Association of Mean Platelet volume With Angiographic Thrombus Burden In Patient With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutanous Coronary Intervention

INTRODUCTION

Despite the improvement in the management of intracoronary thrombus, including intracoronary administration of glycoprotein IIb/IIIa inhibitors, thrombus aspiration and thrombectomy, PPCI for STEMI patients with large intracoronary thrombus burden still carries an increased risk of complications for patients¹.

Because large intracoronary thrombus possesses prognosis importance, it requires early recognition and effective treatment. Thus, establishing preprocedural factors predisposing for thrombus burden is in demand, which may improve risk stratification and provide therapeutic implications in the clinical evaluation of patients with STEMI before PPCI².

Platelets play an important role in cardiovascular disease both in the pathogenesis of atherosclerosis and in the development of acute thrombotic events. Mediators of inflammation, atherosclerosis, coagulation, and thrombosis can be released by platelets. Platelets vary in size and are hemostatic in nature. The larger the platelets in the circulation, the more granules they contain and release higher amounts of prothrombotic and vasoactive factors and undergo rapid aggregation under agonist stimulation³.

Based on their thrombotic potential, platelets have shown a substantial contribution to the pathogenesis of STEMI. Mean platelet volume; a measure of the platelet size has been shown to correlate with platelets’ reactivity⁴.

Coronary artery thrombosis is the final pathogenic mechanism of acute ischemic events, including myocardial infarction and sudden cardiac arrest. There are complex interactions among the atherosclerotic artery, endothelial injury and dysfunction, vasospasm, and platelet activation. Plaque rupture exposes thrombogenic subendothelial components, leading to platelet deposition and activation⁵.

PATIENT AND METHODS

Patient:

This study was conducted on 125 patients admitted to El-Mokatem health insurance hospital, with the diagnosis of acute ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention in the period between December 2018 and October 2019. Inclusion criteria were continuous chest pain for at least 30 minutes within the preceding 12 hours; ECG showing ST-segment elevation 1 mm in two contiguous limb leads or 2 mm in two contiguous precordial leads; new-onset left bundle branch block; and age 18 years. Exclusion criteria were hematologic disorders; and patients with missing admission MPV data and/or follow-up information.

Laboratory analysis and echocardiography:

 In all cases, venous peripheral blood samples were drawn on admission, then collected into standardized tubes containing dipotassium ethylenedinitrotetraacetic acid (EDTA) reagent and stored at room temperature. Complete blood picture including the MPV measurements was performed within 30 minutes of admission. Echocardiography investigation was routinely performed to all patients within 48 hours after PPCI. Left ventricular ejection fraction (LVEF) is measured using both M-mode and 2D eyeballing.

Coronary angiography and intervention:

 Coronary angiography in standardized projections and PPCI was performed for each case. Digital angiograms were then analyzed by an experienced interventional cardiologist who was blind to the MPV results. Intracoronary thrombus was graded as; TIMI thrombus Grade 0 (G0), no cine angiographic characteristics of thrombus are present; TIMI thrombus Grade 1 (G1), a possible thrombus is present, with such angiography characteristics as reduced contrast density, haziness, irregular lesion contour, or a smooth convex “meniscus” at the site of total occlusion suggestive of, but not diagnostic of, thrombus; TIMI thrombus Grade 2 (G2), there is definite thrombus, with greatest dimensions <1/2 the vessel diameter; TIMI thrombus Grade 3 (G3), there is definite thrombus, but with greatest linear dimension >1/2 but 2 vessel diameters; TIMI thrombus Grade 5 (G5), there is total occlusion (unable to assess thrombus burden due to total vessel occlusion).

In TIMI thrombus Grade 5 (G5), we reclassified the thrombus into G0 to 4 after the wire passed the lesion or small size balloon (⁶.

Patients were divided into two groups according to the final TIMI thrombus grade: low-thrombus burden group (LTB) with a grade of 0-3, and high-thrombus burden group (HTB) with a grade of 4&5.

Statistical analysis:

Recorded data were analyzed using the statistical package for social sciences, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed as mean ± standard deviation (SD). Qualitative data were expressed as frequency and percentage. The differences between groups of continuous variables with a normal distribution (age, LVEF, stent parameters, and hematological parameters) were tested by independent samples t-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, HTN, LVEF, creatine level, and hemoglobin level). Multivariate logistic regression analysis was then used to identify independent predictors of high thrombus burden using variables (MPV, time from symptom onset to PPCI, and platelets 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 MPV to predict the high-thrombus burden. A two-sided p-value of < 0.05 was considered significant.

RESULTS

During the study period, 125 patients were enrolled. There were 60 patients (48%) in the HTB group (mean age 59.45 ± 10.79 and 88.3% men), and 65 patients (52%) in the LTB group (mean age 60.28 ± 10.23 and 86.2% men). Baseline clinical characteristics of the study population stratified by thrombus burden are presented in Table I. There is no significant differences were observed for other clinical variables between two groups. Baseline laboratory characteristics of the study population stratified by thrombus burden are summarized in Table II. The admission MPV was significantly higher in the HTB group than in the LTB group (10.42 ± 0.79 vs. 8.88 ± 0.84, P < 0.001). The left anterior descending coronary artery was shown to be the most frequently involved IRA in HTB group compared with the LTB group (53.3% vs. 56.9%). Compared with patients with HTB, pre interventional TIMI < 3 flow was more in patients with HTB with P-value 0.021. As anticipated, thrombus aspiration device was used more frequently in the HTB group versus LTB group (11.7% vs. 1.5%, P 0.028).

Table 1: Baseline Clinical Characteristics of Study Population

Table 2: Laboratory Characteristics of Study Population

The receiver operating characteristics curve of MPV for predicting large thrombus burden was presented in Fig. 1. The area under the ROC curve for MPV was 0.911. The cutoff value for the prediction of HTB was 9.75 Fl. A MPV 9.75 fL predicted HTB with 83.3% sensitivity and 86.2% specificity.

Fig. 1: ROC curve analysis of admission MPV for angiographic large thrombus burden

When we divided patients into two groups based on the MPV cutoff value of 9.75 fL identified in receiver operating characteristics curve analysis, patients with MPV  9.75 fL had a higher prevalence of no-reflow (6.8% vs. 0.0%, P 0.047) compared with patients with MPV < 9.75 fL Fig. 2.

Fig. 2: correlation of MPV and no-reflow of the study population