[Prognostic value of perioperative change of neutrophil elastase and myeloperoxidase in coronary circulation on perioperative myocardial injury and clinical outcome of patients underwent surgical valve replacement]

Objective: To investigate the clinical value of observing perioperative changes of myeloperoxidase (MPO) and neutrophil elastase (NE) in coronary artery circulation in patients underwent valve replacement surgery. Methods: This perspective cohort study was performed in patients who underwent valvular surgery in Nanjing Drum Tower Hospital and Fuwai Hospital from June 2021 to June 2022. Patients were divided into perioperative myocardial injury group and age-, sex- and type of cardiac procedure-matched non-perioperative myocardial injury control group in the ratio of 1∶1. Perioperative myocardial injury was defined as cardiac troponin T (cTnT)>0.8 μg/L on the first postoperative day (POD), and the cTnT level on the second POD increased by more than 10% compared with the cTnT level on the first POD. During the operation, blood samples were collected from the coronary sinus before clamping ascending aorta, and within 5 minutes after de-clamping ascending aorta. Then, the levels of MPO and NE on coronary sinus were continuously measured. The death, severe ventricular arrhythmia, pneumonia, re-intubation, repeat cardiac surgery, extracorporeal membrane oxygenation (ECMO), intra-aortic balloon pump (IABP), continuous renal replacement therapy (CRRT), mechanical ventilation time and the duration of intensive care unit (ICU) were recorded. The levels of MPO and NE and the incidence of clinical outcomes were compared between the myocardial injury group and the control group. The independent risk factors of myocardial injury were analyzed by multivariate logistic regression. Results: A total of 130 patients were enrolled, aged (60.6±7.6) years old, with 59 males (45.4%). There were 65 patients in the myocardial injury group and 65 patients in the control group. During hospitalization, there was no death, ECMO, IABP and CRRT cases in both groups. Compared with the control group, the incidence of severe ventricular arrhythmia (13.8%(9/65) vs. 3.1%(2/65), P=0.03), pneumonia (20.0%(13/65) vs. 3.1%(2/65), P=0.03), re-intubation (6.2%(4/65) vs. 0, P=0.04) was significantly higher in myocardial injury group. The mechanical ventilation time (16.8(10.7, 101.7) h vs. 7.5(4.7, 15.1) h, P<0.01), and the duration of ICU (3.7(2.7, 18.9) vs. 2.7(1.8, 6.9)d, P<0.01) were significantly longer in myocardial injury group compared with the control group. There was no significant difference in the levels of MPO and NE in coronary sinus blood between the two groups before aortic clamping (all P>0.05). However, MPO ((551.3±124.2) μg/L vs. (447.2±135.9) μg/L, P<0.01) and NE ((417.0±83.1)μg/L vs. (341.0±68.3)μg/L, P<0.01) after 5 min aortic de-clamping were significantly higher in myocardial injury group than in the control group. Multivariate logistic regression analysis showed that the levels of NE (OR=1.02, 95%CI: 1.01-1.02, P<0.01), MPO (OR=1.00, 95%CI: 1.00-1.01, P=0.02) and mechanical ventilation time (OR=1.03, 95%CI: 1.01-1.06, P=0.02) were independent risk factors of myocardial injury in patients after surgical valvular replacement. Conclusion: Perioperative myocardial injury is related poor clinical outcomes, perioperative NE and MPO in coronary artery circulation are independent risk factors of perioperative myocardial injury in patients undergoing valve replacement surgery.