Effects of HER2 Receptor Antagonist (Trastuzumab And Lapatinib) on Cardiac Chamber Size and Function Measured by Echocardiography Among Early HER2 Positive Breast Cancer Patients in a Tertiary Hospital

INTRODUCTION: The use of anti-HER2 breast cancer treatments, lapatinib and trastuzumab, improves patient outcomes but have been implicated to cause cardiac toxicity. This study aimed to evaluate the effect of these drugs on the cardiac size and function of patients, as measured by transthoracic echocardiography. METHODS: This is a retrospective study of patients who received lapatinib alone (group 1), concurrent lapatinib and trastuzumab (group 2), trastuzumab followed by lapatinib (group 3) and trastuzumab alone (group 4) and had serial 2D-echocardiographic monitoring at baseline, six months, one year and two years post-therapy from 2008 to 2016. The following measures were recorded and compared serially: E-point septal separation (EPSS), stroke volume (SV) measured by bi-plane method, cardiac output (CO), ejection fraction (EF), mid-right ventricular diameter (RV Mid), left atrial diameter (LA AP), left ventricular volume index (LAVI) and mid-right atrial diameter (RA A-L). Follow-up echocardiographic measurements were compared with baseline measures using one-way analysis of variance (ANOVA). RESULTS: Patients in group 1 had decreased mean EF by 1%, 1%, and 6%; decreased mean CO by 3%, 2% and 2%; increased mean mid V diameter by 7%, 3% and 21% and increased mean LA AP diameter by 15%, 8%, and 13% from baseline compared to six months, one year and two years post-therapy (p<0.001). Patients in group 2 had increased EPSS by 13% and 5% at six months and one year post-therapy vs baseline; decreased EF by 2%, 4% and 2%; and increased LA diameter by 9%, 17% and 19% respectively (p<0.001). Patients in group 3 had decreased EF by 2%, 5% and 3%; decreased mid LA diameter by 3%, 5% and 4% and decreased LAVI by 13%, 18% and 14% respectively (p<0.001). Group 4 had decreased SV by 2%, 27% and 10%; decreased EF by 5%, 3% and 3%; increased mid RA diameter by 7%, 6% and 4% and increased LA size by 0.5%, 15% and 5%, respectively (p<0.001). CONCLUSION: Lapatinib and trastuzumab, given alone, concurrently or sequentially, appear to affect cardiac size and function (EF, EPSS, RA and LA sizes) as measured by transthoracic echocardiography but not to levels beyond which the guidelines suggest treatment discontinuation.