Management of the thrombotic lesion
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Associate Editors-In-Chief: Verun Khanna, M.D.; Anthony Smeglin, M.D.; Brian C. Bigelow, M.D.
Goals of Treatment
There are several main goals in treating thrombotic lesions, including:
- Reperfusion of the epicardial artery and the downstream microvasculature
- Resolution/reduction of thrombus burden
- Avoid/minimize distal embolization
- Avoid/reduce thrombotic major adverse cardiac events (death, MI, recurrent ischemia, urgent target vessel revascularization (TVR))
Treatment Choices
Pharmacologic Therapy
- Antiplatelet therapy: Aspirin, platelet glycoprotein IIb/IIIa receptor (GP IIb/IIIa) antagonists (abciximab, eptifibatide, tirofiban), ADP receptor/P2Y12 inhibitors (plavix, ticagrelor, prasugrel)
- Antithrombin Therapy: Ufractionated heparin (UFH), low molecular weight heparin (LMWH). Fondaparinux is not recommended in primary PCI.
- Direct Thrombin Inhibitors: Hirudin, bivalirudin, argatroban
- Thrombolytic Therapy: Urokinase (UK), tissue plasminogen activator (tPA) for STEMI when other pharmacologic and mechanical treatments are not successful
Mechanical Therapy
- Aspiration Catheter: (Export, Pronto) is the choice prior to the other interventions listed below
- Percutaneous Coronary Intervention (PCI): Bare metal or drug-eluting stent particularly direct stenting without pre-dilation by conventional balloon angioplasty
- Distal Protection: (Percusurge guardwire, Triactive, Spider wire, Proxis) particularly in saphenous vein grafts
- Directional Atherectomy
- Transluminal Extraction Catheter (TEC)
- Rheolytic Thrombectomy (Possis Angiojet)
Advantages of Each Choice
- Aspirin is a conventional therapy that reduces ischemic complications after PCI.
- GP IIb/IIIa antagonists are used adjunctively to treat and prevent thrombus formation and decreases ischemic complications post-PCI in patients with angiographic evidence of or suspected thrombus. In patients with STEMI undergoing primary PCI, GP IIb/IIIa antagonists have been shown to reduce mortality in meta-analyses. There is an ongoing debate as to the optimal timing of their administration (upstream vs in lab administration).
- UFH is a conventionally used thrombin inhibitor that prevents arterial thrombus formation at the site of a vessel wall injury, on catheters, and on equipment during PCI.
- LMWH: ExTRACT-TIMI 25 demonstrated that in patients with STEMI undergoing fibrinolysis and subsequent PCI, there was improved clinical outcomes with LMWH.
- Direct thrombin inhibitors (DTI) may be used as alternative to heparin and GP IIb/IIIa. The optimal strategy is to pre-load with clopidogrel if a DTI is used. Drug of choice in patients with a history of heparin-induced thrombocytopenia.
- Thrombus aspiration is the preferred treatment and has been associated with improved myocardial perfusion and mortality. Care should be exercised in very proximal lesions in the LAD and the circumflex as the clot may embolize into the other artery.
- After aspiration, direct stenting is associated with improved rates of recurrent MI in meta-analyses, improved myocardial perfusion and improved ST segment resolution. Stenting reduces the risk of abrupt closure.
- Rheolytic thrombectomy with Possis Angiojet was not found to have benefit in the setting of STEMI in native coronary arteries in the AIMI trial. Infarct sizes were larger and mortality was higher.
- Distal protection
- Occlusive (Percusurge guardwire, Triactive) and filter (Filterwire) methods may improve safety and efficacy of PCI in patients w/ thrombotic lesions in SVG; SAFER study of Percusurge device demonstrated lower rate of death/MI
- Distal embolic protection has not shown to be efficacious in the setting of STEMI in native coronary arteries with either Percusurge (EMERALD trial) or Filterwire (PROMISE trial).