Plaque rupture leads to a cascade of events culminating in collagen disruption, tissue factor release, platelet activation and thrombus formation. Pro-inflammatory conditions, hyperglycemia and smoking predispose to high thrombus burden (HTB) which is an independent predictor of slow or no-reflow. In patients with acute myocardial infarction (AMI), glycoprotein IIb/IIIa inhibitors (GPI) reduce thrombus burden and improve myocardial perfusion. These agents are typically administered systemically via the intravenous route or locally via an intracoronary (IC) route. However, as higher local concentrations of GPI are associated with enhanced platelet inhibition, intralesional (IL) GPI administration may be particularly effective in cases of HTB. Modest-sized randomized trials comparing IL and IC GPI delivery have reported conflicting outcomes. Some trials have demonstrated improved coronary flow and myocardial perfusion with reduced major adverse cardiac events with IL compared with IC GPI administration, whereas others have shown no significant benefits. Furthermore, although no direct comparison has been made between IL delivery using an aspiration catheter, microcatheter or a dedicated balloon-based "weeping" infusion-catheter, improved outcomes have been most consistent following GPI administration at the site of the lesion and thrombus with the dedicated infusion catheter. This review provides an update on the role and outcomes of IL GPI administration in patients with AMI and HTB. Based on the evidence we offer an algorithm demonstrating when to consider IL administration in patients with AMI undergoing intervention. We conclude with a perspective on the management of patients with STEMI and COVID-19 in whom a prothrombotic state often results in HTB.
Keywords: glycoprotein IIb/IIIa inhibitors; intralesional; myocardial infarction.
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