Does a raised Ankle-Brachial Pressure Index (ABPI) require referral to a vascular specialist?

From the Guidelines

A raised Ankle-Brachial Pressure Index (ABPI) above 1.3 generally requires referral to a vascular specialist. This is because an elevated ABPI suggests arterial calcification and vessel hardening, which can mask underlying peripheral arterial disease (PAD) and indicates increased cardiovascular risk 1. The vascular specialist will typically perform additional diagnostic tests such as toe-brachial index (TBI), duplex ultrasound, or CT angiography to properly assess vascular health since standard ABPI measurements become unreliable when vessels are calcified 1.

According to the 2024 ACC/AHA/AACVPR/APMA/ABC/SCAI/SVM/SVN/SVS/SIR/VESS guideline, the ABI is a useful tool for diagnosing PAD, but it has limitations, particularly in patients with diabetes or chronic kidney disease, where non-compressible arteries can result in a falsely elevated ABI 1. The guideline recommends using the toe-brachial index (TBI) as an alternative diagnostic test in these patients.

The European Heart Journal also recommends that values >1.40 be considered as 'non-compressible arteries' and that the ABI be used in conjunction with other diagnostic tests to confirm the presence and severity of PAD 1.

In terms of management, early specialist evaluation is crucial to establish appropriate monitoring and treatment plans to address both the vascular stiffness and any underlying conditions, as elevated ABPI correlates with increased risk of cardiovascular events and mortality 1.

Key points to consider when evaluating a patient with a raised ABPI include:

• The presence of underlying conditions such as diabetes, chronic kidney disease, or advanced age, which can increase the risk of cardiovascular disease
• The need for comprehensive cardiovascular risk assessment and management
• The importance of early specialist evaluation to establish appropriate monitoring and treatment plans
• The use of additional diagnostic tests such as TBI, duplex ultrasound, or CT angiography to properly assess vascular health.

From the Research

Raised ABPI and Referral to Vascular Specialist

• A raised Ankle-Brachial Pressure Index (ABPI) is associated with an increased risk of cardiovascular events, including myocardial infarction, stroke, and cardiovascular death 2.
• The ABPI test is widely used to screen asymptomatic patients, diagnose patients with clinical symptoms, and monitor patients who have had radiological or surgical intervention 3.
• A high ABPI (≥ 1.4) is a strong indicator of excess risk of cardiovascular events amongst people with peripheral artery disease (PAD) 2.
• The ABPI can be used as a simple tool for assessing cardiovascular risk in patients with systemic vasculitis, with an abnormal ABPI implying an increased risk of cardiovascular disease 4.
• While there is evidence to suggest that a raised ABPI is associated with an increased risk of cardiovascular events, there is no direct evidence to suggest that a raised ABPI necessarily requires referral to a vascular specialist.
• However, given the association between raised ABPI and increased cardiovascular risk, it is likely that patients with a raised ABPI would benefit from referral to a vascular specialist for further evaluation and management 2, 3, 5.

Key Considerations

• The ABPI should be measured according to a consensus statement on the methodology to ensure accurate results 4.
• The ABPI can be used in conjunction with other risk factors to assess cardiovascular risk and guide primary cardiovascular prevention 5.
• ACE inhibitors may possess vasoactive properties that improve symptoms of claudication in patients with lower extremity peripheral artery disease, and may be considered in patients with PAD for cardioprotective effects 6.