Thrombus burden quantification: an evolving tool for coronary interventions

Thrombus is a distinctive histo-pathological feature of patients presenting with STelevation myocardial infarction (STEMI) and constitutes an adverse finding that significantly affects interventional management. Characterization and quantification of coronary thrombi have been a challenge since the beginning of thrombolysis era. Almost 20 years ago, the Thrombolysis in Myocardial Infarction (TIMI) group developed an angiographic thrombus scoring system, relating the maximum thrombus length to the reference vessel diameter. These investigators described 6 thrombus grades (G0 to G5), assigning grade G5 to complete total occlusions [1]. Once the safety and effectiveness of coronary stenting in thrombus containing lesions was proven [2], several investigations consistently demonstrated an association between thrombus burden (TB) and tissue perfusion parameters. However, most of these early studies lacked statistical power to evaluate late clinical outcomes [3].