Comparison of desulfatohirudin (REVASC) and heparin as adjuncts to thrombolytic therapy with reteplase in a canine model of coronary thrombosis

1 We compared the direct thrombin inhibitor, desulfatohirudin (REVASC) and the indirect thrombin inhibitor, heparin, as adjuncts to thrombolytic therapy with reteplase in a canine model of coronary artery thrombosis. 2 Reteplase (BM 06.022) is a recombinant unglycosylated variant of human tissue-type plasminogen activator. Thrombus formation in anaesthetized open chest dogs was induced by electrical injury. Left circumflex coronary artery blood flow was monitored for 210 min with an electromagnetic flow probe. Twenty eight dogs were randomized to receive i.v. heparin (120 iu kg(-1) bolus plus 80 iu kg(-1) per h) or i.v. hirudin (2.0 mg kg(-1) bolus plus 2.0 mg kg(-1) per h) 10 min before thrombolysis preceded by i.v. acetylsalicyclic acid (20 mg kg(-1)) 5 min prior to anticoagulation. Every dog received an i.v. double bolus injection of 0.14 + 0.14 u kg(-1) (= 0.24 + 0.24 mg kg(-1)) reteplase, 30 min apart, 1 h after thrombus formation. 3 At comparable reperfusion rates (12 out of 12 vs. 15 out of 16 dogs), hirudin enhanced time to reperfusion (14.3 +/- 1.4 vs. 23.2 +/- 3.4 min; P < 0.05) and completely prevented reocclusion after reperfusion in contrast to heparin (0 out of 11 vs. 7 out of 11 dogs; P < 0.05). Coronary blood flow quality was improved by hirudin as shown by a higher maximum blood flow after reperfusion (130 +/- 14.3 vs. 83 +/- 9.3% of baseline; P < 0.05), a higher blood flow level at 20, 30, 40, and 50 min after onset of thrombolysis (P < 0.05) and a longer cumulative patency time (195 +/- 1.7 vs. 166 +/- 12 min; P < 0.05). Activated partial thromboplastin time and buccal mucosa bleeding time were prolonged (P < 0.05) by either anticoagulant, but did not differ significantly between groups. 4 The direct thrombin inhibitor, desulfatohirudin, enhanced thrombolysis, prevented reocclusion and increased blood flow as compared with the indirect thrombin inhibitor, heparin, when investigated at one dose level each and used in conjunction with reteplase.