Failure to Achieve Clinical Improvement Despite Graft Patency in Patients Undergoing Lower Extremity Bypass for Critical Limb Ischemia

OBJECTIVES: Studies of lower extremity bypass for critical limb ischemia (CLI) have traditionally emphasized outcomes including patency, limb salvage, and death. Because functional outcomes are equally important, our objectives were to describe the proportion of CLI patients who do not experience symptomatic improvement one year after bypass despite having patent grafts, and to identify preoperative factors associated with this outcome.
METHODS: The prospectively collected Vascular Study Group of Northern New England database was used to identify all cases of elective lower extremity bypass for CLI (2003-2008) for which long-term follow-up data were available. The primary composite study endpoint was clinical failure, defined as persistent or worsening ischemic symptoms (rest pain/tissue loss), or amputation, despite having a patent graft, at 1 year post-bypass. Variables identified on univariate screen (inclusion threshold, p < 0.20) were included in a multivariable logistic regression model to identify independent predictors.
RESULTS: Bypasses were performed for CLI in 1029 patients with available long-term follow-up data, of which 803 (78%) remained patent at 1 year. Of these 803 patients, 81 (10.1%) patients met criteria for the composite endpoint of clinical failure: 22 (2.8%) for major amputations and 59 (7.3%) for persistent rest pain or tissue loss. In multivariable analysis, significant predictors of clinical failure included dialysis dependence (OR 3.68, 95%CI 1.81-7.58, p=.0003) and preoperative inability to ambulate independently (OR 2.26, 95%CI 1.33-3.64, p=.0027). History of coronary artery bypass graft or percutaneous coronary intervention were protective (OR 0.52, 95%CI 0.29-0.92, p=.0258).
CONCLUSIONS: After lower extremity bypass for CLI, 10% of patients with a patent graft fail to achieve clinical improvement at one year. Preoperative identification of this specific patient subgroup remains challenging. In order to improve surgical decision-making and the overall care of CLI patients, further studies focusing on functional outcomes as well as traditional surgical endpoints are necessary.