Insulin-like growth factor-binding proteins 2 and 3 are independent predictors of a poor prognosis in patients with dilated cardiomyopathy

Growth hormone and its mediator insulin-like growth factor 1 (IGF1) exert various actions on the growth and proliferation of myocardium and many other cell types. IGF1 is predominantly bound to at least six binding proteins (IGFBP1–6). Growth hormone is the major hormonal factor controlling IGF1 and IGFBP concentrations. Tissue concentrations, bioavailability and effects of IGF1 are regulated by modifications of IGFBP affinities through proteolysis, phosphorylation and binding to cell surfaces.1 In a failing myocardium, growth hormone and IGF1 improve cardiac haemodynamics, normalise the calcium homoeostasis and support an efficient myocardial energy metabolism.2 However, analyses of the IGF1 serum levels in patients with congestive heart failure (CHF) from different causes showed increased as well as unchanged levels. Furthermore, despite improvements of cardiac function in several small open growth hormone-substitution studies, these effects could not be confirmed in two large randomised double-blind studies.2 Nevertheless, we observed a marked increase of the left ventricular ejection fraction in patients with a pronounced increase of IGF1 serum levels during recombinant human growth hormone treatment.3 Thus, we assume that the growth hormone/IGF-system is differently altered in patients with CHF due to different causes and might influence the course of the disease. We examined 90 patients with idiopathic dilated cardiomyopathy between 1992 and 1997 after exclusion of secondary forms and …