Circulating endothelial cells – a super-sensitive marker of myocardial injury indicating superior myocardial protection for intermittent cold versus warm blood cardioplegia in patients undergoing CABG surgery

Objectives: To investigate the impact of intermittent cold (ICC) and intermittent warm blood cardioplegia (IWC) on clinical outcomes, markers of myocardial and endothelial injury in patients referred to elective on-pump coronary artery bypass graft (CABG) surgery.

Methods: Patients undergoing CABG procedures were randomized to ICC (n=32) or IWC (n=36). Myocardial injury was assessed by CK-MB and cardiac troponin T (cTnT), endothelial damage was quantified by concentrations of circulating endothelial cells (CECs), von Willebrand Factor (vWf) and soluble thrombomodulin (sTm) at baseline and at 1h, 6h, 12h and 24h postoperatively. Perioperative myocardial injury (PMI) and major adverse cardiac events (MACE: cardiac cause of death, PMI, postoperative inotropic support, need for IABP or ECMO) were recorded.

Results: Demographic data and preoperative risk profile of included patients were comoparable. Postoperative course of all patients was uneventfull regarding death, PMI and MACE. Levels of CK-MB and TnT did not show inter-group differences, however, concentrations of CECs peaked at 6h postoperatively and were significantly higher for IWC-patients compared to ICC-group at 1h (ICC: 10.1±3.9/mL; IWC: 18.4±4.1/mL; p=0.012) and 6h (ICC: 19.3±6.2/mL; IWC: 29.2±6.7/mL; p<0.001). Similarly, concentrations of vWf (ICC: 178.4±73.2 U/dL; IWC: 258.2±89.7 U/dL; p<0.001) and sTm (ICC: 3.2±2.1ng/mL; IWC: 5.2±2.4ng/mL; p=0.011) were significantly elevated in IWC-group at 1h postoperatively.

Conclusions: Concentration of CECs in patients undergoing CABG can serve as a super-sensitive marker for endothelial injury and implicates favourable myocardial protection properties of ICC compared to IWC, even though differences were not detectable in clinical endpoints.