Insulin Resistance as an Independent Risk Factor for Carotid Artery Wall Intima Media Thickening in Vasospastic Angina

Studies have shown the presence of insulin resistance together with compensatory hyperinsulinemia in vasospastic angina as well as obstructive coronary artery disease. There is growing evidence that the development of coronary atherosclerosis may be closely related to systemic atherosclerosis as well as coronary spasm. However, no information is available about the possible relationship between insulin resistance and the existence of carotid atherosclerosis in vasospastic angina without segmental stenosis or luminal irregularities in coronary angiograms. To evaluate the independent effect of insulin resistance on carotid intima media thickening, we performed insulin sensitivity tests (steady-state plasma glucose method) on 40 patients with vasospastic angina and 24 control subjects with angiographically intact coronary arteries. Both oral glucose tolerance tests and lipid analyses were performed. Using B-mode ultrasonography, we assessed intima media thickness and plaque formation of common carotid arteries in these subjects. The steady-state plasma glucose level in the vasospastic angina group was about twofold higher than that of the control group, confirming the presence of insulin resistance in patients with vasospastic angina. The patients with vasospastic angina showed a significant increase in the average intima media thickness of the carotid wall and frequency of plaque formation, although they were comparable to the control subjects in risk factors other than insulin resistance. The intima media thickness was correlated with age (r = .62, P < .001), 2-hour insulin area (r = .45, P < .01), and steady-state plasma glucose level (r = .68, P < .0001) in patients with vasospastic angina. Similar correlations were observed in the control subjects. Multiple regression analyses of data indicated that 67% of the variation in the intima media thickness could be accounted for by age, steady-state plasma glucose level, and cigarette-years in vasospastic angina. In addition, differences in IMT were independently related to vasospastic angina. These results suggest that insulin resistance in association with compensatory hyperinsulinemia may be an important pathogenic factor for the development of coronary artery spasms and systemic early atherosclerosis. (Arterioscler Thromb Vasc Biol. 1997;17:3302-3310.)