Syndrome X clinical trials

Syndrome X and Endothelial Dysfunction

Cardiac syndrome X is characterized by angina, positve stress test, and patent coronary angiography, and its probable mechanism is microvascular dysfunction associated with endothelial dysfunction. We used brachial artery flow-mediated vasodilation to assess the endothelial function of the patients with syndrome X, coronary artery disease, and controls. Methods: We enrolled 28 patients with syndrome X, 11 healthy volunteers and 11 coronary artery disease patients. All subjects underwent a 2-step brachial artery flow-related vasodilation test: ultrasound artery diameter was measured at rest and after occlusion to assess endothelium-dependent vasodilation and after sublingual nitroglycerin to determine endothelium-independent condition. Serum endothelin-1 assay was performed for all participants. Results: The cardiac syndrome X patients had lower brachial artery dilation ratio (diameter after test/ diameter before test) than controls (1.10 +/- 0.09 versus 1.27 +/- 0.11, p=0.013), but the ratio is still higher than CAD patients (1.10 +/- 0.09 versus 1.02 +/- 0.07, p<0.001). After sublingual nitroglycerin, all 50 subjects had adequate vasodilation. Besides, normal controls have higher endothelin-1 level than the others. We concluded that syndrome X patients have worse endothelial function than healthy control, but patients of CAD had even worse endothelium function than cardiac syndrome X patients. Keywords: Cardiac syndrome X, coronary artery disease, endothelium-dependent vasodilation, endothelium-independent vasodilation, flow-mediated vasodilation, endothelin-1