Thrombus Grading for Coronary Interventions

The Role of Contemporary Classifications

On Topaz; Allyne Topaz; Kristine Owen


Interv Cardiol. 2011;3(6):705-712. 

In This Article

Abstract and Introduction


A thrombus is an important component of the active and unstable atherosclerotic coronary plaque. A thrombus exhibits unique physical properties and commonly displays profound abnormal vascular behavior. The presence of a thrombus has been recognized as a strong predictor of significant risk for complications and poor outcome in percutaneous interventions and imposes technical challenges regarding its removal from the vasculature. Thus, angiographic detection of a thrombus serves as a procedure hallmark, which requires careful consideration for selection of an appropriate treatment approach. The grading of an underlying thrombus content and its burden on coronary flow can be assessed by various classifications. The aim of this article is to describe the pathophysiologic components of thrombus formation and to delineate the role of corresponding contemporary classifications that can be used for its assessment. Incorporating thrombus classification into the decision-making process in percutaneous coronary revascularization can enhance the yield of procedures and ensure high-quality interventions.


Determining the appropriate management for patients with acute and chronic ischemic coronary syndromes requires careful assessment of the risk of mortality and adverse ischemic events.[1] The morphology of the targeted plaque and its composites needs to be taken into consideration once a decision has been made to proceed with percutaneous coronary intervention (PCI). Thrombus are an integral component of atherosclerotic coronary plaques, which are frequently encountered in patients with unstable angina and acute myocardial infarction (AMI).[2,3] There is a consensus that the presence of intracoronary thrombus constitutes a challenging target for revascularization because of its unique physical properties and pathologic vascular characteristics. Due to the crucial impact of thrombus on the performance and the outcome of PCI, the quest for an optional treatment for thrombotic lesions continues.[4] To date, thrombus remains a strong predictor of PCI-induced major adverse coronary events, development of acute and late stent thrombosis and increased rate of in-hospital complications, as well as AMI and death at 6 months.[5–7] Harjai et al. investigated the incidence of intracoronary thrombus after primary PCI for AMI and analyzed its impact on the presence of residual thrombus post-intervention for acute coronary syndromes.[8] They found that residual thrombus is relatively uncommon; however, in those patients with Thrombolysis In Myocardial Infarction (TIMI) 2 or TIMI 3 flow post-PCI the presence of intracoronary thrombus is associated with worse cardiovascular outcomes.

The response of thrombus to standard management by pharmacotherapy and interventional equipment varies, and at times, is unpredictable. Plausibly, the classification of thrombus according to its burden is warranted because it focuses on one of the most important components, of the active, unstable atherosclerotic plaques. Thrombus classification can also enhance the yield of procedures and ensure high-quality interventions.[9] Intriguingly, despite the understanding of the structural complexity of thrombus[10] and its significant impact on PCI outcome,[11,12] the literature reveals a paucity of publications regarding PCI for ischemic coronary syndromes reporting the presence of angiographic thrombus or grade of its burden.[13] Therefore, the aim of this article is to delineate the pathophysiologic aspects of thrombus formation and to detail the contemporary classifications of thrombus grading.


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