ABC | Volume 110, Nº4, April 2018

Original Article Wang et al Monocyte count and thrombus burden Arq Bras Cardiol. 2018; 110(4):333-338 September 2013 and May 2016 at the Cardiology Department of Beijing Shijitan Hospital. STEMI was defined as: typical chest pain > 30 minutes with ST elevation of > 1 mm in at least two consecutive leads on the electrocardiogram, or new onset left bundle branch block and more than two-fold increase in serum cardiac markers. Exclusion criteria included cardiogenic shock on admission, active infections, systemic inflammatory disease history, known malignancy, liver disease, as well as renal failure. The study protocol was approved by the Beijing Shijitan Hospital Ethics Committee, Capital Medical University, and written informed consent was obtained from patients. Coronary angiography and PCI procedure Pharmacological treatment of all enrolled patients before PPCI included aspirin (300 mg loading dose), clopidogrel (600 mg loading dose) and an intravenous bolus of unfractionated heparin at a dose of 70 U/kg of body weight. PPCI was performed using the standard radial or femoral approach with a 6-or 7-French guiding catheter. The stent was deployed in all patients. The use of balloon pre-dilatation or post-dilatation, the type of stents (bare metal or drug-eluting), and the use of thrombus aspiration was left to the operator’s decision. The glycoprotein IIb/IIIa receptor inhibitor tirofiban was given by judgment of the operator and initiated during PCI procedure with 10 μg/kg intracoronary bolus followed by 0.15 μg/kg/min intravenous infusion. Technically successful stent implantation was defined as the residual stenosis < 10% in the culprit lesion after the procedure as visually assessed by angiography, without occlusion of a significant side branch, flow-limiting dissection, distal embolization, or angiographic thrombus. To evaluate the intracoronary thrombus burden we performed TIMI thrombus scale 4,5 in all patients after ante‑grade flow achievement through guide wire crossing or small balloon dilatation (final TIMI thrombus grade). In TIMI thrombus grade 0, no cine-angiographic characteristics of thrombus are present; in TIMI thrombus grade 1, possible thrombus is present with such angiographic characteristics as decreased contrast density, haziness, irregular lesion contour, or a smooth convex “meniscus”at the site of total occlusion suggestive, but not diagnostic of thrombus; in TIMI thrombus grade 2, there is definite thrombus, with the largest dimensions ≤ 1/2 the vessel diameter; in TIMI thrombus grade 3, there is definite thrombus with the largest linear dimension > 1/2 but < 2 vessel diameters; in TIMI thrombus grade 4, there is definite thrombus, with the largest dimension ≥ 2 vessel diameters; and in TIMI thrombus grade 5, there is total occlusion. Patients were divided into two groups according to the final TIMI thrombus grade: low‑thrombus burden group with a grade of 0–2, and high‑thrombus burden group with a grade of 3–4. Laboratory analysis and echocardiography In all patients, blood samples for measurements were performed according to our previous work. 3 White blood cell (WBC) count, monocyte count, and other biochemical parametersweredrawn into standardethylenediaminetetraacetic acid (EDTA) containing tubes on admission in the emergency room before the administration of aspirin and clopidogrel. Common blood counting (CBC) parameters were measured by an automated blood cell counter (XS-1000i; Sysmex Co.). Creatinine and cardiac enzymes were also measured in all patients determined by the standardmethods. Echocardiography investigation was routinely performed on admission before PPCI, using GE ViVidE7 ultrasound machine (GE Healthcare, America) with a 3.5-MHz transducer. Left ventricular ejection fraction (LVEF) was measured by Simpson’s method in the 2-dimensional echocardiographic apical 4-chamber view. Statistical analyses Statistical analysis was performed by using the SPSS 22.0 Statistical Package Program for Windows (SPSS Inc., Chicago, IL, USA). Continuous variables are presented as a mean ± standard deviation or as medians and interquartile ranges. The differences between groups of continuous variables with a normal distribution (age, LVEF, creatinine, stent parameters and hematological parameters) were tested by independent samples t-test, while skewed distribution variable (peak cardiac troponin I (cTnI)) were compared by the Mann-Whitney U test. Categorical variables were summarized as percentages and compared with the chi‑square test. A univariate analysis was first performed to test for the association of the high-thrombus burden and several potentially impacting variables (age, sex, history of diabetes mellitus, prior myocardial infarction (MI), LVEF, creatine level, time from symptom onset to PPCI, monocyte count, neutrophil count, lymphocyte count and hemoglobin level). Multivariate logistic regression analysis was then used to identify independent predictors of high thrombus burden using variables (prior MI, time from symptom onset to PPCI and monocyte count) that reached a trend-level effect (p < 0.1) in the univariate analyses. The receiver operating characteristics (ROC) curve was used to determine the cut-off value of monocyte count to predict the high-thrombus burden. A two-sided p-value of < 0.05 was considered significant. Results A total of 273 patients (mean age 62.2 ± 13.6 years; 81.0% male) who underwent PPCI were enrolled in our analysis. Stent implantation was technically successful in all patients. The comparison of baseline clinical and laboratory characteristics between thrombus burden groups are presented in Table 1. There were no significant differences between the low thrombus group and the high thrombus group in the age, sex distribution, hypertension, diabetes mellitus, hyperlipidemia, current smoking, prior MI left ventricular ejection fraction and serum creatinine level. Compared with patients with low thrombus burden, patients with high-thrombus burden had higher peak cTnI. Comparison of the baseline angiographic and procedural characteristics of the groups based on thrombus burden is shown in Table 2. Thrombus aspiration device and intracoronary tirofiban administration were used more frequently in the high thrombus burden group than low‑thrombus burden group (62.1 vs. 10.1%, p = 0.000, 83.2 vs. 52.2%, p = 0.000, respectively). There were no significant differences of the time from pain to intervention, infarct‑related coronary artery and other procedural characteristics between two groups. 334