A Single Center Diagnostic, Cross-sectional Study of Coronary Microvascular Dysfunction

Inclusion Criteria: * Adult women age ≥18 years referred for coronary angiography * Stable ischemic heart disease, defined by ischemic symptoms and/or myocardial ischemia by stress testing * Administration of aspirin therapy prior to cardiac catheterization Exclusion Criteria: Pre-Cath Exclusion criteria: * Active bleeding and/or bleeding diathesis * Anemia (hemoglobin \<9 mg/dl) * Known thrombocytosis (platelet count \>500,000) * Know thrombocytopenia (platelet count \<100,000) * NSAIDs (e.g., ibuprofen, naproxen) within 3 days * Platelet antagonists other than aspirin and thienopyridines, within 7 days * Prior percutaneous coronary intervention or coronary artery bypass grafting * Acute myocardial infarction within 3 months * Severe valvular heart disease * Cardiogenic shock or mechanical circulatory support * New York Heart Association (NYHA) Functional Class III or IV heart failure * Ejection Fraction \<40% * Hypertrophic obstructive cardiomyopathy or severe left ventricular hypertrophy * Pregnancy * Contraindication to intravenous infusion of adenosine during coronary angiography, due to known hypersensitivity to adenosine, known or suspected bronchoconstrictive or bronchospastic lung disease (severe asthma), second- or third-degree AV block (except in patients with a functioning artificial pacemaker), or sinus node disease, such as sick sinus syndrome or symptomatic bradycardia, Angiographic Exclusion criteria: * Obstructive CAD (≥50% luminal obstruction in ≥1 major epicardial coronary arteries by invasive coronary angiography) * Unfavorable coronary artery anatomy for guidewire positioning (as determined by the angiographer or PI)