Recombinant hirudin as a periprocedural antithrombotic in coronary angioplasty for unstable angina pectoris

Percutaneous transluminal coronary angioplasty is often complicated by thrombotic abrupt vessel closure in patients with unstable angina pectoris. The present multicentre trial was performed to determine the feasibility of two-dose regimens of recombinant hirudin (r-hirudin) compared to standard heparin in patients undergoing coronary angioplasty for unstable angina, and to investigate the effects of the different treatment regimen on markers of coagulation activation. At five participating centres, 61 patients were randomly enrolled in one of two sequential groups of r-hirudin (group 1: 0.3 mg.kg-1 i.v. bolus, 0.12 mg.kg-1.h-1 i.v. infusion; 21 patients; group 2: 0.5 mg.kg-1 i.v. bolus, 0.24 mg.kg-1.h-1 i.v. infusion; 19 patients) or in a heparin control group (150 IU.kg-1 i.v. bolus, 20 IU.kg-1.h-1 i.v. infusion; 21 patients). Antithrombotic therapy was started immediately before coronary angioplasty and continued for 24 h. This was followed by a low-dose anticoagulant infusion for another 24 h (r-hirudin: 0.04 mg . kg-1 . h-1; heparin: 7 IU . kg-1 . h-1). Activated partial thromboplastin time, r-hirudin plasma concentrations by both immunological and functional assay, thrombin-hirudin complex, thrombin-antithrombin III complex, soluble fibrin, and prothrombin fragment 1 + 2 were closely monitored. The median partial thromboplastin time prolongations at 24 h vs baseline were found to be 1.9-fold and 2.3-fold in r-hirudin group 1 and dose group 2, respectively, and 3.0-fold in the heparin group. There was a dose-dependent correlation between partial thromboplastin time and the r-hirudin plasma levels (r = 0.61). In five of 21 patients of dose group 1, three of 19 patients of dose group 2, and 10/21 patients of the heparin group, partial thromboplastin time values exceeding the predefined target range prompted an interruption of the infusion. One major bleeding complication occurred in dose group 2. The functional assay for the estimation of r-hirudin plasma concentrations showed excellent correlations to the immunological technique (r = 0.99). Differences between the thrombin-hirudin complex levels could not be observed. Increased concentrations of thrombin-antithrombin III complex, soluble fibrin, and prothrombin fragment 1 + 2 were seen 4-8 h after coronary angioplasty and after reduction of the high-dose therapy in dose group 1 when compared with dose group 2 and the heparin group, respectively. Based on coagulation tests the present study showed the feasibility of a periprocedural antithrombotic regimen with r-hirudin for patients undergoing coronary angioplasty for unstable angina. In addition to the partial thromboplastin time the determination of r-hirudin plasma levels by a chromogenic substrate assay considerably improves the monitoring of therapy. The lower dose r-hirudin regimen seems to be suboptimal as periprocedural anticoagulation in coronary angioplasty patients as indicated by markers of thrombin generation and thrombin activity.