Chronic Limb-Threatening Ischemia (Critical Limb Ischemia): Why Leg Pain at Rest Is a Medical Emergency — and How Blood Flow Gets Restored
Updated: 3 days ago
Quick Answer
Chronic limb-threatening ischemia is an advanced stage of peripheral artery disease in which severe plaque buildup drastically cuts off blood flow to the leg or foot [1] [2]. Signs include leg pain at rest, wounds that will not heal and discolored skin [1]. It raises the risk of amputation, heart attack, stroke and death [1], and prompt revascularization can save your limb [1].
What the research says
Bypass surgery did better when a good leg vein was available. In the BEST-CLI randomized trial (1,830 patients with CLTI), among patients with a usable great saphenous vein, a major limb event or death occurred in 42.6% after surgery versus 57.4% after endovascular therapy over a median of 2.7 years (hazard ratio 0.68). In patients without a suitable vein, results were similar (42.8% versus 47.7%) (Farber et al., N Engl J Med, 2022) [5].
For blockages below the knee, starting with an endovascular procedure did better. In the BASIL-2 trial of 345 patients who needed treatment of arteries below the knee, major amputation or death occurred in 63% of the vein bypass group versus 53% of the endovascular-first group (adjusted hazard ratio 1.35), mainly because fewer people died in the endovascular group (Bradbury et al., Lancet, 2023) [6].
There is a newer option when arteries can't be opened. In the PROMISE II study of 105 patients with no surgical or endovascular options, transcatheter arterialization of the deep veins gave 66.1% amputation-free survival at 6 months, and the limb was saved in 76.0% (Shishehbor et al., N Engl J Med, 2023) [4].
What Is Chronic Limb-Threatening Ischemia?
Chronic limb-threatening ischemia (CLTI), formerly called critical limb ischemia, is severely blocked blood flow to your leg or foot [1]. It's an advanced stage of peripheral artery disease (PAD) — a condition where the arteries that carry blood to your limbs become narrowed or blocked [1] [2].
You may have intense pain even when you're resting and open wounds on your affected limb [1]. It can cause skin sores and tissue death in areas that don't receive enough blood flow [1].
About 1 or 2 out of every 10 people with PAD develop CLTI [1]. This serious condition increases your risk of heart complications, amputation, and death [1].
Seek medical care right away if you think you have CLTI. Prompt treatment can save your limb and your life [1].
What Are the Symptoms?
The most common symptom is foot or leg pain that occurs at rest [1] [6]. Often, this pain is worse when you elevate your leg or lie flat. It may wake you up at night [1]. You might find that hanging your leg off the edge of your bed or getting up and walking around a small amount relieves the pain [1].
Some people don't feel any pain but have other symptoms, like skin sores that won't heal, or skin that looks purple, green, or black due to tissue death (gangrene) [1] [6].
Healthcare providers call this condition "chronic" because symptoms are present for more than two weeks [1]. But you shouldn't wait to seek care. If you have any of these symptoms, seek medical attention immediately.
Symptom | What You Might Notice |
Rest pain (most common) | Leg or foot pain while resting; worse when elevating the leg or lying flat; may wake you at night |
Pain relief pattern | Hanging the leg off the bed or walking around a little may ease the pain |
Wounds that won't heal | Skin sores that persist on the affected leg or foot |
Signs of tissue death | Skin that looks purple, green, or black (gangrene) |
Some have no pain | A minority of people feel no pain but still develop sores and tissue death |
What Causes Chronic Limb-Threatening Ischemia?
Severe plaque buildup in your peripheral arteries (the arteries in any of your limbs, but typically your legs) causes CLTI. This process is called atherosclerosis [1]. As your arteries narrow, less blood can reach certain tissues in your leg or foot. It's harder for these tissues to remain healthy and strong, or to heal, without enough blood flow [1].
Plaque buildup is also responsible for the earlier stages of PAD, like leg cramps or achiness when you're walking or exercising [1]. But with CLTI, the plaque severely restricts blood flow. Very little blood can get where it needs to go — which is why CLTI symptoms are much more severe [1]. Body tissues can even begin to die, or won't heal when damaged.
Who Is at Higher Risk?
