Impact of Ranolazine on Coronary Microcirculatory Resistance

Inclusion Criteria: * \- Patients with subjective symptoms of ischemia without flow limiting angiographic CAD (\<50% epicardial coronary stenosis) and abnormal IMR (\>20 U). * Definition of ischemia (any one): * chest pain with dynamic ischemic ECG changes (t wave inversions or \> 1 mm ST depressions * Exercise treadmill testing induced chest pain with ≥1 mm of downsloping or flat ST segment depression during exercise or recovery; ≥2 mm of ischemic ST depression at a low workload (stage 2 or less or ≤130 beats/min); early onset (stage 1) or prolonged duration (\>5 min) of ST depression; multiple leads (\>5) with ST depression * Nuclear stress perfusion defect \> 10% * Stress echocardiogram with stress induced wall motion abnormality Exclusion Criteria: * \- Age \< 18 yrs * Flow Limiting epicardial CAD \>50% * Life expectancy \< 6 months * Recent (\<1 week) myocardial infarction or positive biomarkers * Severe aortic stenosis * Contraindications to IMR testing including inability to utilize antithrombotic therapy and/or intravenous adenosine * Contraindications to Ranolazine therapy: * Patients with known hepatic insufficiency, prolonged QT or renal failure (GFR \< 60) * use of drugs that inhibit CYP3A such as diltiazem, verapamil, ketoconazole, macrolides and HIV protease inhibitors * Pregnancy, breastfeeding * Patients taking drugs which prolong QT interval