Heparin and restenosis following angioplasty: A study of the effect of subcutaneous heparin on angiographic recurrence following angioplasty.

Restenosis following percutaneous transluminal coronary angioplasty (PTCA) continues to be the major limitation of the procedure with an incidence of 30-50%. The restenotic process is characterised by myointimal hyperplasia, initiated by smooth muscle cell migration and proliferation. Work in animal models of vascular injury suggests that heparin may reduce myointimal hyperplasia and hence restenosis. I therefore evaluated the effects of unfractionated heparin, 12 500 IU, twice daily, for 4 months, on angiographic and clinical restenosis following PTCA. 339 patients were randomised to receive no heparin (n=172) or 12 500 IU of heparin twice daily (n=167), with angiographic follow-up at 4 months. Blinded quantitative angiographic analysis was undertaken to determine the minimal luminal diameter (mid) pre PTCA, post PTCA and at follow-up. 40 patients defaulted, and 39 patients underwent "early" cardiac catheterisation. A total of 260 patients underwent elective cardiac catheter (n=136 in the no heparin group, n=124 in the heparin group). The mean difference between the mld at follow-up and immediately post PTCA was -0.49 mm(0.57) in the no heparin group, and -0.41mm(0.57) in the heparin group. The treatment effect, 0.08mm, was not significant (p=0.22). The restenosis rate in the no heparin group was 48% and 39% in the heparin group (p=0.32). For early and elective patients combined, the mean difference in mld at follow-up and post PTCA was -0.55 mm(0.58) for the no heparin group, and -0.43 mm(0.59) for the heparin group. The overall treatment effect was 0.12mm, (p=0.06), restenosis rate, 51% in the no heparin group and 41% in the heparin group (p=0.09). At elective follow-up 33% of patients in the no heparin group and 32% of the patients in the heparin group complained of angina. Unfractionated heparin at a dose of 12 500IU twice daily for 4 months does not significantly reduce angiographic or clinical restenosis rates following PTCA.