Background: Chemotherapeutic agents have many side effects; among them is cardiotoxicity. Ejection fraction fails to detect the subtle alterations of left ventricular (LV) function; that is why there is a need for a more sensitive tool. The aim is to detect subclinical LV systolic dysfunction after chemotherapeutic treatment, using NT-BNP plasma level as well as speckle tracking echo-global longitudinal strain (STE-GLS). Seventy-four asymptomatic, non-metastasizing breast cancer female patients without risk factors were included. They were assessed before and 6 weeks after taking their first chemotherapeutic session. Assessment included clinical characteristics, conventional two-dimensional (2D) and three-dimensional (3D) echocardiography, and 2D STE-GLS. Blood samples for NT-BNP plasma level were collected on both visits and were later analyzed using a Sandwich ELISA technique.
Results: The median NT-proBNP almost doubled after 6 weeks of chemotherapy (73.50 vs 34.4 pg/L, p value <0.001). Only two patients showed significant reduction of LVEF >10% to less <55%. One patient died before her scheduled follow-up visit, and the cause of death is unknown. Fifty patients showed elevated follow-up levels of the NT-BNP. As compared to the baseline visit, 12 patients had a high relative reduction of the LV-GLS (>15%) and all of them had a relatively higher NT-proBNP. A 2.2 relative elevation of the NT-proBNP was able to define a relative reduction of LV-GLS >15% by a 100% sensitivity and 81.8% specificity.
Conclusion: The relative reduction of LV-GLS and the relative elevation of NT-proBNP were successful in defining subclinical, subtle chemotherapy-induced cardiotoxicity after 6 weeks of the first chemotherapeutic agent administration.
Keywords: Brain Natriuretic peptide; Cardiotoxicity; Chemotherapy; Echocardiography.