Intracoronary Thrombus and Platelet Glycoprotein IIb/IIIa Receptor Blockade With Tirofiban in Unstable Angina or Non–Q-Wave Myocardial Infarction

Abstract

for the PRISM-PLUS InvestigatorsBackground-The present study describes the effects of tirofiban, a nonpeptide platelet glycoprotein (GP) IIb/IIIa receptor blocker, on the characteristics of culprit lesions in patients with unstable angina (UA) or non-Q-wave myocardial infarction (NQWMI). Methods and Results-Of 1915 patients enrolled in PRISM-PLUS, 1491 had a readable film obtained a median of 65 hours after randomization. A core laboratory examined the culprit lesions for intracoronary thrombus burden (primary end point) and for TIMI flow grade distribution and severity of the obstruction and of underlying coronary artery disease (secondary end points). The combination of tirofiban plus heparin compared with heparin alone significantly reduced the intracoronary thrombus burden of the culprit lesions (ORϭ0.77, Pϭ0.022), improved the perfusion grade (ORϭ0.65, Pϭ0.002), and decreased the severity of the obstruction (Pϭ0.037), but it did not influence the severity of the underlying plaque. Persistence of a thrombus in 45% of patients was associated with a 2.4-fold increase in the odds of death at 30 days (Pϭ0.005) and a 2-fold increase in the odds of myocardial infarction (Pϭ0.002). Conclusions-The addition of tirofiban to heparin reduced the thrombus burden of the culprit lesion and improved distal perfusion in patients with UA or NQWMI, which supports the clinical benefit observed with the combination treatment.

Impact of an Audit Program and Other Factors on Door‐to‐balloon Times in Acute ST‐elevation Myocardial Infarction Patients Destined for Primary Coronary Intervention

“…26 The combination of a glycoprotein IIb ⁄ IIIa inhibitor plus heparin significantly reduces the intracoronary thrombus burden of the culprit lesions, improves the perfusion grade, and decreases the severity of the obstruction in patients with unstable angina or non-Q-wave MI. 27 We speculated that the association between use of glycoprotein IIb ⁄ IIIa inhibitors and shorter door-to-balloon time might originate from the facilitation in the clot dissolution, thereby hastening the passage of guide wires through the culprit lesions during PCI. Presentation at off-hours is a strong predictor of a prolonged door-to-balloon time in United States.…”

Effect of Adjunctive Tirofiban Therapy on Angiographic and Clinical Outcomes in Patients With ST-segment Elevated Acute Myocardial Infarction Undergoing Primary Stenting

“…15,16) Another recent randomized clinical trial, the PRISM-PLUS trial 17) demonstrated that the addition of tirofiban to heparin reduced the thrombus burden in the culprit lesion and improved distal perfusion in patients with unstable angina or non-Q-wave myocardial infarction. However, we could find no data on a combination of tirofiban and primary stenting for treatment of ST-segment elevated (ST-se) AMI.…”

“…Therefore, it has been suggested that incremental antiplatelet therapy by GP IIb/IIIa receptor blockers might attenuate the formation of a new platelet-rich thrombus and thereby improve the outcome of primary PCI. 7,15,16) Recently, the PRISM-PLUS clinical trial 17) reported that the addition of tirofiban to heparin reduced the thrombus burden of the culprit lesion and improved distal perfusion in patients with unstable angina or non-Q-wave myocardial infarction. However, our present study demonstrated that compared with primary stenting alone, a combination therapy of early administration of tirofiban and primary stenting for treatment of ST-se AMI did not provide additional benefits for normal coronary blood flow in the IRA, in reducing major cardiac events 7,15,16,19,20) The short-term clinical outcomes of primary PCI have been improved by adjunctive pharmacologic therapy with abciximab.…”

“…This hypothesis, derived from clinical observation, was supported by the TIMI 14 substudy 24) and PRISM-PLUS clinical trial. 17) These two studies demonstrated that adjunctive therapy with abciximab 24) in patients with AMI resulted in only partial lysis of the thrombus, and adjunctive tirofiban therapy 17) in patients with unstable angina or non-Q-wave myocardial infarction usually resulted in residual thrombus in the large right coronary artery. Recently, using quantitative and immunohistochemical analysis of intracoronary thrombus aspirated by a Rescue TM PT catheter in patients with AMI, Fujii and associates showed that more than 70% of the surface area of high burden intracoronary thrombus consists of red blood cells and more than 70% of the surface area of low burden intracoronary thrombus consists of platelets.…”

Comparison of Immediate vs Early Invasive Strategy in Patients With First Acute Non–ST‐Elevation Myocardial Infarction

“…immediate (<6 hours) or early (≤72 hours). 3 Early CA with upstream glycoprotein (GP) IIb/IIIa inhibitors is associated with a reduction in intracoronary thrombus burden 4,5 and improvement in myocardial tissue-level perfusion. 6 On the other hand, immediate CA may reduce the bleeding risk related to GP IIb/IIIa inhibitor therapy, and in a randomized trial this strategy in the setting of non-ST-elevation ACS was associated with a better outcome.…”