A pilot, prospective evaluation of a direct thrombin inhibitor, bivalirudin (Angiomax), in patients undergoing lower extremity bypass

Objective

Replacing heparin with bivalirudin has been beneficial in patients undergoing coronary intervention and coronary artery bypass. The use of this alternative anticoagulant during peripheral bypass operations has not been studied. Concerns over distal thrombosis using this direct thrombin inhibitor (DTI) prompted a single-arm, open-label, pilot prospective trial of bivalirudin in patients undergoing lower extremity bypass to assess perioperative safety and efficacy.

Methods

Between 2006 and 2007, 18 patients met criteria for enrollment and underwent primary lower extremity bypass using bivalirudin. All patients had severe symptomatic atherosclerotic disease requiring lower extremity bypass. Bivalirudin at a bolus dose of 0.75 mg/kg and continuous infusion of 1.75 mg/kg/hr was used as the sole anticoagulant.

Results

Patients (mean age, 67 years) underwent femoral-popliteal (n = 14) or femoral-tibial (n = 4) bypass preferentially using saphenous vein (83%). Mean operative time was 261 minutes, with bivalirudin infusion time of 95 ± 26 minutes (mean ± standard deviation). Reliable anticoagulation was achieved with weight-based dosing with activated clotting time values at baseline (systemic) of 131 ± 92 seconds, during infusion (systemic) of 347 ± 36 seconds, and from the distal vasculature (limb) of 345 ± 66 seconds. Distal limb bivalirudin levels were stable at 9755 ± 3860 ng/mL during clamp occlusion. Mean estimated blood loss was 332 ± 191 mL with four patients (22%) requiring blood products. One patient required revision of the proximal anastomosis during the initial hospitalization. At 30 days, all bypass operations were patent with improvement of mean ankle-brachial index from 0.57 to 0.81. There were no deaths, myocardial infarctions, or amputations in the 30-day postoperative period. Based on the Thrombolysis in Myocardial Infarction classification for bleeding, one patient had major bleeding (>2 units of packed red blood cells), and three patients had minor bleeding within the first 30 days.

Conclusions

Bivalirudin is a safe and effective anticoagulant for lower extremity bypass operations. Thrombosis beyond the distal clamp was not seen. A comparative trial to standard anticoagulation is warranted.