Early, intracoronary growth hormone administration attenuates ventricular remodeling in a porcine model of myocardial infarction

ObjectiveVentricular remodeling is a common corollary of myocardial infarction. We hypothesized that this process may be attenuated by growth hormone, administered as a single high-dose, selectively in the infarct zone, early postmyocardial infarction.DesignIn 35 pigs (29 ± 4 kg), myocardial infarction was generated by inflation of an over-the-wire angioplasty balloon in the circumflex artery for 60 min and 5 further pigs were sham-operated. Ten minutes after reperfusion, the pigs were randomized (2:1) to either growth hormone (1 IU/kg) (n = 23) or normal saline (n = 12), delivered via the balloon catheter. All survivors were treated with captopril and were sacrificed 4 weeks after myocardial infarction.ResultsCompared to controls, growth hormone-treated animals displayed lower heart weight (4.1 ± 0.5 g/kg body weight, versus 3.4 ± 0.4 g/kg, respectively, p = 0.003) and dimensions (left ventricular short axis diameter 46 ± 7 mm versus 37 ± 6 mm, p = 0.01; right ventricular short axis diameter 38 ± 7 mm versus 30 ± 5 mm p = 0.001). Growth hormone increased wall thickness in the infarct (6.0 ± 1.8 in controls versus 9.9 ± 3.7 in treated animals, p = 0.004) and non-infarct zones (10.6 ± 1.8 in controls versus 15.5 ± 3.8 in treated animals, p = 0.0006) and produced higher (p < 0.05) microvascular density in both zones.ConclusionIntracoronary administration of growth hormone attenuates left and right ventricular remodeling by inducing hypertrophy and by enhancing angiogenesis.