Anyone with PAD can develop chronic limb-threatening ischemia (CLTI), and managing peripheral artery disease early can lower the risk [1]. You have an increased risk if you:
Risk Factor | Why It Matters |
Age over 75 | Risk rises with age |
Continuing to smoke after a PAD diagnosis | Smoking worsens artery damage |
Diabetes | Affects blood vessels and healing |
Chronic kidney disease | Linked to more severe artery disease |
Atherosclerosis elsewhere | In other areas, such as coronary artery disease or cerebrovascular disease |
Depression | Associated with higher CLTI risk |
How to Lower Your Risk
You can lower your risk of CLTI by working with a healthcare provider to manage peripheral artery disease in its earlier stages. This may involve taking medications, doing structured exercise therapy (supervised by a healthcare provider), eating heart-healthy foods, quitting smoking, and following your provider's advice on foot care [1].
What Are the Complications?
Without treatment, CLTI can lead to limb loss (amputation) [1]. Having CLTI also raises your risk for a heart attack, stroke, or dying. That's because the same kind of plaque that builds up in your leg arteries can also build up in other arteries — including those that supply blood to your heart or brain [1].
Figure 2: Plaque in the leg arteries can lead to limb loss, heart attack, stroke, and death if CLTI is not treated.
How Is Chronic Limb-Threatening Ischemia Diagnosed?
Your healthcare provider will do a physical exam and talk with you about your symptoms. They'll check your pulse at several different points along both arms and legs [1]. If your provider thinks you may have CLTI, they'll run some noninvasive diagnostic tests:
Test | What It Measures |
Ankle-brachial index (ABI) | Compares blood pressure in your arms versus your ankles — shows if blood has a hard time reaching your feet |
Toe-brachial index | Like an ABI, but measures blood pressure at your toe instead of your ankle |
Pulse volume recordings | Part of the ABI test; measures volume changes caused by blood flow in your legs |
To help plan treatment, your provider may do imaging tests like a vascular ultrasound, CT angiogram, MRA (magnetic resonance angiography), or catheter angiogram [1].
Figure 3: Diagnosis combines pulse checks and blood pressure tests with imaging, and treatment focuses on restoring blood flow.
How Is Chronic Limb-Threatening Ischemia Treated?
To treat CLTI, your healthcare provider will do one or more procedures or surgeries to restore blood flow and heal skin wounds [1]. If there's severe tissue damage that isn't salvageable, you may need surgery to remove toes or even some or all of a limb [1]. In addition to treatment for the affected limb, you'll likely also need medicines and habit changes to lower your risk of future complications [1].
Procedures and Surgeries
Treatment | What It Does |
Leg revascularization | A procedure or surgery to help blood flow better in your leg — the gold standard for managing CLTI. Not an option in some cases, such as when there's gangrene or irreversible tissue damage |
Venous arterialization | An option if your arteries can't be opened: a provider connects an artery to a vein so oxygen-rich blood can reach your foot that way |
Wound care and infection control | Removing dead tissue (debridement) to prevent further damage and help nearby areas heal, plus specific wound care; antibiotics if you have a bacterial skin infection |
Amputation | Removing a portion of your toes or limb — a last resort that can even save your life in certain situations. With advances in prosthetics and physical therapy, most people can return to a fully functional life |
According to PubMed, about 20% of people with CLTI have no revascularization options, which can lead to above-ankle amputation [4]. In the PROMISE II study of 105 such patients, a catheter-based form of venous arterialization (transcatheter arterialization of the deep veins) achieved 66.1% amputation-free survival at 6 months and limb salvage in 76.0% (Kaplan-Meier) [4] (Shishehbor et al., N Engl J Med 2023; DOI: 10.1056/NEJMoa2212754). The 2024 ACC/AHA multi-society guideline covers CLTI as one of the main presentations of lower-extremity PAD [3] (Gornik et al., Circulation 2024; DOI: 10.1161/CIR.0000000000001251).
Medications and Habit Changes
Your provider may prescribe medicines to help keep the arteries open and lower your risk of a heart attack or stroke [1]:
Medicine | Purpose |
Antiplatelet drugs and anticoagulants | Lower your risk of blood clots |
High-dose statins | Reduce LDL ("bad") cholesterol and limit new atherosclerosis buildup |
Antihypertensives | Lower your blood pressure |
Diabetes treatment | Medication or other treatments to manage diabetes |
If you smoke, your provider will give you guidance on how to quit and suggest programs or medication to help [1].
Your provider will also talk with you about footwear and how to care for your feet. They may recommend using orthotics, like custom-made shoe inserts. These can help relieve pressure on certain parts of your foot, promoting wound healing and preventing new wounds from forming [1].
When Should I See My Healthcare Provider?
