The potential effects of IGF-1 and GH on patients with chronic heart failure

Heart failure (HF) is an important health concern with almost a quarter million deaths each year despite advances in medical therapy. Improvement of cardiac function has been shown to reduce morbidity and mortality in patients with HF. There has been recent interest in the growth hormone (GH) / insulin-like growth factor (IGF) pathway as a potential therapeutic target for patients with HF. Insulin-like growth factor 1 has been shown to augment cardiac function ex vivo and in animals. It was hypothesized that IGF-1/IGF-binding protein 3 levels might be able to provide prognostic benefits in patients with heart disease. Initial observational studies have shown significant benefits from GH supplementation including improved ejection fraction, increased exercise tolerance, and decreased New York Heart Association functional class. These results, however, were not replicated in randomized, controlled trials. Patients with advanced stages of HF might develop cachexia associated with a state of significant GH resistance. The lack of response to GH supplementation may be secondary to a deficiency in IGF-1, the effector hormone. Hypothetically, this group of patients could benefit from direct IGF-1 supplementation. Combined therapy with GH and IGF-1 is appealing; however, future trials in patients with advanced HF are warranted to prove this concept.