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Global Vascular Guideline on the Management of Chronic Limb Threatening Ischemia-a new foundation for evidence-based careMichael S. Conte MDProfessor and Chief, Division of Vascular and Endovascular Surgery

UCSF Vascular Symposium 2018: Global Vascular Guidelines on CLTI

Disclosures

• Co-editor, Global Vascular Guidelines Writing Group

• Abbott Vascular (advisory board)

• Symic, Inc. (advisory board)

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WFVS

The Global Vascular Guidelines (GVG) initiative is sponsored by an international

consortium of vascular societies, led by the European Society for Vascular Surgery

(ESVS), the Society for Vascular Surgery (SVS), and the World Federation of Vascular

Societies (WFVS)

Definitions: CLTI

The term critical limb ischemia (CLI) is outdated and fails to encompass the full spectrum of patients who are evaluated and treated for limb-threatening ischemia in modern practice

Instead, the term chronic limb-threatening ischemia (CLTI) is proposed, in order to include a broader and more heterogeneous group of patients with varying degrees of ischemia that can often delay wound healing and increase amputation risk.

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CLTI: criteria for diagnosis

WFVS

Ischemic rest pain typically described as pain in the mid- and forefoot at rest, often worse with recumbency and relieved by dependency, present for more than 2 weeks

Tissue Loss diabetic foot ulcer, non-healing lower limb or foot ulceration of at least 2 weeks duration, any gangrene

ABPI <0.4 (using higher of the DP / PT)

Absolute highest ankle pressure <50 mmHg

Absolute toe pressure <30 mmHg

TcP02 <20 Torr

Flat pulse volume recording waveforms

WIfI ischemia score ≥1

Objectively documented atherosclerotic PAD

CLTI: exclusions

• Absence of any significant PAD, eg, WIfI ischemia grade=0

• May be unique circumstances of impaired local perfusion (angiosome) not reflected by the WIfI ischemia grade for the limb as a whole

• Lower extremity wounds that are a direct result of acute trauma

• Ulcers of primarily venous origin

• Acute limb ischemia (onset ≤ 14 days)

• Impaired tissue perfusion related to non-atherosclerotic conditions

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Need for Structured Decision Making in CLTI

PLAN:

Patient Risk

Limb threat severity: WIfI Staging

Anatomic pattern of disease: GLASS system

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WFVS

Risk stratification tools

High Risk defined as expected perioperative mortality >5% OR expected 2 year survival <50%

Importance of Limb Staging in CLTI Broad spectrum of complexity and risk for limb loss Complicates analysis of outcomes and treatment decisions

Previous classification systems inadequately capture the full range of neuro-ischemic compromise

Fallacy of a specific hemodynamic threshold for “critical” ischemia SVS Wound, Ischemia, Foot Infection (WIfI) system Characterizes each of the three major components Grouped into 4 stages based on estimated risk for limb loss Multiple validation reports

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Definitions: WIfI• WIfI stratifies amputation risk according to the Wound, the degree of Ischemia, and 

presence and severity of foot Infection

• WIfI scores and clinical stages appear to strongly correlate with important clinical 

outcomes, including those included in SVS Objective Performance Goals (OPG): limb 

amputation, 1‐year amputation free survival, and wound healing time

• WIfI is currently being evaluated in

• Multi‐center trials in the US

• UK NIR HTA‐funded BASIL‐2 and BASIL‐3 trial 

• SVS VQI (Vascular Quality Initiative) Registry of lower extremity interventions.

WFVS

Wound Grade – Clinical Category

Grade Clinical Description

0 Ischemic rest pain; Pre‐gangrenous skin change, without frank ulcer or gangrene (Pedis or UT Class 0)

1 Minor tissue loss: small shallow ulceration) < 5 cm2 on foot or distal leg (Pedis or UT Class 1); no exposed bone unless limited to distal phalanx

2 Major tissue loss: deeper ulceration(s) with exposed bone, joint or tendon, ulcer 5‐10 cm2 not involving calcaneus – (Pedis or UT Classes 2 and 3); gangrenous changes limited to digits. Salvageable with multiple digital amps or standard TMA + skin coverage

3 Extensive ulcer/gangrene > 10 cm2 involving forefoot or midfoot; full thickness heel ulcer > 5 cm2 + calcaneal involvement. Salvageable only with complex foot reconstruction, nontraditional TMA (Chopart/Lisfranc); flap coverage or complex wound management needed

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Ischemia Grade – Noninvasive Assessment

Grade ABI Ankle SP TP

0 > 0.80 > 100 mm Hg > 60 mm Hg

1 0.60‐0.79 70‐99 mmHg 40‐59 mm Hg

2 0.40‐0.59 50‐69 mm Hg 30‐39 mm Hg

3 < 0.40 < 50 mm Hg < 30 mm Hg

ABI=ankle brachial index; SP= systolic pressure; TP=toe pressure

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Risk of Amputation

Benefit of Revascularization?

