CLTI Decision Frameworks and Limb-Preservation Strategy

39.1What chronic limb-threatening ischaemia decisions actually look like

The practical CLTI consultation should be structured around three questions. First, what is the patient’s operative and survival risk? Second, how severe is the limb threat, including wound burden, ischemia, and infection? Third, what arterial pathway can plausibly deliver durable inline flow to the threatened tissue? The Global Vascular Guidelines describe this as the PLAN framework: Patient risk, Limb severity by WIfI, and ANatomic complexity by GLASS. CLTI 2019 · GVG 2019 Used properly, PLAN prevents the common error of selecting a technique before defining the patient, the limb, and the target-artery pathway.

Prompt specialist assessment is central because delay is itself a limb-risk amplifier. Current US and European guidance supports urgent multidisciplinary CLTI evaluation, prompt referral to vascular expertise, objective testing, limb staging, and expedited revascularization when feasible. PAD 2024 Major amputation is not framed as a default failure pathway; it is reserved for patients without reasonable revascularization options or for those whose baseline functional limitation, comorbidity, or goals of care make limb salvage inappropriate. Editor's Choice European 2024

The patient’s cardiovascular risk belongs inside the limb-preservation decision, not after it. CLTI patients are threatened by limb loss and by near-term cardiovascular events, and registry-derived risk modeling reinforces that one-year cardiovascular-event prediction should influence revascularization planning, perioperative discussion, and follow-up intensity. Prediction Year Major 2025 · VQI CLTI Survival · 2018 A technically attractive bypass or endovascular procedure may still be the wrong first move if the patient’s short-term physiologic risk overwhelms the likely limb benefit.

Frailty and function must be discussed explicitly. Limb preservation is valuable when it preserves mobility, independence, wound healing, or meaningful quality of life; it is less valuable when repeated procedures prolong non-ambulation or delay necessary palliation. Contemporary CLTI frailty data support incorporating frailty into treatment selection and goals-of-care discussion, especially when the choices are complex revascularization, primary amputation, or comfort-focused wound care. Frailty and CLTI treatment selection 2021

39.2WIfI and GLASS — how clinicians read the threatened limb and its anatomy

WIfI is the clinical language of the threatened foot. Society Vascular Surgery 2014 It grades Wound, Ischemia, and foot Infection from 0 to 3, then combines those domains into stages 1 through 4 to estimate amputation risk and likely revascularization benefit. The teaching point for trainees is simple: a small dry toe wound, a plantar wound with infection, and forefoot gangrene are not interchangeable “CLTI wounds,” even if all occur in patients with peripheral artery disease. WIfI forces the team to describe the limb rather than relying on vague labels.

The WIfI stage should be assigned early and updated when the limb changes. Early validation showed a graded relationship between WIfI stage and one-year major-amputation risk, with stage 1 carrying less than 5 percent risk and stage 4 more than 30 percent risk; the classification discriminated outcomes in both diabetic and non-diabetic patients. WIfI Prognostic SR · 2019 · WIfI Validation · 2019 · WIfI early validation 2014 This does not make WIfI a perfect outcome predictor, but it makes it a practical common scale for triage, counseling, and prioritizing revascularization.

GLASS is the anatomic counterpart to WIfI. CLTI 2019 · GLASS Methodology · 2021 It grades femoral-popliteal and infra-popliteal disease segments from 0 to 4, integrates them into overall stages I through III, and links staging to a selected target-artery pathway for endovascular planning. At the table, GLASS asks the operator to name the route by which blood will reach the foot, not merely to report that the angiogram is “diffuse,” “tibial,” or “multilevel.”

GLASS should not be misused as a stand-alone prediction of success. CLTI 2019 It estimates anatomic feasibility and expected limb-based patency thresholds, but the treatment choice still depends on patient risk and limb severity. A high-complexity GLASS anatomy in a robust patient with severe tissue loss and good vein may point toward bypass; the same anatomy in a frail patient with limited baseline function may point toward endovascular palliation, primary amputation, or a narrower wound-control goal. GVG 2019 · Frailty and CLTI treatment selection 2021

WIfI and GLASS are most useful when they are used together. CLTI 2019 · Society Vascular Surgery 2014 WIfI tells the team how much limb is at risk and how urgently healing must be achieved; GLASS tells the team how difficult it will be to deliver and maintain perfusion through a chosen arterial path. The combined reading prevents two recurrent mistakes: performing a low-durability procedure for a high-threat limb that needs lasting perfusion, and exposing a low-threat limb or high-risk patient to an operation whose burden exceeds the expected benefit.

