Markedly reduced insulin-like growth factor-1 in the acute phase of myocardial infarction

OBJECTIVES We investigated whether insulin-like growth factor-1 (IGF-1) is reduced in the early phase of acute myocardial infarction (AMI) and whether such a decrease might influence prognosis. BACKGROUND Insulin-like growth factor-1 protects against insulin resistance and apoptosis. Although insulin resistance has been reported in AMI, IGF-1 levels have not been investigated. METHODS We measured serum IGF-1 in 23 patients with AMI within 24 h of symp tom onset and in 11 matched controls. In the first 12 patients and controls , we also measured fasting insulin, diurnal growth hormone (GH) and insulin sensitivity (assessed as glucose disappearance or T/2 after an insulin bol us), and repeated IGF-1, insulin and GH after one year. In all patients, 90 -day cardiovascular death, recurrent ischemia, reinfarction, revascularizat ion and late malignant arrhythmias were assessed. RESULTS The AMI patients versus controls showed markedly reduced IGF-1 (115 +/- 112 vs. 615 +/- 300 ng/ml, p < 0.0001) and slower T/2 (-0.98 +/- 1.5 v s. -2.57 +/- 1.0 mg/dl/min, p = 0.01). Low IGF-1 often preceded the rise of myocardial necrosis markers. Patients with 90-day events (n = 12) versus t hose without had lower IGF-1 (47 +/- 54 vs. 189 +/- 110 ng/ml, p < 0.0001). Acute phase GH and insulin concentrations did not differ significantly fro m controls. After one year, the patients' IGF-1 values had risen to 460 +/- 242 ng/ml (p = 0.1 vs. controls, p < 0.0005 vs. acute phase), whereas GH l evels were lower (0.2 +/- 0.2 vs. 2.5 +/- 2.3 ng/ml, p = 0.01) and insulin levels higher (12.5 +/- 0.2 vs. 3.9 +/- 2.6 <mu>U/ml, p < 0.0001) compared with controls. CONCLUSIONS In the early phase of AMI, serum IGF-1 levels are markedly redu ced and may contribute to adverse outcomes. Reduced IGF-1 preceding the ris e of myocardial necrosis markers suggests a possible pathogenetic role. A c ompensatory increase in IGF-1 appears to occur by one year. CT Am Coil Card iol 2001;38:26-32) (C) 2001 by the American College of Cardiology.