O-38 TEG and thrombin generation during coronary artery bypass grafting: a comparison between on-pump and off-pump techniques

Abstract

Off-pump (OPCAB) is frequently used to perform coronary artery bypass grafting (CABG). The advantages and disadvantages of this technique in comparison with the standard procedures performed with cardiac arrest and cardiopulmonary bypass (CPB) are becoming clearer. Cardiopulmonary bypass has been shown to be associated with platelet dysfunction, amplification of the fibrinolysis process, increased thrombin generation and activation of the inflammatory system. The aim of this study was to evaluate the different impact of these two techniques on haemostasis, through the use of Thrombin Generation® (Haemoscope Corporation). Thirty patients were randomized to ”On-Pump” or ”Off-Pump” coronary artery bypass grafting. No differences in the number of grafts performed were evaluated in the two groups. Standard coagulation laboratory tests were collected for both groups. The thromboelastographic (TEG) analysis and thrombin generation® were performed at 6 time points: before sternotomy (T0-baseline), after heparin administration (T1), at admission to Intensive Care Unit (T3), 6 hr postoperatively (T4) and in the first postoperative day (POD) (T5). The TEG variables analysed were: R (Reaction time, sec), K parameter, α angle, MA (maximum amplitude), LY 30 (lysis at 30 minutes) and CI (Coagulation Index). The TEG Thrombin Generation® variables analysed were: MTG (maximum rate of thrombin generation), TMG (time to maximum rate of thrombin generation) and TTG (Total Thrombin Generation). The analysis of Thrombin Generation® at T1 showed a TMG value lower in the On-Pump group. At the same time, the values of MTG and TTG were higher in the On-Pump group patients. At T4 time TMG values were significantly lower in the Off-Pump group. On the contrary T4 MTG and TTG values were significantly higher in the Off-Pump group. The T5 results were the same as T4. The simple TEG sample analysis showed no statistically significant differences. Our study confirms that the coagulation cascade is strongly activated during cardiopulmonary bypass with an increased total amount of thrombin generated. The Thrombin Generation® analysis shows that OPCAB surgery protects the coagulation system of these patients during the procedure, generating a state of hypercoagulability through the sixth postoperative hour until the first POD. The hypercoagulability subsequent to the off-pump procedure seems to be connected to a higher speed of thrombin generation, an increased peak and an increased total amount of thrombin generation.