ObjectiveTo investigate the influence of 6% hydroxyethyl starch (HES, 130/0.4)on blood coagulation of patients after off-pump coronary artery bypass grafting (opCAB)by thromboelastography (TEG). MethodsOne hundred patients undergoing elective opCAB in Department of Cardiovascular Surgery, General Hospital of Shenyang Military Area Command between May and July 2013 were enrolled in this study. All the patients were randomly divided into 2 groups using random number table method with 50 patients in each group. In the experimental group (G1 group), there were 27 males and 23 females with their age of 64.9±4.4 years, who received intravenous 6% HES (130/0.4)20 ml/kg in 4 hours postoperatively. In the control group (G2 group), there were 31 males and 19 females with their age of 63.1±5.8 years, who received intravenous lactated ringers 20 ml/kg in 4 hours postoperatively. After postoperative ICU admission, full blood count, coagulation tests and TEG were examined. Chest and mediastinal drainage was recorded at 6 hours and 24 hours postoperatively. ResultsThere was no statistical difference in chest and mediastinal drainage 24 hours postoperatively between the 2 groups (591.7±171.7 ml vs. 542.4±174.0 ml, P > 0.05). None of the patients received reexploration for bleeding. There was no statistical difference in hemoglobin, hematocrit, platelet count or traditional coagulation index between the 2 groups (P > 0.05). TEG showed no significant change in coagulation time after intravenous fluid infusion in either group. Reaction time was slightly extended in both groups, but there was no statistical difference in reaction time between the 2 groups (P > 0.05). Maximum amplitude (MA)of G1 group was significantly decreased after intravenous fluid infusion (55.9±10.0 mm vs. 62.8±7.9 mm, P < 0.05), but still within the normal range. There was no significant change in MA after intravenous fluid infusion in G2 group. ConclusionIntravenous infusion of 6% HES (130/0.4)20 ml/kg can reduce platelet function and clot strength, but does not significantly increase postoperative chest or mediastinal drainage, or the incidence of postoperative reexploration for bleeding. It's safe to administer 6% HES (130/0.4)for patients after OPCAB.