This study has been designed as a randomized, double-blind trial to provide definitive evidence on the effects of ticagrelor and prasugrel on myocardial salvage in patients with anterior ST Segment Elevation Myocardial Infarction (STEMI) undergoing primary Percutaneous Coronary Intervention (PCI). This study will also measure the effects of ticagrelor vs. prasugrel on secondary endpoints listed above. This study design aims to test the hypothesis that ticagrelor will reduce myocardial infarct size as a proportion of the ischemic area at risk when compared to prasugrel.