Background: Circulating mononuclear cells could be activated with endothelial inflammation in patients with coronary artery disease (CAD). In some patients with normal coronary angiograms, myocardial ischemia could also present with coronary microvascular dysfunction (cardiac syndrome X). This study was undertaken to investigate whether mononuclear cell activation and endothelial inflammation can present in syndrome X patients.
Methods: We evaluated the biochemical parameters, circulating soluble adhesion molecules, circulating superoxide free radicals, and mononuclear cell activity in 32 patients with syndrome X, 34 with angiographically documented CAD, and 17 age- and gender-matched healthy control subjects.
Results: Compared to that in control subjects, plasma high-density lipoprotein was reduced (P<0.001) and insulin to glucose ratio increased (P=0.02) in CAD patients. Circulating level of soluble intracellular adhesion molecule-1 was significantly higher in both syndrome X and CAD patients than in control subjects (P<0.01), whereas the levels of soluble vascular cell adhesion molecule (P=0.02) and von Willebrand factor (P=0.01) were increased in CAD patients only. The peak (P<0.001) and total counts of superoxide free radicals in whole blood (P<0.001) was significantly higher in syndrome X patients than in the other two groups. However, phorbol-12-myristate-13-acetate-induced superoxide free radical generation of mononuclear cells was increased in CAD (10.5+/-4.6%, P=0.01) but not in syndrome X patients (8.7+/-2.0%) as compared with control subjects (7.7+/-0.5%).
Conclusions: The results indicated that the activity of mononuclear cells was increased with significant endothelial inflammation and injury in CAD patients. In syndrome X patients, though circulating superoxide free radicals were increased, there was minimal endothelial inflammation without mononuclear cell activation. The relatively preserved lipid and metabolic profiles might contribute to less vascular inflammation in syndrome X patients.