Clinical impact of thrombus burden in patients with ST-segment elevation myocardial infarction

Abstract

The first primary percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction (STEMI) was performed in the early 1980s, and it is now the established and preferred therapeutic option for patients with STEMI [1,2]. Intracoronary thrombus subsequently developed at the site of plaque rupture is the essential mechanism of acute coronary occlusion in STEMI patients, and it is observed in more than 90% of the culprit lesions on the emergency coronary angiography. Thus, the management of residual intraluminal thrombus is very important during primary PCI [3]. Intracoronary thrombus has been characterized on angiography as the presence of a filling defect, and thrombus burden was previously semi-quantified according to the thrombolysis in myocardial infarction (TIMI) thrombus grade (TG 0 to 5) [4]. TIMI TG 0 corresponds to no angiographic evidence of thrombus, whereas TIMI TG 5 corresponds to total occlusion from occlusive thrombus. However, there are many cases whose thrombus size cannot be assessed properly by TIMI TG classification because of no antegrade flow distal to the total occlusion site at the time of initial angiography. Recently, a modified TG classification has been proposed by Sianos and colleagues. In their new algorism, TIMI TG 5 was reclassified into one of the other TIMI TG categories after flow achievement with either guidewire crossing or a small (diameter 1.5 mm) deflated balloon passage or dilation [3]. According to this new classification, most lesions can be classified from TG 0 to 4 and TIMI TG 0-3 are considered a small thrombus burden, whereas TIMI TG 4 is considered a large thrombus burden. In this issue of the Journal, Martí et al.[5] evaluated thrombus burden with this new classification and examined the clinical impact of TG in a systematic primary PCI cohort for the first time. They found that thrombus burden was associated with an increased incidence of angiographic complications and larger infarct size in the acute phase. These findings are consistent with previous studies showing that angiographic evidence of coronary thrombi is a negative prognostic factor of in-hospital adverse cardiac events [3,6]. In fact, intracoronary thrombi can impair both coronary and myocardial perfusion by spontaneous or primary PCI-induced occlusion of an epicardial vessel or its branches or distal embolization of thrombotic components.

The Burden of Short-term Major Adverse Cardiac Events and its Determinants after Emergency Percutaneous Coronary Revascularization: A Prospective Follow-up Study

“…Our study findings were consistent with results of other researches presenting that angiographic evidence of coronary thrombi as a proven indicator of poor hospital course and adverse cardiac events [ 14 ]. In reality, distal embolization of thrombotic constituents or primary PCI-induced or spontaneous occlusion of epicardial vessels might compromise not only coronary but also myocardial perfusion [ 20 ].…”

Determinants of angiographic thrombus burden and impact of thrombus aspiration on outcome in young patients with ST‐segment elevation myocardial infarction

“…Adverse impacts of HTB are well established in previous studies in that HTB is a significant independent predictor for mortality and MACE and the size of the intracoronary thrombus is also associated with worse clinical outcomes, such as no reflow phenomenon, distal embolization, and lower procedural success. 3,31,32 In patients with STEMI, HTB, subsequent distal embolization and myocardial noreflow remain as a large obstacle that may negate the benefits of urgent coronary revascularization. 33 However, none of these studies specifically referred the impact of HTB in young STEMI patients.…”

The predictive value of R wave peak time to detect thrombus burden in st-segment elevation myocardial infarction: a retrospective cohort study in a tertiary medical center

“…Clinical studies demonstrated that intracoronary thrombus challenges periprocedural success regardless of the underlying mechanism. HTB is related to distal embolization, no-reflow microvascular obstruction, inadequate reperfusion, subsequent myocardial damage, and deterioration of ventricular function 5,6,[18][19][20] . However, patients with HTB experience more stent thrombosis, recurrent MI, and recurrent revascularization 17,21 .…”

“…Higher thrombus burden in the course of AMI worsens outcomes both during the procedure and in the long term 5 . Despite the developing interventional techniques and more potent antithrombotic treatments, patients with higher thrombus burden have higher procedural complications such as no-reflow and distal embolism also; these patients have a more extended hospital stay, increased risk of stent thrombosis, recurrent AMI, heart failure (HF) and malignant arrhythmias 6 .…”