Endothelial dysfunction as assessed by flow-mediated dilation in patients with cardiac syndrome X: role of inflammation

Background: Endothelial dysfunction, reduced coronary flow reserve and increased markers of inflammation are detectable in cardiac syndrome X (CSX). In this study we investigated the relation between inflammation and systemic endothelial function in CSX patients. Methods: We studied 42 CSX patients (55±6 years, 14 men) and 20 healthy subjects (52±7 years, 9 men). Systemic endothelial function was assessed by flow-mediated dilation (FMD) of the brachial artery after 5-minute of forearm cuff inflation. Serum C-reactive protein (CRP) was measured by a high-sensitivity method. Results: FMD was significantly lower in CSX patients compared to controls (4.8±4.4 vs. 13.7±4%, p<0.001), whereas CRP levels were higher in CSX patients than in controls (2.7±2.4 vs. 0.7±0.4 mg/L, p=0.001). In CSX patients FMD showed a significant inverse correlation with CRP levels, even after adjustment for potentially confounding variables (r=-0.34, p=0.006). Conclusion: An impaired FMD is detectable in CSX patients, suggesting a generalized abnormality in vascular function. Subclinical inflammation seems to play a significant role in the impairment of endothelium-dependent vasodilator function of these patients.