Prevention of Coronary Microvascular Dysfunction Post-PCI by Intracoronary Nicardipine

Inclusion Criteria: * Consenting adults age \> 18 years * Patients with stable coronary disease, stable angina, and/or objective evidence of myocardial ischemia OR * Target vessel lesion with \> 50% stenosis treated by PCI Exclusion Criteria: * Patients presenting with ST elevation myocardial infarction * Complete total occlusion of the vessel * Unprotected left main disease * Presentation with acute coronary syndrome and actively rising troponin * Contraindication to adenosine (advanced heart blocks, bronchospasm, HSN to the drug) * Known hypersensitivity to nicardipine * Severe aortic stenosis * Left Ventricular dysfunction with ejection fraction less than 30% * Hemodynamically unstable defined as systolic blood pressure \< 90 mmHg and not responding to IV fluids * Significant chronic renal insufficiency (Glomerular filtration rate \[GFR\] \<30) * Unwilling or unable to provide informed consent