Ischemia in Patients With Non-obstructive Disease (INOCA) in Italy INOCA IT Multicenter Registry"

Prospective, interventional, multicentre, non-randomized, single-arm open-label study that aims to enroll 200 consecutive patients with suspected chronic ischemic heart disease in the absence of obstructive coronary artery disease (INOCA) at clinically indicated coronary angiography in 3 Italian centers. During coronary angiography, these patients will be simultaneously subjected to a functional and coronary physiology study (according to the methods reported below): * Functional evaluation with fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), Resting Full-Cycle Ratio (RFR) of angiographic stenosis\> 50%; * In the presence of coronary angiographic stenosis \<50% or\> 50% but in the presence of a negative functional assessment (FFR\> 0.80 and iFR / RFR\> 0.90), coronary flow reserve (CFR) and index of microvascular resistance (IMR) will be measured. IMR and CFR will be assessed using intra-coronary guidance; * In the presence of CFR\> 2.0 and IMR \<25, tests with acetylcholine will also be performed in order to evaluate the possible presence of epicardial (focal or diffuse) or microvascular spasm.