Effectiveness of recombinant desulphatohirudin in reducing restenosis after balloon angioplasty of atherosclerotic femoral arteries in rabbits

Background. The effectiveness of balloon angioplasty is limited by a restenosis rate of approximately 30%. Recombinant desulphatohirudin (r-hirudin [CGP 39393]) has been found to be highly effective in preventing acute platelet-rich thrombosis after deep arterial injury as compared with heparin. Methods and Results. This study evaluated the effect of intravenous r-hirudin, a selective inhibitor of thrombin, on restenosis after balloon angioplasty in 29 rabbits. Focal femoral atherosclerosis was induced by air desiccation endothelial injury followed by a 2% cholesterol diet for 1 month. At angioplasty (2.5-mm balloon with three 60-second, 10-atm inflations 60 seconds apart), the rabbits received heparin (150 units/kg bolus, n=16) or r-hirudin (1 mg/kg bolus followed by infusions of 1 mg/kg for the first hour and 0.5 mg/kg for the second hour, n=13). Angiograms performed before and after angioplasty and before death were analyzed quantitatively by a blinded observer. Rabbits were killed 2 hours (n=14) or 28 days (n=15) after angioplasty. Femoral arteries were fixed in situ by perfusion of 10% formaldehyde at 100 mm Hg. The mean luminal diameter of the arteries with successful angioplasty (≥20% increase in luminal diameter) in rabbits treated with heparin (n=8 arteries) increased from 1.18±0.29 mm before angioplasty to 1.86±0.24 mm immediately after angioplasty (p<0.001) and decreased to 0.94±0.69 mm (p=0.0004) at 28 days after angioplasty. In rabbits treated with r-hirudin (n=11 arteries), the mean luminal diameter increased from 1.14±0.17 mm before angioplasty to 1.68±0.20 mm immediately after angioplasty (p<0.001) and decreased to 1.37±0.47 mm (p=0.01) at 28 days after angioplasty. The mean reduction in luminal diameter by angiography was less in the r-hirudin-treated group than in the heparin-treated group (0.30±0.33 versus 0.92±0.61 mm, p=0.01). Blinded planimetric analysis of stained histological sections of the femoral arteries also showed less cross-sectional area narrowing by plaque in rabbits treated with r-hirudin compared with those treated with heparin (22±16% versus 48±29%, p=0.01). Both groups had similar numbers of arteries with histological evidence of balloon-induced plaque tear (12 of 13 versus 13 of 15). Conclusions. Rabbits receiving r-hirudin at the time of experimental balloon angioplasty had significantly less restenosis by angiography and by quantitative histopathology than rabbits receiving heparin.