Activation of coagulation and fibrinolysis during coronary surgery - On-pump versus off-pump techniques

Background: The authors studied the changes in selected hemostatic variable s in patients undergoing coronary surgery with on-pump coronary artery bypa ss grafting (CABG) or off-pump coronary artery bypass surgery (OPCAB) techn iques. Methods: Platelet counts and plasma concentrations of antithrombin, fibrino gen, D dimer, alpha (2) antiplasmin, and plasminogen were measured preopera tively, 5 min after administration of heparin, 10 min after arrival in the intensive care unit, and 24 h after surgery in patients scheduled to underg o OPCAB (n = 15) or CABG (n = 15). To correct for dilution, hemostatic vari ables and platelet counts were adjusted for the changes in immunoglobulin G plasma concentrations and hematocrit, respectively. Results. Adjusting for dilution, antithrombin and fibrinogen concentrations decreased to a similar extent in patients undergoing OPCAB or CABG (pooled means and 95% confidence limits of the mean: 95.5% of baseline, 93-98%, P = 0.002, and 91.7% of baseline, 88-95%, P = 0.0001), respectively, whereas alpha (2)-antiplasmin concentrations were unchanged. Only CABG was associat ed with a reduction in platelet counts (76% of baseline, 66-85%, P = 0.0001 ), plasminogen concentrations (96% of baseline, 91-99%, P = 0.011), and inc reased D-dimer formation (476%, 309-741%, P = 0.004). Twenty-four hours aft er surgery, platelet counts were still lower in patients undergoing CABG (P = 0.049), but all the investigated variables adjusted for dilution were si milar in the two groups. Conclusions: Coronary surgery causes a net consumption of antithrombin and fibrinogen. A transient decrease in platelet counts, with plasminogen activ ation and increased D-dimer formation, however, is only observed with CABG. Twenty-four hours after surgery, the hemostatic profiles of patients in bo th groups are similar.