Impact of minimally invasive extracorporeal circulation on coagulation-a randomized trial

Abstract

Objectives: Minimally invasive extracorporeal circulation (MiECC) is suggested to have favourable impact on blood loss compared to conventional extracorporeal circulation. We aimed to compare the impact of both systems on coagulation.

Methods: Randomized trial comparing endogenous thrombin-generating potential early after elective coronary surgery employing either MiECC group (n = 30) or conventional extracorporeal circulation group (n = 30). Secondary outcomes were in vivo thrombin generation, bleeding end points and haemodilution, as well as morbidity and mortality up to 30-day follow-up.

Results: Compared to the conventional extracorporeal circulation group, the MiECC group showed (i) a trend towards a higher early postoperative endogenous thrombin-generating potential (P = 0.06), (ii) lower intraoperative levels of thrombin-antithrombin complex and prothrombin fragment 1 + 2 (P < 0.001), (iii) less haemodilution early postoperatively as measured by haematocrit and weight gain, but without correlation to coagulation factors or bleeding end points. Moreover, half as many patients required postoperative blood transfusion in the MiECC group (17% vs 37%, P = 0.14), although postoperative blood loss did not differ between groups (P = 0.84). Thrombin-antithrombin complex levels (rs = 0.36, P = 0.005) and prothrombin fragment 1 + 2 (rs = 0.45, P < 0.001), but not early postoperative endogenous thrombin-generating potential (rs = 0.05, P = 0.72), showed significant correlation to increased transfusion requirements. The MiECC group demonstrated significantly lower levels of creatine kinase-MB, lactate dehydrogenase and free haemoglobin indicating superior myocardial protection, less tissue damage and less haemolysis, respectively. Perioperative morbidity and 30-day mortality did not differ between groups.

Conclusions: Conventional but not MiECC is associated with significant intraoperative thrombin generation despite full heparinization. No correlation between coagulation factors or bleeding end points with the degree of haemodilution could be ascertained.

Clinicaltrials.gov identifier: NCT03216720.

Keywords: Blood transfusion; Coronary artery bypass grafting; Minimally invasive extracorporeal circulation; Thrombin generation.

© The Author(s) 2020. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Figures

Figure 1:

Study CONSORT flow diagram including inclusion and exclusion criteria. CABG: coronary artery bypass grafting; eGFR: estimated glomerular filtration rate.

Figure 2:

Flow chart of study interventions and blood sampling. Red drops symbolize time points of blood sampling. CABG: coronary artery bypass grafting; ECC: extracorporeal circulation; preop: preoperative.

Figure 3:

Perioperative levels of thrombin generation markers in both groups. Centre line indicates median; box, interquartile range; error bars, upper/lower adjacent values; and dots, outside values. ECC: extracorporeal circulation. Time points: on heparin: after weaning of ECC; post-protamine: after protaminization; 6 hours: 6 h after surgery; day 1: 1 postoperative day.

Figure 4:

Perioperative haematocrit levels in both groups. Centre line indicates median; box, interquartile range; error bars, upper/lower adjacent values; and dots, outside values. ECC: extracorporeal circulation; nadir intraoperative: lowest intraoperative value; 6 hours: 6 h after surgery; day 1: 1 postoperative day.