What are the types of stents used for carotid stenting, their indications, and the positive and negative aspects of the procedure?

Types of Carotid Stents and Their Clinical Applications

Primary Stent Categories

Carotid stents are fundamentally classified by their cell design (open-cell vs. closed-cell) and material composition (nitinol vs. cobalt-chromium/Elgiloy), with each design offering distinct advantages for specific anatomical and lesion characteristics. 1

Open-Cell Design Stents

• Open-cell stents provide superior flexibility and conformability, making them the preferred choice when treating tortuous carotid anatomy 1
• These stents adapt better to vessel curves and irregular anatomy due to their flexible strut configuration 1
• The major disadvantage is reduced plaque coverage, which theoretically increases the risk of distal embolization through the larger cell openings 1
• Open-cell designs are less suitable for high-risk, friable lesions with suspected high embolic potential 1

Closed-Cell Design Stents

• Closed-cell stents offer superior plaque coverage and scaffolding, making them the optimal choice for lesions with high embolic risk (soft, ulcerated, thrombus-containing, or tight stenoses) 1, 2
• In the TARGET-CAS study, closed-cell stents were used in 82.4% of high-risk lesion procedures, demonstrating their preferential selection for embolic protection 2
• The trade-off is reduced flexibility, making them less suitable for highly tortuous anatomy 1
• These stents provide better radial force and more complete lesion coverage 1

Material-Based Classification

Nitinol stents are preferred for highly calcified lesions due to their superior radial force and ability to expand against rigid plaque 1

Cobalt-chromium (Elgiloy) stents or tapered nitinol designs are selected when significant diameter mismatch exists between the common carotid artery and internal carotid artery 1

Newer Generation: Micromesh Stents

• Micromesh stents represent an emerging technology combining excellent flexibility with enhanced embolic protection through their dual-layer design 3
• These stents aim to address the limitations of both open-cell and closed-cell designs by providing both conformability and plaque sequestration 4, 3
• The dual-layer design may reduce continued intra-stent plaque growth, a recognized limitation of first-generation single-layer stents 4

Clinical Indications by Stent Type

For Tortuous Anatomy

Select open-cell, flexible stents to navigate complex vessel geometry without kinking or incomplete apposition 1

For High-Risk Embolic Lesions

Select closed-cell stents when treating symptomatic patients with soft plaques, ulcerated lesions, thrombus-containing stenoses, or tight stenoses (>80%) 1, 2

For Calcified Lesions

Select nitinol stents to achieve adequate radial force for lesion expansion against rigid, calcified plaque 1

For Diameter Mismatch

Select cobalt-chromium or tapered nitinol stents when the common carotid artery diameter significantly exceeds the internal carotid artery diameter 1

Critical Performance Requirements

Regardless of stent type selected, operator and center performance must demonstrate periprocedural stroke/death rates <6% for symptomatic patients and <3% for asymptomatic patients 5, 6

• The 2024 ESC guidelines emphasize that CAS should only be performed when these thresholds can be reliably achieved 4
• Age >70 years is a relative contraindication to stenting, as endarterectomy demonstrates superior outcomes in this population (1% vs 3% stroke risk) 5

The Tailored-CAS Algorithm

In approximately 75% of procedures, stent type selection does not significantly impact outcomes; however, for the remaining 25%, careful preoperative assessment is mandatory 1

The TARGET-CAS study validated this approach, achieving a 30-day complication rate of only 2.38% by using:

• Extracranial ultrasound and CT angiography for lesion characterization 2
• Preferential use of closed-cell stents (76.2%) and proximal embolic protection devices (34.8%) in symptomatic patients 2
• Closed-cell stents in 82.4% of high-risk lesions 2

Common Pitfalls to Avoid

Never use velocity criteria for non-stented arteries when monitoring in-stent restenosis post-CAS, as this leads to significant overestimation of stenosis 4

Avoid single-layer stents in lesions with high atherosclerotic burden, as they may fail to effectively sequestrate plaque and allow continued intra-stent disease progression 4

Do not accept >50% residual stenosis after stent deployment, as this is a principal angiographic risk factor for subsequent restenosis 4

Mandatory Adjunctive Therapy

All patients undergoing CAS require dual antiplatelet therapy (aspirin plus clopidogrel) for at least 1 month post-procedure, regardless of stent type 4, 6

Optimal medical therapy including high-intensity statin therapy, blood pressure control, and risk factor modification is mandatory and takes precedence over the technical aspects of stent selection 5, 6