BACKGROUND: Cancer breast is the most common malignancy worldwide in females and is commonly treated using regimens based on anthracycline therapy. Cardiac complications related to breast cancer treatment using chemotherapy can manifest as either acute, subacute, or chronic dysfunction of the heart. Most of the signs of cardiotoxicity are subclinical. Our study aimed to evaluate left atrial strain (LAS) changes before and after anthracycline-based therapy in patients with breast cancer. One hundred and twenty patients with invasive breast cancer stages I-III eligible to receive anthracycline-based chemotherapy were enrolled in the study. We used doxorubicin 60 mg/m RESULTS: We initially enrolled 120 patients in this observational cohort prospective study. Twenty-six patients were excluded. All LAS measures were significantly reduced at follow-up with a significant positive correlation with left ventricular global longitudinal strain. 56.4% of our patients were hypertensive, and 81% of hypertensive patients received angiotensin-converting enzyme inhibitors (ACEI). The subgroup of patients who received ACEI for treatment of HTN had a lower rate of left atrial strain changes following anthracycline therapy compared with non-ACEI-treated patients, either hypertensive or not. CONCLUSION: We concluded that LAS deteriorated usually after anthracycline treatment, and it predicted early chemotherapy-induced cardiotoxicity.