Breast-conserving surgery is a widely used treatment for breast cancer, often followed by adjuvant therapy such as adjuvant paclitaxel and trastuzumab (APT). While APT effectively reduces local recurrence and distant metastasis, it may also impair left ventricular systolic function. Speckle tracking imaging (STI) is a noninvasive ultrasound technique that quantitatively evaluates overall cardiac function. It allows for the assessment of myocardial fibrosis, myocardial injury, and overall systolic function, making it a valuable tool in clinical practice. This review discusses recent advances in the use of STI for evaluating left ventricular systolic function following APT in breast cancer patients.