A Prospective Cohort Study on Cardiotoxicity of Adjuvant Trastuzumab Therapy in Breast Cancer Patients

Background: Cardiotoxicity is an important side effect of trastuzumab therapy and cardiac surveillance is recommended. Objectives: The aim of our study was to prospectively assess baseline patients' characteristics, level of N-terminal pro-brain natriuretic peptide (NT-proBNP) and echocardiographic parameters as possible predictors of trastuzumab-related cardiac dysfunction. Methods: In a prospective cohort study, clinical, echocardiographic and neurohumoral assessment was performed at baseline, after 4, 8 and 12 months in breast cancer patients undergoing post-anthracycline (3-4 cycles) adjuvant therapy with trastuzumab. Trastuzumab-related cardiac dysfunction was defined as a decline of >= 10% in left ventricular ejection fraction (LVEF). Results: 92 patients (mean age, 53.6 +/- 9.0 years) were included. Patients who developed trastuzumab-related LVEF decline >= 10% (20.6%) during treatment had significantly higher baseline LVEF (70.7 +/- 4.4%) than those without (64.8 +/- 5.5%) (p = 0.0035). All other measured baseline parameters (age, body mass index, arterial hypertension, level of NT-proBNP and other echocardiographic parameters) were not identified as significant. Conclusions: Our findings suggest that baseline patient' characteristics, level of NT-proBNP and echocardiographic parameters, as long as they are within normal range, are not a reliable tool to predict early trastuzumab-related cardiac dysfunction in patients undergoing post-low dose anthracycline adjuvant trastuzumab therapy. A LVEF decline in patients with high-normal baseline level although statistically significant is not clinically relevant. (Arq Bras Cardiol. 2016; 107(1):40-47)