The efficacy of aspirin in patients undergoing infra-inguinal bypass and identification of high risk patients.

Aim: Infrainguinal bypass is an effective treatment for critical lower limb ischemia but up to 1/3 of these grafts will occlude within the 1st year. The aim of this audit was to evaluate the efficacy of aspirin in maintaining graft patency and also improving patient survival.
Methods: In a single audited year (1997) 125 bypasses were carried out. Seventy-nine were on aspirin, 34 on no treatment and 12 were on other agents and hence excluded from analysis. The indication for surgery was critical ischaemia in 101 and disabling claudication in 12. Autologous vein was used in 104 and prosthetic grafts in 9.
Results: The overall 2-year primary graft patency, secondary graft patency and limb salvage were 50%, 71% and 83%, respectively. The 2-year secondary patency in patients with or without aspirin was 73% and 64%, respectively (p<0.12-log rank test). The corresponding patient survival from vascular death in the 2 groups was 73% and 70% (p<0.67-log rank test). Crural/ pedal bypass (51/75 on aspirin) and smoking (51/61 on aspirin) were independent risk factors for graft failure and vascular death respectively whilst those with a previous myocardial infarct (21/28 on aspirin) reached significance in univariate analysis only (p< 0.03).
Conclusion: Aspirin was not a significant factor in preventing graft failure or vascular death in patients undergoing bypass for critical limb ischemia. Dual therapy with other antiplatelet agents needs to be considered in such patients particularly those undergoing crural/pedal bypass, smokers and those with a history of previous myocardial infarction.