Background: Elevations in coronary artery calcification (CAC) scores detected by electron beam computed tomography (EBCT) correlate with the extent of atherosclerosis and are predictive of subsequent coronary events. Arterial endothelial function can be assessed by measuring the brachial artery vasodilatory response to hyperemia. We evaluated the correlation between endothelial dysfunction and the degree of coronary calcification in asymptomatic patients with a spectrum of risks for atherosclerosis. Methods: We studied 65 asymptomatic patients presenting for EBCT of the coronary arteries. High-resolution ultrasound was used to measure brachial artery diameter before and after wrist occlusion to induce reactive hyperemia. Studies were analyzed by 2 investigators blinded to the CAC score; results are expressed as % diameter change from baseline. Results: Brachial artery vasoreactivity correlated negatively with CAC score (r=-0.39, p<0.01). Patients were prospectively divided by presence or absence of significant coronary calcification into groups with low (<100; n=49) and high (>100; n=16) CAC scores. As expected, there was a significant difference in CAC scores between groups (12 vs 414, p<0.01). There was no difference between groups in the following known cardiac risk factors: age (50.7 vs 50.5, p=NS), percent male (64 vs 87%, p=NS), blood pressure (systolic 125 vs 126, diastolic 74 vs 77 mm Hg, p=NS), or total cholesterol (210 vs 205 mg/dl, p=NS). Diabetes was present in only 4 of 65 patients; all had low CAC scores. Brachial artery vasoreactivity was significantly decreased in the patients with high CAC scores (% increase, 3.71 ± 0.48% vs 7.64±0.47%, p<0.01). Conclusions: In this population of asymptomatic patients, elevations in CAC scores correlated with impaired endothelial function. High CAC scores have previously been shown to predict subsequent cardiac events in asymptomatic subjects. Endothelial dysfunction accompanies even mild atherosclerosis and may play a role both in its mechanism of development and in the propensity for future cardiac events.
ASJC Scopus subject areas
- Critical Care and Intensive Care Medicine