[Study on the procoagulant characteristics of microparticles in acute myocardial infarction].

Objective: To investigate the characteristic of circulating microparticle in patients with acute myocardial infarction (AMI) and its possible mechanism of promoting coagulation.

Methods: A prospective case-control study was conducted. The patients with coronary heart disease admitted to the second department of cardiology in Harbin First Hospital from June to November 2023 were enrolled, and they were grouped according to whether the patients occurred AMI or not. On the day of admission, disseminated intravascular coagulation (DIC) score was calculated. At the same time, fasting venous blood was collected, and the levels of D-dimer, fibrin degradation product (FDP) and the activities of major coagulation factors were detected. The level of circulating microparticle was determined by microparticle trapping method. The microparticle carrying tissue factor (TF⁺MP) level was detected by tissue factor (TF) dependent F Xa production assay. Spearman correlation method was used to analyze the correlation among the indicators.

Results: A total of 52 patients with coronary heart disease were enrolled, including 26 patients in AMI group and 26 patients in non-AMI group. There was no significant difference in gender, age, body mass index (BMI), underlying diseases, smoking history, and pre-admission treatment of patients between the two groups, indicating that the baseline data of the two groups were balanced and comparable. Compared with the non-AMI group, the DIC score and D-dimer, FDP levels in the AMI group were significantly increased [DIC score: 3 (3, 4) vs. 3 (2, 3), D-dimer (mg/L): 8.80 (6.84, 15.66) vs. 2.13 (1.64, 3.86), FDP (mg/L): 30.13 (19.30, 52.54) vs. 20.00 (13.51, 28.37), all P < 0.01], indicating that the degree of coagulation activation in AMI patients was more severe. The consumption of major coagulation factors in the coagulation pathway in the AMI group was heavier than that in the non-AMI group [F II: 59.45% (49.65%, 71.25%) vs. 63.65% (49.98%, 73.22%), F V: 96.95% (73.50%, 112.78%) vs. 105.05% (73.48%, 131.48%), F VII: 42.30% (36.98%, 51.98%) vs. 53.40% (46.58%, 69.88%), F X: 60.90% (48.22%, 80.82%) vs. 73.50% (56.80%, 85.98%), F XI: 82.45% (62.90%, 99.10%) vs. 92.40% (73.90%, 114.25%), F XII: 29.90% (12.42%, 42.38%) vs. 34.65% (16.32%, 48.20%), all P < 0.05]. The circulating TF⁺MP level in the AMI group was significantly higher than that in the non-AMI group [nmol/L: 0.13 (0.06, 0.20) vs. 0.08 (0.04, 0.15), P < 0.05]. There was no significant difference in the level of circulating microparticle between AMI group and non-AMI group [nmol/L: 1.24 (0.71, 3.77) vs. 1.35 (0.73, 2.14), P > 0.05]. Correlation analysis showed that circulating TF⁺MP level in the patients with coronary heart disease was significantly positively correlated with coagulation indicator DIC score (r = 0.307, P = 0.027), D-dimer (r = 0.696, P < 0.001) and FDP (r = 0.582, P < 0.001), and there was a strong negative correlation with exogenous pathway factor F VII (r = -0.521, P < 0.001) and common pathway factor F X (r = -0.332, P = 0.016).

Conclusions: The circulating TF⁺MP level in AMI patients was significantly higher than that in the non-AMI patients. TF⁺MP may play an important role in activating the extrinsic coagulation pathway, exacerbating coagulation factor consumption, and promoting clot formation during AMI occurrence.