Endotrophin, a type VI collagen cleavage product, has fibrosis, and insulin resistance effects. Type VI collagen also plays a role in cardiac fibrosis. In this study, we aimed to investigate the role of endotrophin in the pathogenesis of cardiac fibrosis by determining its levels in patients with heart failure with reduced and mid-range ejection fraction (EF). We also aimed to determine the possible association between endotrophin and treatment that prevents ventricular fibrosis.