To evaluate the circulating levels of remodeling biomarkers procollagen type 1 C-terminal propeptide (PICP), human cartilage glycoprotein-39 (YKL-40), plasma renin activity (PRA), aldosterone (Aldo) as well as clinical and echocardiographic parameters in patients with heart failure with reduced ejection fraction (HFrEF), before and after treatment with Sacubitril/Valsartan (S/V). The gene discussed is REN; the disease is heart failure.