Chapter 12 - Thrombus Classifications: Critical Tools for Diagnostic and Interventional Cardiovascular Procedures

Abstract

Thrombus is frequently encountered in patients with unstable angina pectoris, acute myocardial infarction, and peripheral ischemic conditions. The unique morphologic characteristics and physical properties of the thrombus constantly challenge the performance and outcome of percutaneous coronary and peripheral vascular interventions. As of this writing, thrombus remains a strong predictor of revascularization-induced major adverse coronary events, including distal embolization, “no-reflow” phenomenon, development of acute and late stent thrombosis, increased rate of in-hospital complications, acute myocardial infarction, and death at 6months. Paramount to the management of ischemic cardiac and other vascular thrombotic syndromes is the use of contemporary thrombus classifications. The thrombolysis in myocardial infarction (TIMI) thrombus grading scale is the most commonly applied classification, and it utilizes an angiographic visual score consisting of five distinctive grades. The maximal thrombus burden is defined as TIMI grade 5, which when considering revascularization should undergo a process of restratification and be assigned a specific type. Other classifications are readily available as well for application. A focus on the thrombotic burden as offered by utilization of relevant classifications leads to safer decision-making concerning optimal treatment modalities, desirable revascularization outcomes, and reduced associated risks and complications. Meticulous attention should be given to identification and classification of postintervention residual thrombus as it adversely impacts procedure outcomes. Thus, from a proper patient management perspective, all diagnostic procedures and percutaneous interventions for acute coronary and peripheral ischemic syndromes should classify the thrombus burden within the target lesions and vessels.