FNDC5 and heart failure: Cardiac cachexia in heart failure with reduced ejection fraction is associated withimpaired energy homeostasis due to anabolic and catabolic imbalance, and serumadropin and irisin levels play important roles in energy balance and metabolism.Based on the aforementioned, we hypothesized that both serum adropin and irisinlevels would differ in cachectic heart failure with reduced ejection fractionpatients and non-cachectic individuals.