Chemotherapy-associated cardiotoxicity in patients with breast cancer: assessment of myocardial work index by transthoracic echocardiography

Introduction Breast cancer is one of the most common malignancies worldwide. Despite advances in treatment, such as anthracycline-based chemotherapy and trastuzumab, which have contributed to increased survival of cancer patients, these therapies can increase the risk of cardiotoxicity, making cardiac monitoring crucial in this population. The Myocardial Work Index (MWI) has emerged as a tool to predict the risk of cardiotoxicity, especially in patients with significant blood pressure variations during treatment. Using the left ventricular pressure-strain loop technique, MWI evaluates myocardial work and calculates global work index (GWI), global wasted work (GWW), global constructive work (GCW), and global work efficiency (GWE). Purpose To determine the added value of myocardial work indices compared with global longitudinal strain (GLS) assessed by transthoracic echocardiography (TTE) in the diagnosis of chemotherapy-associated cardiotoxicity in women with breast cancer. Methods This was a retrospective, observational, descriptive-correlational study. A total of 40 women with breast cancer were included through a non-probabilistic sampling method, all of whom underwent chemotherapy with anthracyclines and adjuvant therapy with trastuzumab. Serial echocardiographic monitoring of systolic and diastolic function parameters was performed, including the assessment of global longitudinal deformation and myocardial work index, at four time points: pre-treatment (baseline TTE), first evaluation during treatment (TTE 2), second evaluation during treatment (TTE 3), and post-treatment (final TTE). Cardiac dysfunction related to oncological therapy was defined as a decrease in LVEF to < 50% and/or a relative reduction in GLS of > 15%, according to the 2022 consensus document of the European Society of Cardiology (ESC). Study variables: systolic and diastolic blood pressure, left ventricular ejection fraction (LVEF), GLS, global work index, global wasted work, global constructive work, and global work efficiency - analysed using EchoPAC™ software (version 206). Results The mean follow-up time between the first and last TTE was 17 months, with a standard deviation of 3.1 months. When analysed together and separately in two groups—women who developed cardiotoxicity and those who did not—the MWI indices showed patterns similar to GLS and LVEF, decreasing between TTE1 and TTE3 and partially recovering at final TTE, except for GWW, which behaved in the opposite manner. It was observed that in the group that developed cardiotoxicity, some women already had altered GWW and GWE before treatment. The most significant changes in all study variables occurred at TTE3. Conclusion This study highlighted the added value of MWI relative to GLS in diagnosing cardiotoxicity in women with breast cancer. The results showed that MWI behaves similarly to GLS, suggesting that combining the two methods—MWI and GLS—may enhance the detection of cardiotoxicity.Correlation between GLS and MWI