Does Endothelial Dysfunction Cause Myocardial Ischemia?
The results of this study are provocative and consistent with the notion that appropriate release of relaxing factors from the coronary endothelium on stimulation by shear stress and unknown circulating agonists importantly regulates coronary flow responses to stress. Accordingly, limited or absent release of relaxing factors on provocation could be anticipated to expose the coronary vasculature to the unopposed effect of agonists that constrict vascular smooth muscle, as evidenced by acetylcholine-induced constriction of epicardial coronary segments and diminution in coronary flow from baseline values in the group with LAD territory perfusion defects. The results of this study could provide incentive for widespread testing of this sort in patients with chest pain despite normal coronary angiograms or insignificant coronary disease in an attempt to identify those patients who have a coronary-based ischemic syndrome. However, the critical question of pathophysiological relevance that mu
