MGuard™ Prime Embolic Protection Stent in Patients With Acute ST Elevation Myocardial Infarction

Inclusion Criteria: 1. Subject is \>18 years of age. 2. Subject is experiencing clinical symptoms consistent with ST elevation acute myocardial infarction (STEMI) of \>30 minutes and \<24 hours. 3. Based on coronary anatomy, primary PCI is indicated for the culprit lesion with anticipated use of stenting. 4. Subject agrees to all required follow-up procedures and visits and has provided informed consent where required. 5. The target lesion is a de novo lesion in a native coronary artery. 6. The reference vessel diameter (RVD) of the infarct lesion is 2.75-4.0 mm by visual assessment. Exclusion Criteria: 1. Subject undergoing cardiopulmonary resuscitation. 2. Cardiogenic shock (SBP \<80 mmHg for \>30 minutes, or requiring IV pressors or intra-aortic balloon bump (IABP) or other hemodynamic support device for hypotension). 3. Co-morbid condition(s) or others that could limit the subject's ability to participate in the trial or to comply with follow-up requirements, or impact the scientific integrity of the trial. 4. Target lesion involves a bifurcation with a side branch \>/=2.0 mm in diameter. 5. In the Investigator's opinion the lesion/vessel is unsuitable for treatment with the MGuard™ Prime Embolic Protection Stent System for any reason.