In the EVOLUTION OFF trial, we evaluated the safety and efficacy of bivalirudin during off-pump coronary artery bypass grafting as compared with heparin-protamine. In this subanalysis of EVOLUTION OFF data of bivalirudin-treated patients, we assessed the pharmacokinetics (PK) and effectiveness of bivalirudin anticoagulation to achieve target activated clotting time (ACT)+ values. Data from 101 patients were assessed. A bolus of 0.75 mg/kg of bivalirudin was followed by a continuous infusion of 1.75 mg x kg(-1) x h(-1) during the grafting procedure. An ACT+ value of >300 s was the target. In four patients, PK data for bivalirudin were obtained. Only in exceptional cases were repeat fractional boluses or an increase of the infusion rate required. Assessment of the PK data showed a mean concentration of bivalirudin after the initial bolus of 11.0 +/- 0.53 microg/mL and a mean concentration during infusion of 11.2 +/- 2.32 microg/mL. Pearson's correlation between bivalirudin concentrations and ACT+ values was 0.92. Bivalirudin PK data consistently exceeded concentrations of 6.5 microg/mL, which have been evaluated as effective during percutaneous coronary intervention. The correlation between bivalirudin levels and ACT+ values was good, and the target ACT+ values were almost always achieved. These results suggest that bivalirudin, given according to the current protocol, provides reliable and effective anticoagulation during off-pump coronary artery bypass graft surgery.