Which is the best coagulation management in coronary surgery? Results of a randomised study on heparin concentration versus activated clotting time and three different surgical techniques

Objective: Heparin concentration surveillance (HEPCON) is an alternative to measurements of the activated clotting time (ACT) during cardiac operations. The benefit however is not unequivocally proven and the mechanisms not completely understood. A better preservation of coagulation factors is assumed, platelets could be spared by individualized dosing of protamine. The effects of the two measuring systems in different surgical strategies of coronary revascularisation are not yet investigated.

Methods: 60 patients were randomized for intraoperative measurement of heparin concentration (Hepcon HMS PLUS, Medtronic) or ACT. Furthermore, the patients were randomly assigned to conventional cardiopulmonary bypass (ONCAB), minimized bypass (MECC) or off-pump (OPCAB) resulting in six study groups. Clinical data (heparin and protamine dosages, blood loss, transfusions) and several markers of the coagulation system (platelets, factor II, factor V, factor VIII, factor X, D-dimer, thrombin-antithrombin III - complex, prothrombin fragment 1.2, antithrombin III and tissue factor pathway inhibitor) were assessed at seven time points.

Results: Heparin usage varied without significance (p = 0,87), but protamine was significantly lower dosed with the HEPCON regimen (p < 0,001) without difference between the surgical subgroups. Blood loss was slightly higher with the HEPCON regimen at 12 hours (p = 0,09) without significance inbetween the surgical subgroups (p = 0,86). Transfusions didn't differ significantly. The time course of the coagulation markers was very similar in the 6 study groups up to 72 hours postoperatively. The only significance was found for factor VIII comparing ONCAB and OPCAB (p = 0,02). None of the other coagulation markers showed significant differences, neither between the major groups of anticoagulation management (HEPCON vs ACT) or of the surgical approach (ONCAB vs MECC vs OPCAB) nor between the combined subgroups.

Conclusions: In this study of isolated coronary bypass operations, surgical technique and heparin management had no influence on coagulation parameters. Surprisingly, neither the avoidance or minimization of the extracorporeal circulation nor individualized heparin dosage showed the anticipated advantages in preservation of the coagulation system. The results, however, are possibly biased by the small size of the study groups and need further investigations.