Myocardial ischemia with nonobstructive coronary arteries (INOCA). Part I. The current state of INOCA problem

INOCA (ischemia with nonobstructive coronary arteries) is a general term for different types of coronary artery disease which excludes an obstruction of the coronary arteries: vasospastic angina, microvascular angina and muscular myocardial bridge. According to coronary angiography data, 37–39% of patients don’t have hemodynamically significant stenoses of the coronary arteries. INOCA is assigned with significant quality of life limitations, decreased working capacity, the risk of major cardiovascular events is higher and survival rate is lower than in a healthy population. Two main pathogenetic mechanisms were studied and differentiated based on scientific data: microcirculatory dysfunction and vasospasm. Myocardial bridge is classified as structural vasospasm endotype. Coronary blood flow examination and an acetylcholine provocation test are the main diagnostical procedures, which can help to determine the leading pathophysiological mechanism of INOCA. Microvascular disease treatment is pretty similar to an obstructive coronary disease therapy with the possible addition of metabolic therapy. In vasospastic angina front-line drugs are calcium antagonists.