 Background Myocardial ischemia is caused by myocardial oxygen supply and demand mismatch. Despite that coronary artery disease CAD is the major cause of myocardial ischemia, the symptoms may occur even in the absence of significant CAD. One of the mechanisms suggested for myocardial ischemia in these patients is microvascular ischemia i.e. mismatch in microscopic vessels, affecting the myocardium i.e. heart muscle at the cellular level. 