What are the recommended diagnostic criteria for carotid artery stenosis in patients presenting with transient ischemic attacks?

The recommended diagnostic criteria for carotid artery stenosis in patients presenting with transient ischemic attacks (TIAs) involve a combination of clinical assessment and imaging modalities focused on quantifying the degree of luminal narrowing. Initial evaluation should include a detailed clinical history and neurological examination to confirm the diagnosis of TIA and exclude mimics ¹.

Imaging is essential to assess carotid artery stenosis, with duplex ultrasound being the first-line diagnostic tool due to its non-invasive nature and ability to estimate stenosis severity by measuring peak systolic velocity (PSV), end-diastolic velocity (EDV), and the internal carotid artery to common carotid artery velocity ratio. Specific velocity thresholds correlate with stenosis severity: a PSV >125 cm/s generally indicates ≥50% stenosis, and higher velocities correspond to more severe stenosis ¹.

Confirmatory imaging with CT angiography (CTA) or MR angiography (MRA) is recommended when ultrasound results are inconclusive or when surgical intervention is considered, to provide detailed anatomical visualization and precise measurement of stenosis. These modalities help differentiate symptomatic from asymptomatic lesions and guide management decisions ¹.

According to recent literature, non-stenotic carotid plaques (<50% stenosis) can still be prevalent in patients with acute ischemic stroke and TIA, highlighting the importance of plaque morphology and vulnerability assessment beyond luminal narrowing alone (Ospel et al., 2020). This suggests that while stenosis quantification remains central, adjunctive imaging assessing plaque characteristics may enhance risk stratification.

Furthermore, the decision for carotid endarterectomy in symptomatic patients is primarily based on the degree of stenosis (usually ≥50% symptomatic stenosis), clinical presentation, and timing from the event, as supported by both NICE guidelines and surgical outcome studies (Rerkasem et al., 2020; Pini et al., 2023) ¹.

In summary, the diagnostic criteria for carotid artery stenosis in TIA patients integrate clinical assessment with duplex ultrasound velocity criteria, supplemented by CTA or MRA as needed, with emerging evidence supporting consideration of plaque characteristics beyond stenosis severity.