Usefulness of Left Atrial Remodeling in Predicting CardiacToxicity During Trastuzumab Therapy for Breast Cancer

Trastuzumab is a key therapy for patients with human epidermal growth factor receptor 2 positive breast cancer (BC). However, it may cause left ventricular dysfunction, resulting in withdrawal of therapy. Left atrium (LA) enlargement has proven to cue subclinical ventricular dysfunction in various clinical setting. Aim of the study was to investigate the association between LA volume index (LAVI) change over time and the development of Cancer Therapeutics Related Cardiac Dysfunction (CTRCD). Consecutive human epidermal growth factor receptor 2 positive BC patients were retrospectively included. Transthoracic echocardiography was performed before starting Trastuzumab and at every 3 up to 12 months. LA volume was measured using the modified Simpson's rule and indexed for body surface area. Ninety patients formed the study population. All patients had a complete 12 months follow-up. Mean baseline LAVI was 27 ± 8 ml/m 2 and it was dilated (≥34 ml/m 2 ) in 10 patients (11%). During follow-up, CTRCD occurred in 19 (21%) patients and there was modest LAVI enlargement, with a mean increase of 3 ± 2 ml/m 2 (p = 0.0002 vs. baseline). LAVI dilation was significantly higher in patients with CTRCD (average increase at the time of CTRCD vs. baseline: 7 ± 6 ml/m 2 , p = 0.008), versus patients without CTRCD (average increase at 12 months of follow-up 2±1, p = 0.02), p for comparison = 0.004. LAVI dilatation over time predicted CTRCD independently from baseline LAVI values and the presence of systemic arterial hypertension (OR for 5 ml/m 2 dilation was 1.56 [95%CI 1.09 to 2.37], p = 0.01). Trastuzumab related CTRCD is associated with significant LAVI morphological remodeling in BC patients.