Heart Attack Research Program- Imaging Study

Inclusion Criteria: * Acute ischemic symptoms compatible with diagnosis of MI, such as chest pain or anginal equivalent symptoms at rest or new onset exertional anginal equivalent symptoms * Objective evidence of MI (either or both of the following): * Elevation of troponin to above the laboratory upper limit of normal * ST segment elevation of ≥1mm on 2 contiguous ECG leads * Willing to provide informed consent and comply with all aspects of the protocol * Age ≥ 21 years Exclusion Criteria: * Stenosis ≥50% of any major epicardial vessel on invasive angiography, as determined by the angiographer at the time of clinically ordered cardiac catheterization * History of known obstructive coronary artery disease at angiography, including history of percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) * Recent use of vasospastic agents, such as cocaine, triptans, or ergot alkaloids (≤1 month) * Alternate explanation for troponin elevation, such as hypertensive urgency, acute exacerbation of heart failure, chronic elevation due to kidney disease, pulmonary embolism, cardiac trauma * Coronary dissection apparent on angiography * Excessive coronary tortuosity which, in the angiographer's opinion, increases the risks of OCT * eGFR\<45 or contraindication to additional contrast needed for OCT in the opinion of the angiographer or treating physician * Contraindication to MRI (including but not limited to ferromagnetic implants) * Pregnancy * Thrombolytic therapy for STEMI (qualifying event)