 3 months during therapy. Trastuzumab should be held for 4–8 weeks when LVEF decreases ≥16% from pretreatment values or LVEF is below normal limits and decreases ≥10% from pretreatment values. Trastuzumab should be permanently discontinued for persistent (>8 weeks) LVEF decline or if trastuzumab is stopped >3 times for cardiomyopathy (trastuzumab package insert). Methods: A retrospective chart review was performed analyzing 98 charts of patients with stage I–III HER2-positive breast cancer who were seen at the Edwards Comprehensive Cancer Center (ECCC) in Huntington, WV from January 1, 2012–December 30, 2017. Patients who received trastuzumab at ECCC (59) were further reviewed to see if cardiac function was assessed prior to treatment, at 3 month intervals, and if trastuzumab was held or discontinued permanently if indicated. Results: Analysis of 98 patient charts with stage I–III HER2-positive breast cancer was performed. 59 patients (60.2%) received trastuzumab under supervision of medical oncology at ECCC and continued in the study. LVEF was evaluated in all patients (100%) prior to treatment. LVEF was evaluated every 3 months in 36 (61%) patients while 23 (38.9%) occurred at longer time intervals. Preserved EF was seen in 41 (69.4%) patients. 18 (30.5%) patients had a decrease in LVEF by the defined criteria. Trastuzumab was not held appropriately in 4 of those patients (22.2%). 10 of 18 patients that had a drop in LVEF had persistent LVEF decline or had stopped treatment >3 times for cardiomyopathy. Trastuzumab was permanently discontinued appropriately in 4 of the 10 patients (40%). Conclusions: Better compliance is needed to monitor LVEF at 3-month intervals while on trastuzumab. Improvement to recognize when to hold trastuzumab to prevent cardiotoxicity is needed. Better documentation, easier accessibility to previous EF results, and a multidisciplinary team (breast navigator, cardiologist, oncologist, and pharmacist) will likely improve adherence to current recommendations for cardiac assessment and to determine if Trastuzumab should be held or stopped.