The impact of initial and residual thrombus burden on the no-reflow phenomenon in patients with ST-segment elevation myocardial infarction

Background Limited data are available on the clinical significance of residual thrombi after thrombectomy and prestenting reduced epicardial coronary flow in ST-segment elevation myocardial infarct (STEMI) patients. Materials and methods The incidence of the no-reflow phenomenon, defined as a final thrombolysis in myocardial infarction (TIMI) flow grade of up to 2 or a myocardial blush grade of up to 1, was compared in 260 STEMI patients undergoing primary percutaneous coronary intervention according to thrombotic burden. Large thrombotic burden (LTB), defined as a thrombus score of at least 3, was observed in 134 patients, among whom 66 (49.3%) underwent aspiration thrombectomy. No-reflow incidence was compared on the basis of thrombectomy treatment, thrombus residue after thrombectomy, and prestenting TIMI flow grade. Results The no-reflow phenomenon occurred most frequently in LTB patients without thrombectomy, followed by those who underwent thrombectomy and the small thrombus burden group (33.8 vs. 21.2 vs. 10.3%, respectively, P<0.001). Patients with a prestenting residual thrombus or a TIMI flow grade of up to 2 had higher no-reflow incidence than those with no visible prestenting thrombus and a TIMI flow grade of 3 (74 vs. 6.2%, P<0.001). Multiple logistic regression analysis identified a prestenting TIMI flow grade of up to 2 (odds ratio 36.422, 95% confidence interval 13.952-95.079) as an independent predictor of the no-reflow phenomenon. Conclusion Manual thrombus aspiration reduced no-reflow incidence in STEMI patients with LTB. However, even after thrombectomy, prestenting residual thrombi and decreased coronary flow were related to a higher occurrence of the no-reflow phenomenon.