Contact a provider right away if you think you have CLTI. The sooner you get treatment, the better.
Treating CLTI takes time. You'll have many appointments and follow-up visits — often with different types of providers, like vascular surgeons, podiatrists, dietitians, and physical therapists [1]. These visits are all crucial for your healing. Be sure to tell your providers if it's hard for you to stick with your treatment plan or get to your appointments. They can offer resources to help [1].
What Is the Outlook?
Treatment for chronic limb-threatening ischemia can help save your limb and your life [1]. But each person is different, and many factors affect your outlook:
Whether it's possible to restore blood flow to your limb
How much tissue is damaged
Your age
Your other medical conditions [1]
Your healthcare provider can help you understand what's possible in your situation. It's important to know that chronic limb-threatening ischemia is a serious condition that can lead to limb loss or death. For example, up to 1 in 3 people with CLTI need a major amputation (above the ankle) within one year of diagnosis [1].
But there are also many reasons to have hope. Treatments continue to improve, and surgeons are finding more options all the time [1].
What is the bottom line on chronic limb-threatening ischemia?
Chronic limb-threatening ischemia — formerly called critical limb ischemia — is the most severe stage of peripheral artery disease, caused by heavy plaque buildup (atherosclerosis) in the leg arteries that cuts blood flow to a dangerously low level. Its signature symptom is leg or foot pain at rest (often worse lying flat and eased by dangling the leg or short walks), along with wounds that won't heal and skin discoloration signaling tissue death. About 1 or 2 out of every 10 people with PAD develop it, and it raises the risk of heart attack, stroke, amputation, and death. Diagnosis combines a pulse check, tests like the ankle-brachial index, and imaging such as CT angiogram or MRA. The gold-standard treatment is leg revascularization to restore blood flow, backed by wound care, medications (antiplatelets, statins, blood pressure and diabetes treatment), and lifestyle changes — with amputation as a last resort. Up to 1 in 3 people need a major amputation within a year of diagnosis, but treatment keeps improving. Because prompt care can save both limb and life, anyone with resting leg pain or non-healing foot wounds should see a healthcare provider immediately.
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Frequently Asked Questions
Q: What is chronic limb-threatening ischemia?
A: Chronic limb-threatening ischemia (CLTI), formerly called critical limb ischemia, is severely blocked blood flow to your leg or foot. It's an advanced stage of peripheral artery disease (PAD), caused by plaque buildup in the arteries.
Q: Is critical limb ischemia the same thing as chronic limb-threatening ischemia?
A: Yes. CLTI is the newer name for what was formerly called critical limb ischemia.
Q: How common is it?
A: About 1 or 2 out of every 10 people with PAD develop CLTI.
Q: What is the most common symptom?
A: Foot or leg pain that occurs at rest. The pain is often worse when you elevate your leg or lie flat, and it may wake you up at night.
Q: Why does dangling my leg relieve the pain?
A: Gravity helps a small amount of blood reach the foot when you hang your leg off the edge of your bed or get up and walk around a little — both can relieve the pain.
Q: Can you have CLTI without feeling pain?
A: Yes. Some people don't feel any pain but have other symptoms, like skin sores that won't heal and skin that looks purple, green, or black due to tissue death (gangrene).
Q: Why is it called "chronic"?
A: Healthcare providers call it "chronic" because symptoms are present for more than two weeks — but you still shouldn't wait to seek care.
Q: What causes chronic limb-threatening ischemia?
A: Severe plaque buildup in the peripheral arteries, typically in the legs. This process is called atherosclerosis, and as arteries narrow, less blood reaches the tissues in your leg or foot.
Q: Who is at highest risk?
A: Anyone with PAD can develop it. Risk is higher if you're over 75, keep smoking after your PAD diagnosis, have diabetes, have chronic kidney disease, have atherosclerosis elsewhere (coronary artery disease or cerebrovascular disease), or have depression.
Q: Can I lower my risk?
A: Yes — by working with a provider to manage PAD in its earlier stages: taking medications, doing supervised structured exercise therapy, eating heart-healthy foods, quitting smoking, and following foot care advice.
Q: What happens without treatment?
A: CLTI can lead to limb loss (amputation). It also raises your risk of heart attack, stroke, and dying, because the same plaque that builds up in leg arteries can build up in arteries supplying your heart or brain.
Q: How is it diagnosed?
