Study Comparing Two Administration Pathways for Adenosine During Microvascular Function Assessment

Inclusion Criteria: * Chronic coronary syndrome (including patients with anginal equivalents). * Indication to cardiac catheterization; * Indication to the assessment of microvascular function (note: patients will be asked for participation and consented prior to the first measurement of microvascular function, which will be conducted as per clinical indication) * Willingness to participate and ability to understand, read and sign the informed consent * Age\>18 years Exclusion Criteria: * Age \<18 years * Bronchial asthma, COPD (chronic obstructive pulmonary disease) * Secondary or tertiary atrioventricular block without prior pacemaker implantation * Previous CABG (coronary artery bypass graft) with patent grafts to the left anterior descending coronary * Epicardial coronary disease (FFR \<0.80 with evidence of a focal stenosis) in the left anterior descending territory * Inability to provide informed consent