DiagnosticsPublished: August 2026·Updated: August 2026·8 min read

Ankle-Brachial Index: The Heart Risk Test You Missed

The ankle-brachial index compares the blood pressure at your ankle with the pressure in your arm, and that single ratio tells us more about your heart than most people expect. When the arteries in your legs narrow with plaque — peripheral artery disease — the same process is almost always under way in the coronary arteries feeding your heart. A cholesterol panel and a blood-sugar reading describe your risk factors; the ankle-brachial index measures the damage those risk factors have already done. In Singapore, where diabetes and smoking keep peripheral artery disease common, this quiet test often reclassifies a patient from ‘moderate’ to ‘high’ risk and changes what we do next. Here is how it works, and why one arm reading at home cannot replace it.

Dr. Peter Chang

Triple Board-Certified Cardiologist & Vascular Specialist

What the Ankle-Brachial Index Actually Tells You

The ankle-brachial index (ABI) is simply the higher of the two ankle systolic pressures divided by the higher arm systolic pressure. A healthy result sits between 1.00 and 1.40. A value of 0.90 or below means the leg arteries are narrowed by plaque — that is peripheral artery disease, whether or not your legs hurt. A value above 1.40 means the vessels are so stiff and calcified they will not compress, which carries its own risk.

What makes the number valuable is that it is objective, cheap and repeatable. It does not care how you feel on the day. In our Singapore practice we use it as a window onto the whole arterial tree: if plaque has reached the arteries furthest from the heart, it has almost certainly reached the ones that matter most.

One Arm, Four Limbs: Why the Ratio Beats a Home Reading

A home blood pressure monitor takes one measurement, on one arm, of one thing: the pressure your heart generates against your brachial artery. It is excellent for tracking hypertension. It tells you nothing about whether the artery behind your knee is half blocked.

The ankle-brachial index uses four pressures — both arms, both ankles — and reads the relationship between them. In a healthy adult, ankle pressure is slightly higher than arm pressure. When it drops below the arm pressure, blood is struggling to get past a blockage on the way down. A single brachial reading of 128/80 can look reassuring while an ABI of 0.78 on the same patient is quietly flashing red. One number describes the pump; the other describes the pipes. In Singapore we see patients every week whose home readings were perfect and whose ankle-brachial index was not.

How Blocked Leg Arteries Predict a Blocked Heart

Peripheral artery disease and coronary artery disease are the same disease in different postcodes. Both are driven by cholesterol-laden plaque, and the ankle is just an easier place to detect it than the heart.

The evidence here is unusually strong. The Ankle Brachial Index Collaboration, a meta-analysis of nearly 48,000 people published in JAMA in 2008, found that a low ankle-brachial index roughly doubled 10-year rates of total mortality, cardiovascular death and major coronary events — across every Framingham risk category. Adding the ABI to the Framingham score reclassified the risk level of about 19% of men and 36% of women. In the Multi-Ethnic Study of Atherosclerosis (MESA), both a low and a high ABI predicted cardiovascular events even after adjusting for standard risk factors and newer biomarkers, with hazard ratios near 1.8. For Singapore patients sitting in the intermediate-risk grey zone, that reclassification is often the deciding factor.

The Warning Signs Your Legs Send First

About half of people with peripheral artery disease have no classic symptoms, which is exactly why the ankle-brachial index earns its place. When symptoms do appear, they are easy to dismiss as ageing or arthritis.

The textbook sign is intermittent claudication: a cramping ache in the calf, thigh or buttock that comes on after a predictable walking distance and eases within minutes of stopping. In Singapore's flat, air-conditioned malls people can walk for years without triggering it. Watch for these instead:

Leg or foot pain at rest, often worse at night and relieved by hanging the foot out of bed
A foot ulcer or toe wound that will not heal after two weeks
One foot that is persistently cold, pale or dusky compared with the other
Hair loss over the shins, shiny skin, or slow-growing toenails
Erectile dysfunction, which can be the first sign of pelvic artery narrowing

Having the Ankle-Brachial Index Test Done in Singapore

The test takes about 15 minutes. You lie flat for five minutes first, then a technician wraps blood pressure cuffs on both arms and both ankles and uses a hand-held Doppler probe to hear the pulse as each cuff deflates. There are no needles and nothing to swallow.

