The Euro-CRAFT Registry

Inclusion Criteria: * Age \> 18 years. * Stable patients should have complaints of chest pain suspected of angina pectoris or other symptoms raising the suspicion of IHD and non-obstructive epicardial coronary arteries on invasive coronary angiography (ICA, diameter stenosis of less than 50%) with an FFR \>0.80. * Any other clinical scenario (including in the context of ACS) prompting the physician to assess the function of the coronary microvasculature. Exclusion Criteria: * Unable to provide consent * Unstable hemodynamics * Ongoing chest pain. * Previous CABG * Moderate to severe valvular heart disease * Uncontrolled or recurrent ventricular tachycardia. * Active liver disease or hepatic dysfunction, defined as AST or ALT \> 3 times the ULN. * Comorbidity with life expectancy \<= 2 years. * Severe renal dysfunction, defined as an eGFR \<30 mL/min/1.73 m2. * Subject is currently participating in another investigational drug or device clinical study. * Presence of other anatomic or comorbid conditions, or other medical, social or psychological conditions that, in the investigator's opinion, could limit the subject's ability to participate in the clinical investigation or to comply with follow-up requirements, or impact the scientific soundness of the clinical investigation results.