Note: These are NOT Concordant

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Study (year): # Limbs at Risk Stage 1 Stage 2 Stage 3 Stage 4

Cull (2014):151 37 (3%) 63 (10%) 43 (23%) 8 (40%)

Zhan (2015): 201 39 (0%) 50 (0%) 53 (8%) 59 (64%)*

Darling (2015): 551 5 (0%) 111 (10%) 222 (11%) 213 (24%)

Causey (2016): 160 21 (0%) 48 (8%) 42 (5%) 49 (20%)

Beropoulis (2016): 126 29 (0%) 42 (2%) 29 (3%) 26 (12%)

Ward (2016): 98 5 (0%) 21 (14%) 14 (21%) 58 (34%)

Darling (2017): 992 12 (0%) 293 (4%) 249 (4%) 438 (21%)

Robinson (2017): 262 48 (4%) 67  (16%) 64 (10%) 83 (22%)

Mathioudakis (2017): 279 95 (6.5%) 33 (6%) 87 (8%)**  64 (6%)***

N = 2820 (weighted mean) 291 (3.2%) 728 (6.8%) 803 (8.5%) 998 (24%)

Median (% 1 year amputation) 0% 8% 8% 22%

Risk of amputation versus WIfI Stage: Compilation of published data

Limb staging and appropriateness of revascularization

WFVS

• CLTI represents a range of limb severity and ischemia as described in WIfI staging.

• Severe ischemia (WIfI ischemia grade 3) mandates revascularization for limb salvage

• With increased stages of limb threat (WIfI stages 3, 4) moderate degrees of ischemia (grades 1, 2) may be appropriate to address

• Low risk limbs (WIfI Stage 1) should be treated with wound care; revascularization should be reserved for failure to heal (50% within 4‐6 weeks) or clinical signs of deterioration

• Not indicated for Ischemia grade 0

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Benefit of revascularization varies with severity of limb threat and ischemia

3

2

1

0

High benefit 

Low/Nil benefit

1 2 3 4Limb Severity (WIfI Stage)

Severity of Ischemia

(WIfIIschemia Grade) N/A

N/A

Rationale for a new anatomic staging system in CLTI

WFVS

• Schemes focused on individual lesions (e.g. TASC) or overall burden of disease (e.g. Bollinger) are not useful for defining evidence-based revascularization in CLTI

• Restoration of in-line flow to the foot is a primary technical goal of revascularization in CLTI, particularly in patients with tissue loss

• Factors that determine clinical success for endovascular and open bypass surgery are intrinsically different

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GLASS*: Assumptions and Approach

WFVS

• Focus on Infrainguinal Disease (SFA origin to foot)

• Clinician defines the primary Target Artery Path (TAP)

• Femoro-popliteal (FP) and Infra-popliteal (IP) segments separately graded (0-4), then combined into Three GLASS Stages for the limb (I-III)

• Infra-malleolar (pedal) disease graded; used as a modifier only

• Calcification graded as Severe or not; simplified system

• *Global Limb Anatomic Staging System

GLASS: Target Artery Path and Limb-Based Patency

WFVS

• Restoration of in‐line flow to the ankle and foot is a primary goal

• Target artery path (TAP): the selected continuous route of in‐line flow from groin to ankle

• TAP usually involves the least diseased IP artery; may be angiosome‐based

• Limb‐based patency (LBP): maintained patency of the TAP. Lost when:• Occlusion, critical stenosis, or re‐intervention affecting any portion of the TAP(anatomical failure), and/or: 

• Fall in ABI (≥ 0.15) or TBI (≥ 0.10), or ≥ 50% stenosis in the TAP, in the presence of recurrent or unresolved clinical symptoms (e.g. rest pain, worsening/persistent tissue loss; signifying hemodynamic failure)

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WFVS

WFVS

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WFVS

GLASS: Consensus Staging of TAP Complexity for Endovascular Intervention

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WFVS

Pedal disease modifier not included in overall limb stage assignment at present due to insufficient data on relationship to treatment outcomes

Examples of the GLASS system

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FP grading: Total length of SFA disease: 10‐20 cmPopliteal disease: <5cm does not involve trifurcationCalcification + 1FP grade = 4

IP grading: TAP= peroneal arteryPeroneal: stenosis TP trunkIP grade = 2 

GLASS Stage = III

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FP grading: SFA single stenosis/occlusion approx 5 cmPopliteal: no significant stenosisFP grade = 1

IP grading: TAP = ATAATA: 2 focal stenosis, <1/3 (<10cm)IP grade = 2

GLASS Stage = II

FP grading: SFA: no significant stenosisPopliteal: no significant stenosisFP grade = 0

IP grading: TAP = peroneal arteryPeroneal: CTO 3‐10cmIP grade = 3

GLASS Stage = II

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FP grading: SFA: no significant stenosisPopliteal: CTO extending into trifurcationFP grade = 4

IP grading: TAP = ATAATA: CTO target artery originIP grade = 3

GLASS Stage = III

Factors Determining Clinical Success Differ

High patient risk

More severe limb threat (e.g. WIfI Stage 4)

Greater target lesion/path complexity of occlusive disease

• Prior failed implant

Poor runoff

Good quality vein available

Good quality vein not available

FAVORS MORE

Bypass Endo

✔✔✔✔✔

✔✔✔✔✔--- ---

✔✔✔✔✔✔

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Preferred initial revascularization strategy for infra-inguinal disease, in average risk CLTI patients with adequate autogenous vein for bypass

Open Bypass 

Indeterminate

Endovascular

No Revascularization

1 2 3 4Limb Severity (WIfI Stage)

Anatomic Complexity

(GLA

SS Stage)

III

II

I

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• Funded by NHLBI in 2013

• Compare initial Endo vs initial Bypass in CLI

• Parallel trial, stratified design

• Target 2100 patients, approximately 120 centers

• Current enrollment approximately 900

Andrew W. BradburySampson Gamgee Professor of Vascular Surgery

University of Birmingham, UK

Heart of England NHS Foundation Trust, Birmingham, UK

BASIL 2 (BTK) – Bypass versus Angioplasty / Stenting in Severe Ischaemia of the Leg due to BTK Disease Trial

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