Adjunctive, Low-Dose tPA in Primary PCI for STEMI

Eligibility Details: Inclusion Criteria: 1. Patients with STEMI undergoing primary PCI and, 2. ECG changes indicating large territory STEMI (defined as ≥2mm ST-segment elevation in 2 contiguous anterior precordial leads; or ≥2mm ST-segment elevation in 2 inferior leads coupled with ST-segment depression in 2 contiguous anterior leads for a total ST-segment deviation of ≥8mm) and, 3. Randomization within 6 to 12 hours of symptom onset and, 4. Large thrombus burden with angiographic TIMI Thrombus Grade ≥3 after guidewire crossing. Exclusion Criteria: 1. Active internal bleeding or high risk of bleeding or any prior intracranial bleeding. 2. Any other absolute or relative contraindication to fibrinolytic therapy. 3. Administration of a fibrinolytic ≤24hrs prior to randomization. 4. Cardiogenic shock on presentation. 5. Left bundle branch block (excluded because the ECG cannot be evaluated for ST segment resolution, an outcome of the study). 6. Planned upfront use of a glycoprotein IIb/IIIa inhibitor. 7. Any medical, geographic, or social factor making study participation impractical or precluding 1 month follow-up.