Peripheral Arterial Disease: Why the Ankle-Brachial Index Remains a Key Tool for Cardiovascular Screening
A common, underdiagnosed disease associated with high cardiovascular risk
Cardiovascular disease remains the leading cause of death worldwide, accounting for nearly 18 million deaths each year (1). Among these conditions, peripheral arterial disease (PAD) affects more than 230 million people globally (2).
Yet this condition remains largely underdiagnosed. It is estimated that a significant proportion of affected patients are asymptomatic or present with nonspecific symptoms, delaying diagnosis and management (3).
This issue is particularly significant in certain at-risk populations, notably women. Cardiovascular disease is now the leading cause of death among women in France, ahead of all cancers combined (4).
According to Dr. Arthur Thery, vascular physician:
"We often say that women have atypical signs. In reality, they mainly have signs that differ from those we've been trained to recognize."
This difference in clinical presentation contributes to a diagnostic delay that remains common in women, both for coronary artery disease and for peripheral arterial disease.
PAD: a local manifestation of a systemic disease
PAD results from a progressive atherosclerotic process leading to thickening of the arterial wall and narrowing of blood vessels (5).
However, it is essential to view this condition as a systemic disease rather than a localized condition of the lower limbs.
As Dr. Thery explains:
"It's a systemic disease. Theoretically, all arteries can be affected by this mechanism."
Atherosclerosis can thus affect several vascular territories:
the carotid arteries, with a risk of stroke or transient ischemic attack (TIA);
the coronary arteries, potentially leading to myocardial infarction;
the arteries of the lower limbs;
the abdominal aorta, with the risk of abdominal aortic aneurysm (5,6).
This systemic dimension explains why the presence of PAD should be considered a major marker of overall cardiovascular risk (6).
A silent disease requiring active screening
Atherosclerosis is often called a "silent killer" due to its slow, asymptomatic progression over many years.
Clinical manifestations generally appear only when arterial lesions are already advanced, exposing patients to potentially serious complications (5,6).
This silent progression justifies the importance of early screening in patients with cardiovascular risk factors such as:
smoking;
high blood pressure;
diabetes;
dyslipidemia;
advanced age;
history of cardiovascular events (6,7).
ABI: a simple test that can change a patient's care pathway
Contrary to certain misconceptions, the initial diagnosis of PAD does not necessarily rely on complex imaging studies.
The Ankle-Brachial Index (ABI) is the first-line test recommended by international scientific societies (6,7).
This test is based on comparing blood pressure measured at the ankle with that measured at the arm.
An ABI below 0.90 is considered diagnostic of PAD (6,7).
According to Dr. Arthur Thery:
"If you just do that, and you have an ABI below 0.9, you've won. You've diagnosed peripheral arterial disease."
Beyond diagnosing PAD, ABI makes it possible to identify a patient at very high cardiovascular risk and to initiate a comprehensive secondary prevention approach.
The discovery of a pathological ABI should therefore lead to screening for other atherosclerotic conditions, optimizing risk factor control, and strengthening cardiovascular follow-up (6).
Don't stop at ABI: consider abdominal aortic aneurysm
While ABI is an excellent screening tool, it does not identify all manifestations of atherosclerosis.
Dr. Thery emphasizes the importance of not neglecting screening for abdominal aortic aneurysm in certain at-risk patients.
European guidelines recommend targeted ultrasound screening in older men with cardiovascular risk factors, particularly current or former smokers (8).
Abdominal aortic aneurysm remains asymptomatic in most cases until rupture, a complication associated with extremely high mortality (8).
What to do when ABI is above 1.4?
Interpreting ABI also requires understanding its limitations.
An ABI above 1.40 generally indicates arterial incompressibility related to medial arterial calcification, a situation frequently observed in diabetic, renal failure, or very elderly patients (6,9).
In these situations, toe pressure is a particularly useful diagnostic complement.
Since digital arteries are generally less affected by medial calcification, toe pressure measurement allows for a more reliable assessment of distal hemodynamic status (9).
This measurement is especially valuable in patients with wounds, trophic disorders, or suspected critical limb ischemia.
Toward an integrated approach to cardiovascular screening
For Dr. Thery, PAD should not be considered an isolated condition but rather a gateway to broader cardiovascular assessment.
When PAD is diagnosed, the first step is to look for potential involvement in other vascular territories.
"When I diagnose PAD, the first thing I do is offer the patient screening for other potential conditions."
Combining several complementary tests, particularly ECG and ABI, provides a more complete picture of a patient's cardiovascular risk and improves care pathway coordination.
Conclusion
Peripheral arterial disease remains a common condition, underdiagnosed and strongly associated with cardiovascular morbidity and mortality.
Thanks to its simplicity, low cost, and prognostic value, the Ankle-Brachial Index remains one of the most effective tools for early identification of patients at high cardiovascular risk (6,7).
Used within a comprehensive prevention strategy, it not only screens for PAD but also enables earlier detection of atherosclerotic disease as a whole and its potential complications.
Key takeaways
PAD affects more than 230 million people worldwide (2).
It is a local manifestation of systemic atherosclerotic disease (5,6).
Women remain underdiagnosed due to clinical presentations that often differ from those historically described (4).
ABI is the recommended first-line test for PAD screening (6,7).
A pathological ABI identifies patients at very high cardiovascular risk (6).
Toe pressure is particularly useful in patients with medial calcification or an ABI above 1.4 (9).
FAQ – ABI and PAD screening
Why is PAD considered a systemic disease?
Because atherosclerosis can simultaneously affect several vascular territories, including the coronary arteries, carotid arteries, abdominal aorta, and lower limb arteries (5,6).
What ABI threshold is used to diagnose PAD?
An ABI below 0.90 is considered diagnostic of peripheral arterial disease (6,7).
Why measure toe pressure?
Toe pressure is particularly useful in patients with medial arterial calcification, when ABI becomes difficult to interpret (9), for example in diabetic and chronic kidney disease patients.
Why screen for abdominal aortic aneurysm in certain patients?
Because this condition is generally asymptomatic until rupture and shares the same risk factors as atherosclerosis (8).
Is ABI reserved for vascular specialists?
No. ABI can be useful in general practice, cardiology, diabetology, or any specialty managing patients at cardiovascular risk (6,7).
