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Angiographic thrombus is associated with larger infarct size in ST elevation myocardial infarction (STEMI) population and thrombus aspiration has been shown to improve coronary perfusion in STEMI. In contrast, a recent randomized trial in non-ST elevation myocardial infarction (NSTEMI) population showed thrombus aspiration did not lead to a reduction in microvascular obstruction. We aimed to assess the impact of thrombus on infarct size in NSTEMI population.
We performed a retrospective analysis of 481 consecutive patients with NSTEMI who underwent coronary angiography within five days after presentation. Patients with nonobstructive coronary artery defined as less than 70% stenosis (50% in the left main coronary artery) were excluded. Infarct size was determined as peak cardiac troponin I value. Angiographic thrombus was graded according to Thrombolysis In Myocardial Infarction (TIMI) grade. High-grade and low-grade thrombi were defined as TIMI grade 4-5 and TIMI grade 1-3, respectively. Patent infarct-related artery was defined as TIMI grade 2-3 flow. Clinical and angiographic characteristics, infarct size and in-hospital major adverse cardiac event (MACE) including death, recurrent myocardial infarction, and target vessel revascularization were compared between patients with and without angiographic thrombus.
After excluding 103 patients with nonobstructive coronary artery disease, 378 patients were included in the final analysis. Among 378 patients, 162 (42.9%) patients had angiographic thrombus, of which 71 patients had high-grade thrombus. Peak troponin values were significantly higher in patients with thrombus compared with those without thrombus (median [interquartile]; 3.66 [0.36-13.3] ng/ml vs. 0.69 [0.10-4.36] ng/ml, p<0.001). After excluding patients with TIMI grade 0/1 flow, patients with thrombus had a higher peak troponin (1.53 [0.27-6.83] ng/ml vs. 0.49 [0.10-2.95] ng/ml, p=0.003). Patients with thrombus had a higher rate of in-hospital revascularization (89.5% vs. 68.5%, p<0.001). In the subgroup of the patients who underwent ad-hoc percutaneous coronary intervention (n=217), patients with thrombus had a higher rate of post-procedural TIMI 0 flow (5.5% vs. 0%, p=0.03). There was no significant difference in the rate of in-hospital MACE.
Our study demonstrated that angiographic thrombus was associated with larger infarct size indicated by higher peak troponin values in patients with NSTEMI, even among patients with patent infarct-related artery.