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Keywords:

  • corrected TIMI frame count;
  • glycoprotein IIb/IIIa inhibitors;
  • high bolus dose tirofiban;
  • thrombus burden;
  • primary percutaneous coronary intervention;
  • ST-segment elevation myocardial infarction

Abstract

Objectives: Aim of this study was to assess the effect of early initiation of high bolus dose tirofiban on top of dual antiplatelet therapy on angiographic outcome before and after primary percutaneous coronary intervention (PCI) in ST-elevation myocardial infraction patients. Background: Glycoprotein IIb/IIIa inhibitors are effective inhibitors of platelet aggregation, and have shown to reduce thrombotic complications in patients undergoing PCI. Methods: This is a pre-specified angiographic analysis of the On-TIME 2 trial (N = 984) and its open label run-in phase (N = 414). All angiographic parameters, including quantitative coronary angiography (QCA) were performed in an independent angiographic core lab. Results: Of the 1,398 patients, 709 patients (50.7%) were randomized to pre-hospital tirofiban. An open infarct related vessel (TIMI 2 or 3 flow) at initial angiography was more often present in the tirofiban group as compared to the no tirofiban group (58.3% vs. 49.7%, P = 0.002). Tirofiban also reduced initial thrombus burden (P for trend = 0.035) as well as thrombus grade 5 (46.9% vs. 54.3%, P = 0.016) and showed a trend toward a reduction in large thrombus burden (LTB) (69.4% vs. 74.5%, P = 0.055). After PCI, a trend towards a lower corrected TIMI frame count (cTFC) in the tirofiban group was found. A significant interaction was found with time of initiation of study drug, with highest efficacy of tirofiban when given within 76 min after symptom onset, with a significantly lower cTFC after PCI (21.9 ± 17.6 vs. 23.9 ± 18.5, P = 0.008, P for interaction P = 0.006). Conclusion: In patients undergoing primary PCI, pre-hospital administration of tirofiban reduces initial thrombus burden and improves initial patency of the infarct related vessel before PCI. Initiation of tirofiban seems to be most effective when given very early after the onset of symptoms; however, this finding needs confirmation in other studies. Clinical trial registration: The On-TIME 2 trial is registered, at http://isrctn.org, number ISRCTN06195297. © 2011 Wiley Periodicals, Inc.