Neointimal hyperplasia and thrombosis initiated by platelet activity may contribute to the failure of femoropopliteal Dacron bypass grafts. We have therefore undertaken a randomised prospective double blind trial comparing the efficacy of a combination of acetyl salicylic acid (ASA) 330 mg and dipyrida mole (DPM) 75 mg three times daily, with placebo in maintaining the patency of femoropopliteal Dacron bypass grafts implanted to relieve disabling claudica tion. Patients received either ASA/DPM or placebo commencing pre-opera tively and continuing for 12 months. Seventy-three double velour (Microvel) grafts in 65 patients were studied, 38 grafts in the placebo group and 35 grafts in the active group. The following were measured pre-operatively and at 3, 6, 9 and 12 months postoperatively: maximum walking distance (MWD); ankle/bra chial systolic pressure index (ABSPI); graft patency; platelet adhesion and ag gregation; template bleeding time; ASA and DPM levels. After 1 year, 10 patients had been withdrawn (9 ASA/DPM: 1 placebo) and 4 out of 26 grafts in the active group and 15 out of 37 in the placebo group had occluded ( P < 0.05 Chi square test).
We conclude that inhibition of platelet function by the use of a combination of ASA and DPM improved the patency rate of femoropopliteal Dacron bypass grafts.
