[Dynamic changes of complement level in patients with acute coronary syndrome and its relationships with myocardial...

To study relationships between myocardial injury and the levels of serum complement C3, C4 and C5b-9 in patients with acute coronary syndrome (ACS).

A retrospectively analysis was conducted. 170 ACS patients [including 110 cases of ST-segment elevation myocardial infarction (STEMI) and 60 cases of non-ST-segment elevation acute coronary syndrome (NSTE-ACS)] with ischemic chest pain or chest discomfort onset within the prior 12 hours admitted to the cardiology department of Tianjin Union Medicine Center from January 2014 to July 2016 were enrolled. Thirty-six healthy cases were enrolled as control during the same time. The levels of serum complement C3, C4 and C5b-9 on 1, 3 and 7 days after admission and myocardial function indicators were analyzed. Major adverse cardiovascular events (MACE) and readmission rate were analyzed after 1 year follow-up. The correlation between serum complement levels and myocardial function indicators was analyzed by Pearson correlation analysis.

(1) The levels of serum C3, C4 and C5b-9 on the first day in NSTE-ACS group and STEMI group were significantly higher than control group [C3 (g/L): 1.04±0.33, 1.26±0.35 vs. 0.39±0.21, C4 (g/L): 0.31±0.14, 0.33±0.10 vs. 0.19±0.07, C5b-9 (g/L): 575.46±197.26, 659.26±160.77 vs. 501.40±141.51, all P < 0.05]. There were no changes of serum C3, C4 in NSTE-ACS group, but C5b-9 decreased after a peak (g/L: 700.63±218.42) at 3 days. Serum complements in STEMI group reached peak on the third day [C3 (g/L): 1.37±0.33, C4 (g/L): 0.42±0.12, C5b-9 (g/L): 754.72±136.22]. The levels of serum C4 and C5b-9 in STEMI group were higher than NSTE-ACS group on the third and seventh day. (2) The levels of troponin T (TnT), creatine kinase-MB (CK-MB), solution intercellular adhesion molecule-1 (sICAM-1), global registry of acute coronary events (GRACE) scores and percutaneous coronary intervention (PCI) numbers in STEMI group were significantly higher than those in the NSTE-ACS group, which were as opposite as left ventricular ejection fraction (LVEF). However, there were no significant differences in levels of serum N-terminal pro-brain nitric peptide (NT-proBNP), Fibrinogen (Fib), readmission rate and incidence of MACE between STEMI and NSTE-ACS groups. (3) According to GRACE, patients with ACS were divided into low risk group (≤ 108 scores, 26 cases), intermediate risk group (109-140 scores, 61 cases) and highest group (> 140 scores, 83 cases). TnT and sICAM-1 in intermediate risk group were significantly increased as compared with low risk group. Levels of TnT, sICAM-1, C3, C4 and C5b-9 in the highest group were significantly higher than the low and intermediate risk groups, however the lowest LVEF was found in the highest group. (4) It was shown by Pearson correlation analyses that levels of serum C3, C4, C5b-9 were positively correlated with TnT (r value was 0.481, 0.367, 0.292, respectively, all P < 0.01), sICAM-1 (r value was 0.298, 0.249, 0.365, respectively, all P < 0.01), but negatively correlated with LVEF (r value was -0.384, -0.260, -0.200, respectively, all P < 0.01). In addition sICAM-1 positively correlated with TnT (r = 0.536, P = 0.000), but negatively correlated with LVEF (r = -0.341, P = 0.001).

Serum complements activation was found in the acute phase of ACS patients. Serum complement C3, C4 and C5b-9 are involved in the process of myocardial injury, and may reflect severity of myocardial injury and cardiac dysfunction.