Effect of remote ischaemic conditioning on coagulation function as measured by rotational thromboelastometry and whole blood impedance aggregometry in off-pump coronary artery bypass surgery: a randomised controlled trial

Abstract

Introduction Remote ischaemic conditioning (RIC) has been shown to prevent platelet activation during ablation for atrial fibrillation. In the recent Remote Ischaemic Preconditioning with Postconditioning Outcome trial, RIC was associated with more postoperative transfusion in the off-pump coronary artery bypass graft surgery (OPCAB) subgroup. Transient tourniquet application on the limb affects the coagulation system; however, it remains unknown whether RIC affects the coagulation system during OPCAB. Methods A total of 58 patients undergoing OPCAB were randomised to the RIC or control group. In the RIC group, four cycles of 5 min of ischaemia and 5 min of reperfusion were applied twice to the upper arm after the induction of anaesthesia (preconditioning), and after the completion of coronary anastomoses (postconditioning). Whole blood impedance aggregometry (Multiplate®) and rotational thromboelastometry (ROTEM®) were performed before the induction of anaesthesia, at the end of surgery, and at postoperative day 1. Results The decrease in whole-blood aggregation by adenosine diphosphate at the end of surgery was greater in the RIC group than in the control group, but this effect was not statistically significant (46.7 [21.4] vs. 45.8 [22.6] U, P=0.880). In ROTEM® analysis, the EXTEM area under the velocity curve was lower in the RIC group than in the control group at the end of surgery (3,567 [1,399–5,794] vs. 5,693 [4,718–6,179] mm*100, respectively; P=0.03). However, there was no difference in other Multiplate® or ROTEM® parameters. An increased tendency of perioperative bleeding was identified in the RIC group. Discussion Although some parameters indicated a tendency for hypocoagulation in the RIC group at the end of surgery, most effects were not statistically significant. RIC does not significantly affect perioperative platelet aggregability and coagulation in patients undergoing OPCAB.