A: Your provider does a physical exam and checks your pulse along both arms and legs, then runs noninvasive tests such as the ankle-brachial index (ABI), toe-brachial index, or pulse volume recordings. Imaging — vascular ultrasound, CT angiogram, MRA, or catheter angiogram — helps plan treatment.
Q: What is an ankle-brachial index (ABI)?
A: A test that compares blood pressure in your arms versus your ankles. It can show if blood has a hard time reaching your feet.
Q: How is it treated?
A: With one or more procedures or surgeries to restore blood flow and heal wounds — leg revascularization (the gold standard), venous arterialization, wound care and infection control, and amputation as a last resort — plus medications and habit changes.
Q: What is leg revascularization?
A: A procedure or surgery to help blood flow better in your leg. It's the gold standard for managing CLTI, but not an option when there's gangrene or irreversible tissue damage.
Q: What is venous arterialization?
A: An option when arteries can't be opened: a provider connects an artery to a vein so oxygen-rich blood can reach your foot through the vein instead.
Q: Will I lose my leg?
A: Not necessarily. Amputation — removing a portion of your toes or limb — is a last resort and can even save your life in certain situations. With advances in prosthetics and physical therapy, most people can return to a fully functional life.
Q: What medicines are typically prescribed?
A: Antiplatelet drugs and anticoagulants to lower blood clot risk, high-dose statins to reduce LDL cholesterol and limit new plaque, antihypertensives to lower blood pressure, and medication or other treatments to manage diabetes.
Q: What are orthotics, and how do they help?
A: Custom-made shoe inserts that relieve pressure on certain parts of your foot. This promotes wound healing and prevents new wounds from forming.
Q: How long does treatment take?
A: Treating CLTI takes time. You'll have many appointments and follow-up visits, often with vascular surgeons, podiatrists, dietitians, and physical therapists.
Q: What is the outlook?
A: Treatment can save your limb and your life, but it varies by person depending on whether blood flow can be restored, how much tissue is damaged, your age, and your other conditions. Up to 1 in 3 people with CLTI need a major amputation within one year of diagnosis — but treatments continue to improve, and surgeons are finding more options.
Related Reading
Learn more in our guide to Ankle-Brachial Index (ABI): Test, Normal Range and What Your Results Mean.
External Sources
Cleveland Clinic. Chronic Limb-Threatening Ischemia (Formerly Known as Critical Limb Ischemia). Cleveland Clinic. Last updated March 3, 2026. https://my.clevelandclinic.org/health/diseases/23120-critical-limb-ischemia
Daher G, Upadhyay S, Li J. Chronic Limb-Threatening Ischemia: A Comprehensive Review Paper. Interv Cardiol Clin. 2025;14(2):257-272. PMID 40049852. https://doi.org/10.1016/j.iccl.2024.11.011
Gornik HL, Aronow HD, Goodney PP, et al. 2024 ACC/AHA/AACVPR/APMA/ABC/SCAI/SVM/SVN/SVS/SIR/VESS Guideline for the Management of Lower Extremity Peripheral Artery Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2024;149(24):e1313-e1410. PMID 38743805. https://doi.org/10.1161/CIR.0000000000001251
Shishehbor MH, Powell RJ, Montero-Baker MF, et al. Transcatheter Arterialization of Deep Veins in Chronic Limb-Threatening Ischemia. N Engl J Med. 2023;388(13):1171-1180. PMID 36988592. https://doi.org/10.1056/NEJMoa2212754
Farber A, Menard MT, Conte MS, et al. Surgery or Endovascular Therapy for Chronic Limb-Threatening Ischemia. N Engl J Med. 2022;387(25):2305-2316. PMID 36342173. https://doi.org/10.1056/NEJMoa2207899
Bradbury AW, Moakes CA, Popplewell M, et al. A vein bypass first versus a best endovascular treatment first revascularisation strategy for patients with chronic limb threatening ischaemia who required an infra-popliteal, with or without an additional more proximal infra-inguinal revascularisation procedure to restore limb perfusion (BASIL-2): an open-label, randomised, multicentre, phase 3 trial. Lancet. 2023;401(10390):1798-1809. PMID 37116524. https://doi.org/10.1016/S0140-6736(23)00462-2
Medical Disclaimer
This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the guidance of a physician or other qualified health provider with any questions you may have about a medical condition. Never disregard professional medical advice or delay seeking it because of something you read here. If you have leg or foot pain at rest, wounds that won't heal, or skin discoloration, seek medical care right away — prompt treatment can save your limb and your life.
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