Insulin-like growth factor-1 in early-onset coronary artery disease: Insights into the pathophysiology of atherosclerosis.

percutaneous coronary intervention. Patients with acute coronary syndromes or coronary interventions in the previous 6 months were not considered eligible for the study. Controls were nondiabetic adults ≤45 years without cardiac symptoms or known CAD. Blood was collected after a 12-hour fast for glucose, total cholesterol, LDL and HDLcholesterol, triglycerides, IGF-1 and insulin measurements. IGF-1 was measured by chemiluminescent enzyme-labeled immunometric assays (Immulite 2000, Diagnostic Products Corporation, USA), and serum insulin was measured by radioimmunoassay (ImmuChemTM Coated Tube, MP Biomedicals, USA). CIMT measurement was performed with a 7.5-MHz ultrasound system (GE Healthcare, Wisconsin, USA) by 2 trained sonographers. Scans of the right and left last distal centimeter of common carotid arteries and bifurcation and of the first proximal centimeter of internal carotid arteries in 3 different projections (anterior, lateral, and posterior) were performed. Measurements were made on longitudinal scans by using the machine's electronic caliper. Values for the 3 different projections and for right and left carotid arteries were averaged to obtain the mean maximum CIMT. For the analysis of agreement between observers, a Bland–Altman analysis was employed. There was good concordance between observers (0.73–0.91). The study complied with the Declaration of Helsinki. All participants gave informed written consent and study approval was obtained from the local ethics committee. Categorical variables were expressed as number and percentage and compared with a chi-square test. Continuous variables were expressed as mean ± SD or median and interquartile range and compared with the Student's t test or Mann-Whitney's test according to their distribution (normal or skewed). Correlations between CIMT and candidate variables of interest were studied with the Pearson's test. Linear regression analysis was employed to evaluate variables independently associated with CIMT in the entire population; traditional risk factors were entered into the model, and IGF-1 and insulin were then separately entered to assess their contribution over and above the other risk factors. A value of p b 0.05 was considered statistically significant. Nineteen patients (84.2% with prior myocardial infarction, 26.3% with prior coronary artery bypass surgery and 68.4% with prior percutaneous coronary intervention) and 17 controls were studied. Table 1 depicts their characteristics. There was a small, statistically significant difference in age, which was not considered biologically important since patients remained at the “young for coronary artery disease” age range and very close to controls. Early-onset CAD patients had higher body mass index, fasting glucose and triglycerides and lower HDL-cholesterol. Of note, total cholesterol and LDL-cholesterol were not significantly