In Singapore the ankle-brachial index is widely available — at vascular clinics, some GP practices with the equipment, and cardiology centres including ours at Paragon Medical Centre on Orchard Road. Expect to pay roughly SGD 80 to SGD 200 as a standalone test, often less when it is bundled into a cardiovascular screening package. If the resting ABI is normal but your history suggests claudication, we may add an exercise ABI on a treadmill, which unmasks milder disease. Diabetics with stiff, non-compressible arteries may need a toe-brachial index instead.

What We Do With an Abnormal Result

An ankle-brachial index of 0.90 or below changes the conversation. It means you have established atherosclerosis, so the goal shifts from screening to secondary prevention — treating you as someone who has already declared cardiovascular disease.

In practice that usually means:

High-intensity statin therapy aiming for an LDL cholesterol below 1.8 mmol/L, and often lower
A single antiplatelet agent, usually low-dose aspirin or clopidogrel; some patients benefit from adding low-dose rivaroxaban
Tight blood pressure and glucose control, with the home brachial monitor now doing the job it is good at
A supervised or structured walking programme, which is first-line treatment for claudication
Assessment of the coronary arteries — a calcium score or CT coronary angiogram — since the ABI has told us plaque is present

Walking, Statins and Stopping Smoking: Turning the Number Around

The ankle-brachial index is not fixed. While a calcified artery will not soften, the trajectory of the disease responds well to a few decisive changes — and the earlier you start, the more leg you keep.

Stopping smoking is the single most powerful step; it slows disease progression and roughly halves the risk of needing an amputation or bypass. Structured walking — 30 to 45 minutes most days, walking into the discomfort, resting, then repeating — measurably lengthens pain-free walking distance within three months. Add a Mediterranean-style diet, statin therapy and good diabetes control and most patients stabilise.

See a cardiologist or vascular specialist promptly if you have leg pain at rest, a wound below the ankle that is not healing, or sudden coldness and pallor in one leg, which is an emergency. In Singapore, do not wait on a polyclinic referral queue for those symptoms — go directly, and our clinic on Orchard Road can usually see such cases within a day or two.

Frequently Asked Questions

Common Questions About Ankle-Brachial Index

What is a normal ankle-brachial index?

A normal ankle-brachial index is between 1.00 and 1.40. Values from 0.91 to 0.99 are borderline and usually warrant a repeat or an exercise test. A reading of 0.90 or below confirms peripheral artery disease, and below 0.40 indicates severe disease with a real threat to the limb. Above 1.40 means the arteries are too stiff to compress, which is common in diabetes and also carries increased cardiovascular risk.

How is the ankle-brachial index measured?

You rest flat for about five minutes. A technician places blood pressure cuffs on both arms and both ankles and uses a small Doppler ultrasound probe to detect the pulse as each cuff deflates. The highest ankle pressure on each side is divided by the highest arm pressure. The whole process takes 10 to 15 minutes, needs no needles, and is painless apart from the usual cuff squeeze.

How much does an ankle-brachial index test cost in Singapore?

As a standalone test in Singapore, expect roughly SGD 80 to SGD 200, depending on the clinic and whether an exercise component is added. It is frequently included at no extra charge within a cardiovascular or vascular screening package. Medisave generally does not cover screening tests, but if the ABI is done to investigate symptoms it may be claimable as part of a diagnostic work-up.

Can peripheral artery disease be reversed?

The plaque itself rarely disappears, but the disease can be stopped in its tracks and symptoms often improve substantially. Stopping smoking, a structured walking programme, statins and blood sugar control can lengthen pain-free walking distance and lower the risk of heart attack and stroke. Think of it as controllable rather than curable — much like high blood pressure.

Is the ankle-brachial index better than a home blood pressure reading for heart risk?

They measure different things. A home brachial reading tracks hypertension, one risk factor. The ankle-brachial index detects arterial damage that has already occurred, which is why it predicts heart attacks and strokes independently of blood pressure, cholesterol and the Framingham score. You want both: the home monitor to manage pressure, the ABI to reveal hidden disease. One is not a substitute for the other.

Who should get an ankle-brachial index test in Singapore?

We recommend it for anyone over 65, for those over 50 with a history of smoking or diabetes, and for anyone with leg pain on walking, a non-healing foot wound, or known heart or carotid disease. If you have a strong family history of early cardiovascular disease and your risk score sits on the fence, the ABI can settle which side you are on.