Prognostic value of 6-minute walking test for early prediction of doxorubicin induced cardiotoxicity

Abstract

Abstract BACKGROUND/OBJECTIVES The 6-minute walking test (6MWT) is an easily performed, widely available and well-tolerated test for assessing the functional capacity of patients with HF in everyday clinical practice. The measurement properties of the 6MWT, such as reliability and validity, have been studied in patients with chronic heart failure, coronary artery disease, and cancer. However, little is currently known about the 6MWT and cardiotoxicity. The study was aimed at assessing the incidence of cancer therapy-related cardiovascular toxicity, identified the role of 6MWT as early predictor of early onset cardiotoxicity. Methods We performed a prospective study of 85 patients with breast cancer, treated with doxorubicin-based chemotherapy in the Department of Oncology and Hematology. 2D echocardiography and speckle tracking echocardiography were performed before anticancer treatment was started and after the treatment. We defined anthracycline-induced subclinical cardiotoxicity if a decline in global longitudinal strain (GLS) by >15% from baseline was observed and based on that patients were divided into two groups– patients with subclinical cardiotoxicity and patients without subclinical cardiotoxicity. The 6MWT was developed by the American Thoracic Society comprehensive guidelines. The 6MWT was performed in a long straight hospital corridor, over a 30-m distance. Statistical analysis was performed with „IBM SPSS statistics 27.0" program. Statistical significance level p<0.05. Results In the study population statistically significant GLS reduction was detected before and after the anticancer treatment (-21±0.53 vs. -18.1± 1.18, p<0.01). Of 85 women (mean age, 54.5 (9.3) years) subclinical left ventricle dysfunction was identified in 51 (60%). We found a significant negative correlation between baseline 6MWT and cardiotoxicity (r = 0.3 and p = 0.02). The baseline 6MWT results were significantly lower among patients with subclinical cardiotoxicity (494.3 ± 40.5 m vs 629.8 ± 60.1 m, p<0.001). The diagnostic validity of 6 MWT as a cardiotoxicity biomarker was evaluated using the non-parametric ROC curve (Pic. 1). We obtained an optimal cut-off point of 6MWT of ≤540m. (AUC = 0.98; p < 0.001). Conclusions Baseline 6MWT may be used as independed prognostic predictor of subclinical anthracycline-induced cardiotoxicity.ROC curve for 6MWT and cardiotoxicity