Upstream High-Dose Tirofiban Does Not Reduce Myocardial Infarct Size in Patients Undergoing Primary Percutaneous Coronary Intervention: A Magnetic Resonance Imaging Pilot Study

Background: Primary percutaneous coronary intervention (PCI) is more effective than fibrinolytic therapy for ST-segment elevation myocardial infarction (STEMI), but initial treatment delay to intervention is the main limitation of this strategy. Hypothesis: Upstream use of high-dose tirofiban could reduce myocardial infarct size, using analysis of contrast-enhanced magnetic resonance imaging (CE-MRI). Methods: Patients with STEMI within 12 hours after symptom onset were randomized to a facilitated PCI group (n = 19) or to a primary PCI group (n = 20). The primary endpoint was myocardial infarct size evaluated by the volume of delayed hyperenhancement on CE-MRI at 1 month after index procedure. Results: The baseline clinical characteristics were not significantly different between the 2 groups. Although the incidence of pre-PCI thrombolysis in myocardial infarction (TIMI) flow grade 2 to 3 was significantly higher in the facilitated PCI group than in the primary PCI group (47.4% vs 15.0%, P = 0.03), the achievement of myocardial blush grade 2 to 3 or ST-segment resolution at 30 minutes after procedure was not significantly different between the facilitated PCI and the primary PCI group (36.8% vs 40%, P = .84 and 31.6% VS 20%, P = 0.41, respectively). Infarct size on CE-MRI was similar in the facilitated PCI group and the conventional primary PCI group (22.1% +/- 11.7% vs 25.2% +/- 13.2%, P = 0.44). At 6 months, the left ventricular ejection fraction (LVEF) on echocardiography was 52.6% +/- 10.4% in the facilitated PCI group and 50.9% +/- 9.8% in the primary PCI group (P = 0.68). Conclusion: Despite the improvement of initial TIMI flow grade, the upstream use of high-dose tirofiban did not reduce myocardial infarct size measured by CE-MRI.