Diagnostic Approach for Arterial Ischemia/PAD Symptoms

Initial Diagnostic Test

The European Society of Cardiology recommends the ankle-brachial index (ABI) as the initial non-invasive diagnostic test to confirm lower-limb decreased perfusion status in all patients with suspected PAD, with sensitivity of 68-84% and specificity of 84-99% 1, 3, 4
The American College of Cardiology recommends ABI as the first-line test for diagnosing PAD, due to its simplicity, low cost, and wide availability 2, 5
An ABI ≤0.90 confirms the diagnosis of PAD, while values between 0.91-0.99 are borderline, 1.00-1.40 are normal, and >1.40 indicate noncompressible arteries requiring alternative testing 1, 2, 5

If the initial ABI is >1.40 (noncompressible arteries), the European Society of Cardiology recommends measuring toe-brachial index (TBI) with waveforms as the next test, with TBI <0.70 considered abnormal 1, 2, 5
If the resting ABI is normal (>0.90) but clinical suspicion remains high due to exertional leg symptoms, the American College of Cardiology recommends performing post-exercise ABI testing, preferably by treadmill, with a post-exercise ABI decrease of >20% serving as a diagnostic criterion for PAD 1, 2, 5
If chronic limb-threatening ischemia (CLTI) is suspected with rest pain, non-healing wounds, or gangrene, additional perfusion measures beyond ABI should be obtained, including toe pressure, TcPO2, or skin perfusion pressure 1, 2, 3

The European Society of Cardiology recommends duplex ultrasound as the first-line imaging method only after ABI screening has been performed, not as the initial diagnostic test 1, 3
CT angiography should not be performed as an initial diagnostic test for suspected PAD, but is recommended as adjuvant imaging in symptomatic patients with aorto-iliac or multisegmental/complex disease when revascularization is being planned 1, 2, 3
Anatomic imaging with CTA (or MRA) is reserved for highly symptomatic patients in whom the diagnosis has already been established and intervention is being considered 2, 5

The American College of Cardiology recommends not skipping ABI and proceeding directly to imaging studies unless there is an urgent need for revascularization planning in a patient with obvious critical limb ischemia 2
The European Society of Cardiology recommends not relying on ABI alone in diabetic patients or those with renal failure, as medial arterial calcification can produce falsely elevated values; measure TBI in these populations even if resting ABI appears normal 1, 2
The American College of Cardiology recommends not ordering CT angiography for asymptomatic PAD or for patients who are not revascularization candidates, as anatomic imaging is not indicated without a plan for intervention 2