Insulin-like growth factor-I, insulin, and angina pectoris secondary to coronary atherosclerosis, vasospasm, and syndrome X

It was recently reported that serum concentrations of insulin-like growth factor-I (serum total IGF-I) are reduced in patients with significant coronary atherosclerotic stenoses.' The rationale for the investigation was the notion that when growth hormone (GH)-deficient subjects are abnormally prone to develop early coronary atherosclerotic disease(2) and GH-deficient patients have low serum IGF-I, then patients with coronary atherosclerosis may be GH-deficient and have low serum IGF-I. This may seem a somewhat unfounded syllogism, but patients with coronary artery disease actually demonstrated reduced serum concentrations of IGF-I even though serum IGF-I did not correlate with the extent of coronary artery disease (coronary score). To confirm and enlarge this hypothesis, we measured a number of GH- and IGF-related substances in controls--not only in patients with classic coronary artery disease (CAD), but also in patients with angina pectoris and normal coronary angiograms in the presence of a positive exercise test (''syndrome X'') and in patients with angina pectoris and demonstrable epicardial spasm in the absence of significant stenoses (''variant angina'').