TRAPIDIL IN PREVENTING RESTENOSIS AFTER BALLOON ANGIOPLASTY IN THE ATHEROSCLEROTIC RABBIT

Trapidil (triazolopyrimidine) possesses activity against platelet-derived growth factor-induced cellular proliferation in vitro and intimal proliferation in vivo. The objective of this study was to determine if trapidil could prevent restenosis in experimentally induced atherosclerotic rabbits. New Zealand White rabbits with preexisting iliac arterial lesions induced by balloon deendothelialization underwent balloon angioplasty. Arteriography was performed before, immediately after, and 4 weeks after the balloon dilatation. Tissue sections of the dilated arterial segment were also analyzed morphometrically. Seventeen rabbits were randomized to two groups: a control group (n=8) and a trapidil-treated group (n=9). The treatment group received 30 mg/kg s.c. trapidil twice daily. The angiographic luminal diameters before and after dilatation were similar. At the 4-week restudy, there was a significant preservation of luminal diameter in the trapidil group compared with the control group (1.27±0.20 vs. 0.94±0.48 mm, respectively; p<0.005). When luminal diameters immediately after dilatation were compared with diameters at the 4-week restudy (i.e., when the degree of restenosis was assessed), there was a greater luminal diameter reduction in the control group than in the trapidil group (0.70±0.44 vs. 0.30±0.25 mm, respectively; p=0.005). By morphometric analyses, the luminal areas were also greater in the trapidil group than the control group (0.80±0.25 vs. 0.57±0.33 mm2, respectively; p=0.03). Intimal thickness was significantly less for the trapidil group than for the control group (0.33±0.15 vs. 0.44±0.15 mm, respectively; p=0.01), as well as medial thickness (0.09±0.03 vs. 0.11±0.03 mm, respectively; p=0.01). In this study, trapidil significantly increased the luminal area and reduced the intimal thickness in the atherosclerotic rabbit iliac artery after balloon angioplasty.