Combined intracoronary glycoprotein inhibitors and manual thrombus extraction in patients with acute ST-segment elevation myocardial infarction - Does incorporation of both have a legitimate role?

Abstract

In a substantial number of patients with acute ST-segment elevation myocardial infarction (STEMI), myocardial perfusion at the myocardial cellular level continues to be impaired despite achieving brisk antegrade flow in the infarct-related coronary artery by primary percutaneous intervention. This is attributable to embolisation of the coronary thrombus into the distal vasculature, producing microvascular plugging, vasospasm, interstitial oedema and cellular injury. There is consequently less salvage of infarct size, reduced left ventricular function and poorer clinical outcomes. Glycoprotein inhibitors are the most potent inhibitors of platelet aggregation and have been repeatedly shown to improve clinical outcomes in acute STEMI when administered intravenously. In recent years, randomised trials have demonstrated that glycoprotein inhibitors administered by the intracoronary route are safe and effective in reducing infarct size and providing better clinical outcomes than when given intravenously. Simultaneously, numerous randomised studies using adjunct manual thrombus extraction during primary percutaneous intervention in patients with acute STEMI have shown significantly better ST-segment resolution and myocardial blush grade, suggesting improved myocardial reperfusion, and, more importantly, significant one-year reductions in mortality. However, manual thrombus extraction cannot be used in all patients because there are occasions when the thrombus burden is too large to be aspirated completely or it is impossible to negotiate the thrombus extraction catheter beyond the occlusion. Similarly, glycoprotein inhibitors albeit delivered by the intracoronary route are unable to produce disaggregation of thrombus in all STEMI patients. A small pilot study involving 40 patients with acute STEMI demonstrated that the combination of intracoronary tirofiban and manual thrombus extraction is both safe and effective. However, there are no randomised data on the combined usage of intracoronary tirofiban and manual thrombus extraction in acute ST-elevation and, therefore, it is imperative that large, adequately powered, randomised studies are undertaken to study the synergistic effects of these two modalities. This article describes the various studies that have compared intracoronary glycoprotein inhibitors with the intravenous route and the rationale behind the advantages of manual thrombus extraction in the setting of acute STEMI.