Antiplatelet and anticoagulant therapy to prevent bypass graft thrombosis in patients with lower extremity arterial occlusive disease.
The incidence of graft failure for above knee femoropopliteal grafts is described by the European Consensus Document on Critical Limb Ischaemia. It occurs in approximately 15% of patients when vein is used for the grafting procedure and in 20% of patients when PTFA (polytetrafluoroethylene) or other prosthetic material is used. Femorodistal grafts have a much poorer outcome with 45% and 75% failure rates for vein and prosthetic grafts, respectively. Prevention of primary graft failure and thus the need for surgical reintervention is of major clinical and economic importance. Early failure, occurring within one month of operation, is usually due to technical error such as poor patient selection or operative technique. Approximately 10% of graft failures will fall into this time period. When grafts thrombose after two years, progression of native atherosclerosis either proximally or distally is the usual cause. This accounts for 2-3% of all graft failures each year. The most common time for grafts to fail is between one month and two years (80% of all failures) and this is the same period in which graft stenoses are now known to develop. There are few evidence-based recommendations for the use of pharmacological agents in maintaining graft patency following peripheral vascular surgery. This article reviews the evidence for or against the use of anticoagulant and antiplatelet therapy for the prevention of bypass graft thrombosis in patients with peripheral arterial occlusive disease.