Upstream vs deferred administration of small-molecule glycoprotein IIb/IIIa inhibitors in primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: insights from randomized clinical trials

Short-term effect of upstream administration in comparison to deferred injection of tirofiban on patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

BACKGROUND

High bolus dose tirofiban has been demonstrated to provide greater inhibition of platelet aggregation, but the most appropriate timing of its administration remains unknown.

OBJECTIVES

To evaluate the efficacy of upstream vs. deferred administration of tirofiban in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention (PCI) on clinical outcomes.

METHODS

The 660 patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention were divided into upstream (n=330, administration of tirofiban to all patients in emergency room) and deferred groups (n=330, treatment of patients with large thrombus burden or no-reflow phenomenon in cardiac catheterization laboratory during PCI). The primary end-points were death, nonfatal myocardial infarction (MI), stent thrombosis (ST), revascularization of targeted vessels (TVR) or major adverse cardiac events (MACE) at 1 month and 6 months following PCI, with safety end-point at 7 days.

RESULTS

Compared with that of the deferred group, there was a significant increase of left ventricular ejection fraction (LVEF) in the upstream group within 7 days (55.5 ± 6.6% vs. 54.6 ± 7.9%, P=0.011). The rates of 7-day and 1-month MACE in the upstream group were lower than those in the deferred group (1.5% vs. 4.2%, 3.3% vs. 7.0%, P=0.037 and 0.034, respectively). However, there were higher tendencies for major and minor bleedings in the upstream group (1.8% vs. 0.9%, 2.7% vs. 1.5%, P=0.315 and 0.280, respectively).

CONCLUSION

To the Chinese patients with acute myocardial infarction undergoing primary PCI, upstream administration of tirofiban was slightly superior to deferred injection for short-term clinical outcomes.

Optimal use of platelet glycoprotein IIb/IIIa receptor antagonists in patients undergoing percutaneous coronary interventions

Discovery of the central role of platelets in the pathogenesis of acute coronary syndromes (ACS) and ischaemic complications of percutaneous coronary interventions (PCI) has led to the widespread use of oral and parenteral platelet inhibitors to treat these conditions. Glycoprotein (GP) IIb/IIIa (also known as α(IIb)β(3)) receptors on the surface of platelets play an essential role in platelet aggregation and serve as a key mediator in the formation of arterial thrombus. When activated, GP IIb/IIIa receptors bind to fibrinogen, which serves as the 'final common pathway' in platelet aggregation. Of the numerous agents developed for modulating platelet activity, intravenous platelet GP IIb/IIIa receptor antagonists are the most potent. There are four agents in clinical use, including abciximab, eptifibatide, tirofiban and lamifiban, although lamifiban is not approved for use in the US. While all agents block fibrinogen binding to GP IIb/IIIa, they do so by different mechanisms. Abciximab is a humanized form of a murine monoclonal antibody directed against GP IIb/IIIa, eptifibatide is a synthetic, cyclic heptapeptide that contains a lysine-glycine-aspartic acid (KGD) sequence that mimics the arginine-glycine-aspartic acid (RGD) sequence found on GP IIb/IIIa, tirofiban is a non-peptide antagonist derived by optimization of the tyrosine analogue that structurally mimicks the RGD-containing loop of the disintegrin echistatin, and lamifiban is a synthetic, non-cyclic, non-peptide, low-molecular-weight compound. In clinical trials, use of these agents reduces ischaemic adverse cardiovascular events in patients with ACS undergoing PCI, but at a cost of increased bleeding.

Efficacy of clotinab in acute myocardial infarction trial-ST elevation myocardial infarction (ECLAT-STEMI)

BACKGROUND

This study investigated the efficacy and the safety of the upstream glycoprotein (Gp) IIb/IIIa inhibitor (clotinab; ISU ABXIS, Seoul, Republic of Korea) under 600-mg clopidogrel pretreatment compared with provisional use in ST-elevation myocardial infarction (STEMI).

METHODS AND RESULTS

A total of 786 STEMI patients were randomized to upstream use in the emergency room (ER) (n = 392) or provisional use during percutaneous coronary intervention (PCI) (n = 394). All patients were prescribed 600-mg clopidogrel in the ER. The primary endpoint was the 30-day incidence of composite events including death, nonfatal myocardial infarction, target vessel revascularization, and stroke. There was no significant difference in the events that occurred in 40 patients (10.2%) in the upstream arm and 55 patients (14.0%) in the provisional arm during the 30 days (odds ratio 0.70, 95% confidence interval 0.45-1.08). Major bleeding was higher in the upstream arm (1.5% vs. 0%, P = 0.02). However, there was a significant reduction in 30-day composite events in the upstream arm in the high-risk population (Killip class ≥II or GRACE score >140).

CONCLUSIONS

The upstream use of clotinab under a 600-mg clopidogrel loading may not significantly reduce cardiac events following primary PCI but may improve the clinical outcome in high-risk patients.