Chapter 11
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The Current Role of Thrombectomy in ST-elevation Myocardial Infarction: Indications, techniques and emerging evidence | |
Kunal Sarkar, MD, Annapoorna S. Kini, MD, FACC, Samin K. Sharma, MD, FACC
The authors report no conflicts of interest regarding the content herein.
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In 1980, De Wood and colleagues1 demonstrated the presence of thrombus in the infarct-related artery (IRA) of 88% of all patients undergoing coronary artery angiography within the first 4 hours of acute myocardial infarction (MI).This landmark study initiated a shift in the management of acute MI, with the use of thrombolytic agents and later, with percutaneous coronary intervention (PCI) for the restoration of coronary artery blood flow. PCI with stent implantation has since been established as the treatment of choice for ST-segment elevation myocardial infarction (STEMI).2,3 The timely re-establishment of coronary blood flow reduces infarct size, enhances myocardial perfusion, attenuates adverse left ventricular (LV) remodeling and reduces longterm mortality. However, successful recanalization of the epicardial vessel may still be accompanied with suboptimal myocardial reperfusion, portending an unfavorable outcome. Distal embolization is believed to be an important determinant in poor tissue reperfusion and is noted in up to 16% of patients undergoing primary PCI for STEMI.4
Preventing embolization of thrombotic and atherosclerotic debris is an attractive strategy to improve myocardial reperfusion and survival after acute MI (Figure 1). Adjunctive antithrombotic therapy with glycoprotein (GP) IIb/IIIa inhibitors5,6 and a multitude of mechanical thrombectomy devices have been evaluated in clinical studies for their role in preventing distal embolization. In addition to their primary role of thrombus removal, these devices may help in better defining the severity of
This discussion will focus on the current patterns for use of mechanical thrombectomy, a description of commonly used thrombectomy devices, and emerging evidence from retrospective analyses and prospective clinical trials regarding optimal patient selection for mechanical thrombectomy. A simplified decision-making algorithm, integrating clinical and angiographic characteristics (thrombus burden), morphologic characteristics of the underlying culprit lesion and our institutional experience with these techniques has been included to provide a useful approach to integrate thrombectomy in routine clinical practice.
The Case for Removing Thrombus
It has been demonstrated that restoration of epicardial coronary blood flow is not synonymous with adequate myocardial tissue perfusion.9,10 Signs of hypoperfusion are frequently encountered after successful primary PCI for acute MI. Impaired microcirculatory perfusion as expressed with tissue myocardial perfusion grade (TIMI grades 0-2) is observed in a majority (66%) of patients who undergo primary PCI with stent implantation, especially without adjunctive IIb/IIIa inhibition (Table 1).This is accompanied with only partial (30-70%) or no (< 30%) resolution of ST segments on...
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