 - Reactive hyperemia index RHI test of endothelial function: peripheral endothelial function will be assessed using EndoPAT2000 technology Itamar-Medical Ltd., Caesarea, Israel. EndoPAT technology measures changes in peripheral artery tone PAT signal in response to a five-minute occlusion of the brachial artery with a pressure cuff. This arterial occlusion elicits a post-ischaemic NO-dependent endothelial vasodilatation which causes an increase of the PAT signal. EndoPat technology is a noninvasive measurement, and requires only a finger probe and a blood pressure cuff. It is Food and Drug Administration FDA approved. Only those patients with abnormally reduced endothelial function LnRHI0.7 will be enrolled. 