IGF1 and Abnormal renal physiology: COX regression analysis (Table 2) showed that the factors independently associated with the cardiovascular mortality in patients with HFrEF were as follows: (i) severe renal dysfunction (eGFR ≤ 30 ml/min/1.73 m2), (HR stage III = 1.63, 95% CI 0.73–3.63, p = 0.16; HR stages IV–V = 4.86, 95% CI 1.48–15.95, p = 0.009), respectively; (ii) being classified as high-risk patient of mortality/unexpected death (HR 2.25, 95% CI 1.04–4.86, p = 0.039), and (iii) serum IGF-1 (HR 0.42, 95% CI 0.23–0.77, p = 0.005).