39.3BEST-CLI and BASIL-2 — what the randomised evidence actually says

BASIL-1 remains useful historical context because it randomized 452 patients with severe lower-limb ischemia from infrainguinal disease to bypass-first or angioplasty-first treatment. BASIL-1 2005 Amputation-free survival and overall survival were similar during the first 2 years; beyond 2 years, bypass-first showed a survival advantage among those who survived to that timepoint. The lesson is not that old angioplasty and modern endovascular therapy are equivalent, but that life expectancy has always been central to choosing the initial strategy.

BEST-CLI is the major contemporary randomized reference point for patients suitable for either open bypass or endovascular therapy. BEST-CLI 2022 In cohort 1, which included patients with adequate single-segment great saphenous vein, open vein bypass reduced the composite of major adverse limb event or death compared with endovascular therapy at a median 2.7 years: 42.6 percent versus 57.4 percent, hazard ratio 0.68. The benefit was driven by lower major reintervention and above-ankle amputation, making the availability of good vein a decisive clinical variable rather than a technical afterthought.

BEST-CLI cohort 2 is equally important because it shows what happens when suitable vein is absent. BEST-CLI 2022 In that cohort, the composite outcome was not significantly different between bypass and endovascular therapy, 42.8 percent versus 47.7 percent. A prosthetic or alternative-conduit bypass pathway therefore should not be assumed to reproduce the cohort 1 advantage; when the vein is poor or absent, the balance often shifts toward individualized selection rather than automatic open reconstruction.

BASIL-2 gives a different signal in a different population. BASIL-2 2023 It randomized 345 CLTI patients requiring infra-popliteal revascularization to vein-bypass-first or best-endovascular-treatment-first. The primary outcome of above-ankle amputation or death occurred in 63 percent with vein bypass first versus 53 percent with endovascular-first therapy, hazard ratio 1.35, driven by higher early mortality in the bypass-first arm. This trial warns against applying a broad bypass-first rule to all tibial CLTI patients, especially where early operative mortality and infra-popliteal disease burden dominate the decision.

The randomized trials are best read as boundary conditions, not slogans. BEST-CLI supports open vein bypass for appropriate-risk patients with usable single-segment great saphenous vein, while BASIL-2 supports caution in infra-popliteal CLTI populations where early mortality may erase limb benefit. BASIL-2 2023 · BEST-CLI 2022 The responsible trainee should therefore ask: Is there good vein? Is the target path suitable? Is the patient likely to live long enough and function well enough to benefit from durability? Is the limb threat high enough to justify the treatment burden? GVG 2019

39.4Reading the evidence into a CLTI pathway: who gets bypass, who gets endovascular, who needs more time

A practical CLTI pathway begins with triage. Confirm CLTI with symptoms or tissue loss plus objective arterial disease; stage the limb with WIfI; define arterial anatomy and a target-artery pathway with GLASS; and estimate patient risk, survival, frailty, and functional goals. Only after those steps should the team choose endovascular treatment, open bypass, hybrid revascularization, primary amputation, or palliation. This sequence is the central discipline of PLAN-based care. CLTI 2019 · GVG 2019

Bypass is most compelling when four conditions align: the limb threat is meaningful, anatomy is complex enough that durability matters, surgical risk is acceptable, and adequate single-segment great saphenous vein is available. That pattern matches the strongest BEST-CLI signal and the current European direction that open vein bypass is preferred when suitable vein exists and surgical risk is acceptable. BEST-CLI 2022 The operation is not chosen because bypass is “better”; it is chosen because the patient, limb, anatomy, and conduit create a setting in which bypass durability is likely to matter. Editor's Choice European 2024

Endovascular-first treatment is favored when surgical risk is high, when the patient’s physiologic reserve is limited, when anatomy is suitable for a target-artery pathway, or when the goal is to obtain enough perfusion for wound progress with lower upfront treatment burden. BASIL-2 supports caution with routine bypass-first treatment in infra-popliteal CLTI populations, and ESVS 2024 emphasizes endovascular-first selection for high-surgical-risk patients. Editor's Choice European 2024 · BASIL-2 2023 The endovascular plan should still be anatomically honest: the target path must plausibly support the wound’s healing requirement. CLTI 2019

