Masked Peripheral Arterial Disease: Definition, risk groups and detection

Obscured by symptoms of other conditions, masked peripheral arterial disease (PAD) poses a significant threat to individuals, particularly the elderly and those with specific comorbidities. Awareness of its dangers and the risk groups it affects is crucial for its detection and management. This blog sheds light on these issues and provides an insight into masked PAD detection.  For comprehensive information on masked PAD, its consequences and risk groups, please watch the following lecture [3] by Prof. Tristan Mirault from Paris Cité University (available in French).  

In this blog you will learn: 

• What is masked peripheral arterial disease?
• Who is at risk of masked peripheral arterial disease?
• How do we detect it?

What is masked peripheral arterial disease?

Peripheral arterial disease (PAD) is a condition characterised by a narrowing of the peripheral arteries, i.e. arteries that are not in the heart, but supply the blood from the heart to other areas of the body. PAD is often used synonymously with LEPAD (lower extremity peripheral arterial disease) as it most commonly affects the arteries of the lower limbs. [1]

PAD is difficult to detect as most patients do not experience any symptoms. A well-known symptom of PAD is intermittent claudication, “lower extremity skeletal muscle pain that occurs during exercise”, even walking. [2] It occurs because of the insufficient oxygen supply to the musculature, and stops when the patient rests.  

When an illness is masked, its symptoms are not easily recognisable or are attributed to other causes, which can lead to misdiagnosis or delayed diagnosis. Masked diseases often have subtle or atypical symptoms; they can be mistaken for those of other conditions or go unnoticed entirely.  

In the case of masked PAD, lower leg pain could be attributed to factors like old age, or may not appear at all because the patient with other comorbidities may not manage to walk long enough for intermittent claudication to develop. The pain may also not show because of the numbness of the feet – caused by a number of factors such as (e.g. diabetes-induced) peripheral neuropathy. In all these cases, the presence of a cardiovascular condition like PAD may remain hidden for a long time. However, timely detection is crucial as PAD can not only result in amputations, but is “strongly associated with mortality, primarily as a strong predictor of future myocardial infarction and stroke.” [1] 

Who is at risk of masked peripheral arterial disease?

When trying to detect PAD, one must consider the risk groups that are threatened by PAD and should undergo PAD screening.  

However, patients with comorbidities that can force them into a sedentary lifestyle should be considered as potentially threatened by masked PAD because they often do not exercise (walk) sufficiently for a symptom like claudication to appear. These comorbidities are often grave conditions that take centre stage in the patient’s life and treatment, so the medical check-ups often concentrate on their management (adherence to medication, injury prevention).  

Here are a few illustrative examples of patients that specialists and GPs may encounter in their daily practice: [3]

An elderly patient

The patient is aged and uses a walker. Her walking is mainly limited to going from the chair to the bed and back again. She no longer goes to the store or anywhere else on foot, so intermittent claudication symptoms will not appear.  

A patient with COPD, a smoker, on home oxygen therapy

The patient covers very short walking distances as he quickly becomes short of breath. He is then forced to sit down and rest. The distances are too short for exertion-caused claudication to appear. 

Hypertensive diabetic with peripheral neuropathy

She does not go out on foot because she may inadvertently become injured due to peripheral neuropathy. She is aware that injuries and cuts to her feet may not heal properly, which could even result in amputation. She therefore stays at home in comfortable footwear. Her sedentary lifestyle prevents the claudication from ever taking place. 

Patient with heart failure

His amount of walking and any other physical efforts are seriously limited by shortness of breath. Most medical consultations will concentrate on whether he is following his medication regimen.  

Patient with angina

The situation is similar to that of with the previous profile. Any physical efforts are strongly affected by dyspnea and chest pain. These symptoms will be at the centre of his medical examinations. 

How do we detect it?

The symptoms of intermittent claudication are similar to those of musculoskeletal pain, spinal stenosis and venous claudication. Intermittent claudication can appear in many forms – ranging from strong pain to cramps in different areas of the leg (depending on the location of the arterial narrowing). [2] All these symptoms call for a careful examination to determine the actual cause. 

In the case of masked PAD, claudication symptoms like: cold leg; numbness; leg pain at night in bed; hairless, shiny, blotchy foot skin with sores; and leg skin paleness (when elevated) and redness (when lowered) [4] could be indicative of the condition. 

2 simple leg examinations are recommended as a first step: [3]

Palpation of the pulses in the lower limbs

Pulse palpation is a part of the initial thorough clinical examination. It should be noted that it should be accompanied by a bilateral visual comparison of both lower extremities, determining the patient’s cardiovascular risk factors and noting additional factors that might be present.  

The absence of a pulse is a good indicator of PAD. However, the presence of a pulse does not rule out PAD. [3] For this reason, the combination of palpation of the pulses and the following examination is essential.

The Ankle-Brachial Index measurement

The 2017 ESC Guidelines [5] recommend early ABI measurement for: 

1. Patients with clinical suspicion (unnoticeable pulse; claudication or symptoms suggestive for LEAD; non-healing wound) 
2. Patients with clinical conditions (increasing risk): CAD; heart failure; abdominal aortic aneurism; CKD 
3. Asymptomatic individuals at risk: 

• under 50 years: family history for LEAD 
• under 65 years: cardiovascular risk factors (diabetes; hypertension; smoking; dyslipdaemia) 
• over 65 years: everyone. 

Automated Ankle-Brachial Index is a fast and effective way of measuring the ABI (please note that, in the UK, only manual Doppler ABI measurements may be used in patients with leg ulcers in accordance with the 2023 NICE Guidelines). As it only takes minutes, PAD risk group patients can be screened in a fast and effective manner, and can also be of great help as a first step when suspecting masked PAD. Depending on the patient’s other comorbidities, when incompressible arteries are present, the Toe-Brachial Index measurement can be used.  

Unveiling masked peripheral arterial disease involves an effort from both patients and healthcare providers. By being vigilant for subtle symptoms, adopting preventive measures, and seeking timely medical assistance, patients can mitigate the potentially grave consequences of this silent threat. To achieve that, the healthcare providers should emphasise the significance of early PAD detection in risk groups as this will significantly contribute to the treatment outcomes. 

Prof. Tristan Mirault, MD, PhD 

Prof. Tristan Mirault is a specialist of internal and vascular medicine. He works at the Paris Cité University as well as at the Hôpital Européen Georges Pompidou hospital in Paris (France). His research focuses on genetic and inflammatory vascular disorders as well as on biomechanical properties of the arterial wall.