PROSTHETIC ABOVE-KNEE FEMOROPOPLITEAL BYPASS-GRAFTING - RESULTS OF A MULTICENTER RANDOMIZED PROSPECTIVE TRIAL

Purpose:There are excellent arguments in favor of the preferential use of prosthetic grafts above the knee for the treatment of infrainguina l occlusive disease. This approach has been popularized on the basis o f the seemingly acceptable results when using polytetrafluoroethylene (PTFE). However, in many centers, knitted Dacron polyester has been us ed in these patients, and there are several studies that show equivale nt and, in some, superior results with Dacron when compared with PTFE. The purpose of this study was to examine these results in a definitiv e way. Methods: A randomized prospective trial in eight clinical acade mic centers in the United States and Canada was initiated in 1991. Two hundred forty-four patients eligible for such a study, by virtue of c riteria extant in each institution at the time, were centrally randomi zed. They underwent placement of either a knitted Dacron polyester gra ft impregnated with collagen or a thin-wall expanded reenforced PTFE g raft to the above-knee popliteal artery, usually from the common femor al artery. They were frequently observed by protocol for as long as 5 years by a physical examination noninvasive hemodynamic study, includi ng duplex scanning in many instances. Continuing patency was noted, as were other potential adverse outcome events. The data were analyzed b y the log-rank test for cumulative patency and expressed as Kaplan-Mei er awes. Data were further analyzed with a Cox proportional hazards mo del. Results: There were no differences in graft groups in demographic or comorbid factors. The procedural mortality rate was zero, and the morbidity rate was low (6.5%). The long-term patient survival rate was excellent (77% at 3 years). At the end of these years, no statistical significance in primary or secondary patency rates was observed betwe en the two grafts (primary patency rate, 62%+/-14.4% for Dacron; 57%+/ -15.5% for PTFE). No unexpected adverse outcomes on limb status were n oted. Patency rates in both graft groups were inferior in patients who received small grafts (5 to 6 mm vs 7 to 8 mm; hazards ratio, 4.15) a nd younger (<65 years) smoking patients. Conclusions: The fact that th ese two prosthetic grafts performed in equivalent fashion in a control led, well-conducted prospective study is not surprising in spite of th e previous work that suggested differences. If the preferential use of synthetic bypass grafts above the knee is to be used, it should be re stricted to older nonsmokers with favorable anatomy. In that instance, the choice of graft material will depend on handling characteristics and cost. Above-knee prostheses should be only selectively used in you nger, smoking patients, and graft size should be carefully considered in patients who undergo this operation.