Some patients need more time before definitive revascularization is selected, but “more time” must not mean drift. Time may be needed to clarify goals, assess frailty, review conduit, complete imaging, control foot infection through coordinated care, or determine whether major amputation offers a more realistic functional endpoint. The key is to keep the decision active, documented, and multidisciplinary, because US and European guidance both emphasize urgent CLTI evaluation and limb-saving revascularization when feasible. PAD 2024 · Editor's Choice European 2024 · Frailty and CLTI treatment selection 2021

Device choice should not substitute for strategy. Registry and device studies provide useful context: sirolimus-coated balloon experience in complex infrainguinal CLTI lesions showed technical success and wound-healing signals in a high-risk single-arm cohort, and updated randomized-trial meta-analysis through 5 years found no increased all-cause mortality or major-amputation signal for paclitaxel-coated devices. Safety paclitaxel-coated devices 2026 · Utility Sirolimus Eluting 2024 These data inform device safety and feasibility discussions, but they do not replace WIfI, GLASS, conduit assessment, or patient-risk selection. CLTI 2019

Follow-up should be planned as part of the initial strategy. Real-world VQI CLTI outcomes show 30-day mortality after lower-extremity revascularization of approximately 2–4 percent depending on procedure type, with one-year major amputation rates in the 8–14 percent range, varying by WIfI stage and comorbidity. VQI CLTI 2022 A Medicare-linked VQI comparison also found that bypass and peripheral vascular intervention outcomes remain vulnerable to confounding and competing risks over time. VQI 2023 These registry signals remind the surgeon that limb preservation is a longitudinal program, not a single successful angiogram or bypass.

39.5GVG 2019, AHA/ACC/SVS 2024, and ESVS 2024 — agreement and the open seams

The major contemporary frameworks agree on the fundamentals. CLTI should be defined by clinical limb threat plus objective vascular disease; the patient should reach vascular expertise promptly; limb severity should be staged; anatomy should be described in a way that supports revascularization planning; and revascularization should be expedited when it is feasible and aligned with the patient’s goals. This shared structure is more important for daily practice than memorizing differences in guideline wording. PAD 2024 · Editor's Choice European 2024 · CLTI 2019

GVG 2019 provides the clearest decision architecture through PLAN. It explicitly ties patient risk, WIfI limb severity, and GLASS anatomic complexity to the choice among endovascular treatment, open bypass, hybrid treatment, primary amputation, or palliation. Its strength is that it resists a single-modality answer: high limb threat does not automatically mean bypass, and complex anatomy does not automatically mean operation if patient risk or goals do not support it. CLTI 2019 · GVG 2019

The 2024 ACC/AHA multisociety PAD guideline reinforces the CLTI pathway for US practice. PAD 2024 It supports interdisciplinary care, prompt referral to a vascular specialist, objective testing, limb staging with WIfI/GLASS-equivalent tools, shared decision-making, and expedited limb-saving revascularization when feasible. It also keeps major amputation in its proper place: a considered option for patients without revascularization options or with severe baseline functional limitation, not a reflex response to tissue loss.

ESVS 2024 aligns closely but gives particularly explicit practical direction on modality selection. Editor's Choice European 2024 It emphasizes urgent multidisciplinary evaluation, WIfI staging at first contact, and revascularization choice based on patient risk, limb severity, and anatomic complexity. It favors endovascular-first treatment for high-surgical-risk patients and open vein bypass when adequate single-segment great saphenous vein is present and surgical risk is acceptable.

The open seams are where judgment remains necessary. BEST-CLI and BASIL-2 do not produce a universal rule because they studied different CLTI populations and different anatomic mixes; registries add real-world risk estimates but cannot remove selection bias; device studies inform feasibility and safety without settling the strategy question. BASIL-2 2023 · BEST-CLI 2022 The surgeon’s task is to synthesize these seams transparently: show the patient why the proposed path matches their limb stage, anatomy, conduit, risk, life expectancy, and functional goals. Utility Sirolimus Eluting 2024 · VQI CLTI 2022