Carotid Stenting and Transcarotid Artery Revascularization

32.1Definition and clinical presentation

Carotid stenting and transcarotid artery revascularization are endovascular interventions for extracranial carotid artery stenosis. Intervention is considered only after an indication is established based on presenting features, life expectancy, medical therapy, and center peri-procedural outcomes ESVS · 2023 · SVS 2022.

Clinical presentation dictates the primary goal of intervention:

• Symptomatic disease: Patients presenting with recent stroke or transient ischemic attack undergo revascularization primarily to prevent early recurrent stroke.
• Asymptomatic disease: Intervention is prophylactic and depends on a long-term survival benefit that exceeds the immediate peri-procedural risk.

Medical management is foundational for all patients. Baseline therapy includes blood-pressure control, statin administration, smoking cessation, and appropriate antiplatelet therapy regardless of the ultimate procedural decision AHA/ASA 2021. Any stent-based procedure adds dual antiplatelet therapy: aspirin 75 to 325 mg daily plus clopidogrel 75 mg daily, with clopidogrel started several days before the procedure or given as a 300 mg load, continued for at least 30 days after stent placement, then reduced to aspirin monotherapy indefinitely ESVS · 2023 · SVS 2022.

32.2Diagnosis and anatomic stratification

Diagnostic confirmation relies on duplex ultrasound interpreted using consensus velocity and imaging criteria SRU Consensus 2003. The consensus thresholds are explicit: ICA stenosis of 70% or greater corresponds to peak systolic velocity 230 cm/s or higher with end-diastolic velocity 100 cm/s or higher and an ICA/CCA peak-systolic ratio of 4 or greater; 50 to 69% corresponds to peak systolic velocity 125 to 230 cm/s, end-diastolic velocity 40 to 100 cm/s, and an ICA/CCA ratio of 2 to 4; below 50% corresponds to peak systolic velocity under 125 cm/s. Discordance between duplex ultrasound and cross-sectional imaging must be resolved prior to assigning a procedural route.

Anatomic stratification defines the procedural hazards for stent-based therapies. Transfemoral access requires navigation through the iliofemoral system, aortic arch, and great-vessel origins. Arch elongation, heavy atheroma, calcification, severe tortuosity, and common-carotid disease increase embolic risk during transfemoral catheter manipulation ESVS · 2023 · SVS 2022. Transcarotid access bypasses these proximal structures via direct surgical exposure of the common carotid artery in the neck, establishing dynamic flow reversal before the target lesion is crossed VQI TCAR Registry (2020).

32.3Treatment-decision thresholds and modality selection

The choice of revascularization route is evaluated only after the center's peri-procedural stroke and death rates justify intervention over non-operative medical care; the accepted 30-day stroke-or-death ceiling is 6% in symptomatic and 3% in asymptomatic disease ESVS · 2023 · ACC/AHA 2011. Carotid endarterectomy remains the standard comparator for symptomatic patients at standard surgical risk. Intervention is confined to symptomatic stenosis of 50% or greater or asymptomatic stenosis of 70% or greater by the NASCET method, and symptomatic revascularization is performed promptly, ideally within 2 weeks of the index event SVS 2022.

When intervention is indicated, modality selection follows a stepwise evaluation of systemic risk and access anatomy:

1. Decide surveillance versus intervention based on symptoms, stenosis severity, and patient life expectancy.
2. Confirm the indication for a stent-based pathway over open endarterectomy: high systemic surgical risk, or a hostile neck (prior neck irradiation, prior endarterectomy or radical neck dissection, tracheostomy, a high C2-level bifurcation, or contralateral laryngeal nerve palsy) that makes open dissection hazardous.
3. Evaluate the access anatomy. Transfemoral stenting relies on distal filter protection deployed only after the lesion is crossed. Transcarotid revascularization relies on flow reversal established before the plaque is crossed.
4. Select transcarotid revascularization when a stent-based procedure is indicated but transfemoral arch navigation is anatomically hazardous.
5. Defer intervention in patients with prohibitive overall risk, limited life expectancy, or goals of care prioritizing no intervention.

32.4Evidence and landmark trials

Randomized trial evidence for carotid intervention is cohort-specific. Symptomatic European trials consistently demonstrated early peri-procedural hazards for transfemoral stenting compared with endarterectomy. In ICSS, stenting carried higher 30-day rates of stroke, myocardial infarction, or death, with a diffusion-weighted MRI substudy confirming a greater silent embolic burden ICSS MRI Substudy (2010) · ICSS · 2010. EVA-3S was stopped early for excessive 30-day stroke or death after stenting, and SPACE failed to demonstrate non-inferiority for stenting at 30 days EVA-3S (2006) · SPACE · 2006. Long-term follow-up confirms that non-procedural stroke prevention is similar across modalities, isolating the risk difference to the peri-procedural period Cochrane 2020 · ICSS (2015).

In a mixed cohort, CREST reported a similar overall primary composite for stenting and endarterectomy, but the constituent events differed: stenting caused more peri-procedural strokes, whereas endarterectomy caused more myocardial infarctions CREST · 2010. Age functions as a treatment-effect modifier; patients aged 70 years and older experience worse peri-procedural stroke outcomes with stenting CREST (2016).

Transcarotid revascularization rests on single-arm pivotal data, not randomized comparison. ROADSTER established dynamic flow-reversal safety with a 30-day stroke rate of 1.4% and stroke or death of 2.8% in the pivotal cohort, the lowest stroke rate reported for any prospective carotid-stenting trial to that point ROADSTER · 2015. ROADSTER 2, the post-approval study, reported a 30-day stroke rate of 1.9% by intention to treat and 0.6% per protocol, with stroke, death, or myocardial infarction of 3.2% and 1.7% respectively; the gap between the cohorts tracks adherence to the flow-reversal protocol ROADSTER 2 (2020). These single-arm results do not substitute for randomized comparison against endarterectomy.

32.5Areas of controversy

The comparative efficacy of transcarotid artery revascularization directly against carotid endarterectomy remains uncertain. While large administrative registries report superior peri-procedural stroke and death outcomes for transcarotid revascularization compared with transfemoral stenting, these analyses are subject to selection bias and confounding by center experience VQI TCAR Registry (2020). Head-to-head randomized trials directly comparing transcarotid revascularization against endarterectomy are not yet available, complicating the application of registry outcomes to routine standard-risk surgical candidates ESVS · 2023 · SVS 2022.