Safety of Ticagrelor Monotherapy After Primary Percutaneous Coronary Intervention for ST-elevation Myocardial Infarction and the Effect on Intramyocardial Haemorrhage

Inclusion Criteria: * Clinical and electrocardiographical diagnosis of STEMI * Successful PCI (according to the treating physician) of the infarct-related vessel with a modern drug-eluting stent (DES) Exclusion Criteria: * Known allergy or contraindication for aspirin, ticagrelor or prasugrel. * Previous PCI or MI less than 12 months ago * Previous cardiac surgery * Participation in another clinical cardiology study or study concerning platelet aggregation/ thrombosis. (unless the antithrombotic therapy prescribed in this other study will end due to clinical reasons (e.g. the STEMI)) * Pregnancy and breast feeding * Concurrent use of oral anticoagulants (OAC) * The periprocedural use of GPIIb/IIIa inhibitors * Planned surgical intervention within 12 months of PCI * Creatinine clearance \<30mL/min or dialysis * PCI of stent thrombosis * Suboptimal stent result as judged by the interventional cardiologist. * Life expectancy shorter than 13 months. * Contra-indications for MRI or unable to undergo MRI (only applicable for the CMR subgroup population).