SS16 - WIfI Staging and Long-term Outcomes After Infrainguinal Revascularization for Chronic Limb-threatening Ischemia

Objectives: The SVS Wound, Ischemia, foot Infection (WIfI) limb staging system was established to estimate risk of major amputation in chronic limb-threatening ischemia (CLTI) and to better stratify outcomes comparisons. There is little data on treatment outcomes beyond one year based on presenting WIfI stage.

Methods: This is a single-institution retrospective study of 308 patients who underwent infrainguinal revascularization for CLTI (2011-2020) with WIfI-stageable limbs. Patient characteristics and outcomes were gathered from the electronic medical record. Major amputation was defined as amputation transtibial or proximal. Data were analyzed based on presenting WIfI stage and initial treatment received at our center.

Results: Presenting WIfI stages were 1-2 (17%), 3 (29%) and 4 (54%). Index revascularization approach was bypass in 38% and endovascular in 62%. Operative mortality within 30 days was 3.2% and was not associated with WIfI stage or revascularization approach. Median follow-up time was 859 (IQR 259-1563) days. Major amputation or death occurred in 19% and 46% of patients at median times of 82 (IQR 28-231) days and 589 (IQR 196-1301) days, respectively. WIfI stage was independently associated with major amputation (p=0.006; Figure 1), as was revascularization approach (p=0.048, Figure 2). In a Cox proportional hazards model, factors independently associated with major amputation were revascularization via non-autogenous bypass [HR 3.3 (1.3-8.5), p=0.02] or endoluminal intervention [HR 2.2 (1.1-4.6), p=0.03], diabetes [HR 2.9 (1.2-6.8), p=0.02], WIfI stage 4 [HR 2.2 (1.2-3.8), p=0.009] and GLASS infrapopliteal disease grade [HR 1.3 (1.1-1.6), p=0.002]. In a Cox proportional hazards model for mortality, factors independently associated with mortality were heart failure [HR 2.1 (1.5-3.1), p< 0.001], end-stage renal disease [ESRD; HR 2.0 (1.3-3.0), p=0.002], WIfI stage 4 [HR 1.6 (1.1-2.2), p=0.01], and age [HR 1.0 (1.02-1.1), p< 0.001].
Among the 172 patients who presented with WIfI stage 4, Kaplan-Meier estimated rates of major amputation or death at 2 years were 29% ± 3.9% and 30% ± 3.7%, respectively. In a Cox proportional hazards model for major amputation in WIfI stage 4 including diabetes, ESRD, GLASS infrapopliteal disease grade and revascularization approach; the only factor independently associated with maintained limb salvage was revascularization via autogenous vein bypass [HR 0.37 (0.16-0.89), p=0.03].

Conclusions: WIfI stage at presentation is strongly associated with long-term risks of major amputation and death following infrainguinal revascularization for CLTI and should be used to stratify outcomes comparisons. Effective revascularization is critical in WIfI stage 4 disease, and autogenous vein bypass provides durable long-term limb preservation.