Stress echo in microvascular disease

Coronary microcirculation is a fundamental portion of the coronary artery tree, as it contains most of the coronary blood volume and represents the main regulator of the coronary blood flow. Arterioles, capillaries, and venules originating from the major coronary artery branches and extending inside myocardium, with a diameter less than 300 μm, constitute the whole coronary microcirculation. While in the past only epicardial segments of coronary arteries were recognized to be potentially diseased by atherosclerotic process, in the last years growing evidences have suggested that some impairment may also affect the microcirculation. Interestingly, coronary microvascular impairment greatly contributes to pathophysiology of many cardiac diseases and to patient prognosis. As worth of note, different degrees of coronary microvascular impairment can be found both with and without epicardial obstructive atherosclerosis: indeed, recently, coronary microvascular abnormalities have been described in patients with normal coronary angiograms. Several conditions can be clustered together in the syndrome of microvascular disease (Table 30.1) [1]. In some of these conditions, the abnormalities of the microvasculature represent important markers of risk and may even determine myocardial ischemia, thus becoming important therapeutic targets [1].