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.