Assessment of Coronary Flow Reserve by Doppler Flow Wire in Patients With Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention Differences Between the Loading Dose of Ticagrelor and Clopidogrel

The administration of these drugs is realized according to the European Society of Cardiology guidelines. All patients will be pretreated with aspirin 300 mg orally, heparin iv to maintain an activated clotting time of \>250 sec, and a loading dose of ticagrelor (180 mg) or clopidogrel (600 mg) immediately before the revascularization. The list of assignment to ticagrelor or clopidogrel will be generated by a computer according to a 1:1 randomization. Primary Percutaneous Coronary Intervention will be performed according to standard clinical practice using femoral or radial artery Judkins approach via six or seven French heath insertion. After crossing the target occlusive Lesion, coronary stenting will be performed based on standard practice. Patients subsequently will receive heparin for 48 hr, aspirin 100 mg daily, and clopidogrel (75 mg/day) or ticagrelor (90 mg twice daily) for at least 12 months. Other adjunctive pharmacotherapy in Intensive Care Unit will be administered according to operator discretion. All patients will provide written informed consent before entering the study. Before and after the procedure a 12-leads ECG and an echocardiogram will be performed as standard practice. Then, all the pre-, intra-, and post-procedure data patients will be collected in a database. Investigators aim to perform a prospective, single-center, investigator-initiated, randomized study to compare the Adenosine-induced coronary vasodilatation after the loading dose of Ticagrelor either Clopidogrel during the Percutaneous Coronary Intervention. Patients with Acute Coronary Syndrome undergoing Percutaneous Coronary Intervention will be enrolled in the study and will be randomized, in a 1:1 ratio, to receive a loading dose of Ticagrelor (180 mg) or Clopidogrel (600 mg). Coronary Flow Reserve will be recorded by intracoronary Doppler Flow Wire before the stent implantation and after the procedure at baseline and 2-minute later adenosine intravenous administration at inc