GH-independent cardiotropic activities of hexarelin in patients with severe left ventricular dysfunction due to dilated and ischemic cardiomyopathy

Aim: To investigate acute cardiotropic activities of hexarelin in patients with severe left ventricular dysfunction due to ischemic (iCMP) and dilated cardiomyopathy (dCMP). Methods and results: We studied the effect of intravenous hexarelin administration on growth hormone (GH) levels and left ventricular ejection fraction (LVEF) evaluated by radionuclide angiography in eight patients with dCMP (age 53.0 +/- 2.8, LVEF 16.7 +/- 2.1%) and five patients with iCMP (age 52.0 +/- 2.8 years, LVEF 22.6 +/- 2.1). Results were compared with a group of seven normal subjects (age 37.4 +/- 3.4 years, LVEF 64.0 +/- 1.5%) and seven patients with severe growth-hormone deficiency (GHD; age 42.0 +/- 4.4 years, LVEF 50.0 +/- 1.9%) previously studied with the same methodology. In dCMP and iCMP patients hexarelin induced a similar significant (P < 0.05) increase in GH levels. In iCMP patients hexarelin induced a LVEF increase (peak LVEF 26.2 +/- 2.5%, P < 0.05) as observed in normals and GHD, while in dCMP LVEF was unchanged (peak LVEF 17.7 +/- 1.7, P = NS). In all groups other hemodynamic parameters were unchanged. Conclusions: Acute hexarelin administration increases LVEF in iCMP patients (as in normals and GHD) but not in dCMP patients in spite of a similar GH releasing effect and basal LVEF. A possible explanation of the positive inotropic effect of hexarelin in iCMP could be a direct stimulation on viable myocardium or myocardial contractile reserve. (C) 2002 European Society of Cardiology. Published by Elsevier Science B.V. All rights reserved.