Incidence and risk factors of trastuzumab-induced cardiac dysfunction in a predominantly Hispanic South Texas population: a descriptive study

BACKGROUND: Trastuzumab, a monoclonal antibody against human epidermal growth factor receptor 2 (HER2), is often the first line treatment for HER2 positive breast cancer. Although trastuzumab is effective, it has cardiotoxic effects and therefore requires cardiotoxicity monitoring via serial transthoracic echocardiograms (TTEs). We aimed to evaluate risk factors for trastuzumab related cardiac dysfunction in a South Texas population that is uniquely a majority Hispanic population. METHODS: A retrospective study was conducted of female patients with HER2-positive breast cancer who received trastuzumab treatment from 2015 to 2021. A total of 180 patients were identified. Patients without a baseline TTE and a baseline left ventricle ejection fraction (LVEF) less than 53% were excluded. The final sample size included 132 patients. Cardiac dysfunction was defined as a drop in LVEF by more than 10% to less than 53% during the 1-year study period. RESULTS: The incidence of cardiac dysfunction was 6% in the study population. Hispanic/Latino patients composed 58% of the study population and represented 50% of patients who experienced cardiotoxicity. Of the patients who developed cardiotoxicity, 50% had hypertension, 25% had hyperlipidemia, 12.5% had type 2 diabetes mellitus, and 12.5% had previous coronary artery bypass grafts. A total of 12.5% had a history of radiation, 25% had a history of anthracycline therapy, 37.5% were former smokers, and 25% were former alcohol users. CONCLUSIONS: The incidence of trastuzumab-related cardiotoxicity in this Hispanic/Latino majority-minority population was 6%, which is surprisingly lower than the 9% cardiotoxicity rate observed in a predominantly white population in a previous study by Otchere et al., in 2023. Further studies are needed to determine the factors contributing to the reduced cardiotoxicity rate observed in this Hispanic population.