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CASONI

Carotid Artery Stenting Outcomes by Neurointerventional Surgeons

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Year of Publication: 2025

Authors: Mohamad Ezzeldin, Ameer E. Hassan, Ali Kerro, ..., Raul G. Nogueira

Journal: Stroke: Vascular and Interventional Neurology

Citation: Stroke Vasc Interv Neurol. 2025;5:e001459. DOI: 10.1161/SVIN.124.001459

Link: https://www.ahajournals.org/doi/10.1161/SVIN.124.001459

PDF: https://www.ahajournals.org/doi/reader/1...SVIN.124.001459

Clinical Question

What are the complication rates of carotid artery stenting (CAS) when performed by fellowship-trained neurointerventionalists (NIRs)?

Bottom Line

Carotid artery stenting performed by fellowship-trained neurointerventionalists had a low rate of major complications, suggesting safety and effectiveness in specialized stroke centers.

        Major Points
        CASONI is the largest contemporary registry of carotid artery stenting (CAS) outcomes specifically performed by fellowship-trained neurointerventionalists — 1,445 procedures at 17 US centers (2018-2022).
30-day primary complication rate of 1.8% (stroke, ICH, MI, or death) — substantially below the CMS-mandated threshold of 3% for symptomatic and 2-3% for asymptomatic carotid stenosis.
Technical success rate of 99.52% — among the highest reported in any CAS series, reflecting the expertise of dedicated neurointerventionalists.
Embolic protection devices (EPDs) used in 94.25% of cases — near-universal EPD use represents modern best practice and likely contributed to low stroke rates.
Multivariate predictors of complications: age >73 years, female sex, type 3 aortic arch (bovine or tortuous), and low diastolic BP. These define the 'high-risk for CAS' subgroup.
Context: published during ongoing CREST-2 enrollment, which randomizes asymptomatic carotid stenosis to revascularization vs medical therapy. CASONI supports that CAS in expert hands meets safety benchmarks.
Challenges the narrative from EVA-3S and ICSS that CAS has unacceptably high stroke rates — those trials used operators with variable experience, whereas CASONI required fellowship-trained NIRs.
Ischemic stroke rate was only 0.55%, hemorrhagic stroke 0.28%, and MI 0.07% — each individual component was remarkably low.
Important limitation: retrospective registry with no randomized comparator (CEA arm). Cannot directly compare outcomes to endarterectomy at the same centers.
Supports operator volume and training as key determinants of CAS safety — consistent with AHA/ASA recommendations that CAS be performed at high-volume centers by experienced operators.

      

Design

Study Type: Multicenter retrospective cohort study

Randomization:

Enrollment Period: 2018–2022

Follow-up Duration: 30 days (primary endpoint); limited long-term data

Centers: 17

Countries: USA

Sample Size: 1445

Analysis: Descriptive statistics, chi-square tests, Welch’s t-tests, and sensitivity analysis using multivariate imputation

Inclusion Criteria

Age ≥18 years.
Carotid artery stenting for atherosclerotic carotid stenosis (symptomatic or asymptomatic).
Procedure performed by a fellowship-trained neurointerventionalist (NIR) at a participating center.
Consecutive cases to minimize selection bias.

Exclusion Criteria

Carotid stenting for non-atherosclerotic indications: dissection, trauma, carotid web, fibromuscular dysplasia, pseudoaneurysm.
Tandem lesion treatment during acute stroke thrombectomy (different clinical scenario with higher baseline risk).
Carotid stenting performed by non-NIR operators at the same centers.
Incomplete 30-day follow-up data (excluded from primary analysis).
Radiation-induced carotid stenosis (different pathophysiology and tissue quality).
Combined carotid-coronary procedures (confounded by cardiac procedural risk).

Baseline Characteristics

Characteristic	Comorbidities	Qualifying Event
Hypertension	86.1
Diabetes	40.2
Hyperlipidemia	74.1
Prior Stroke	52.4
Smoker	65.7

Arms

Field	CAS by NIR
Intervention	Carotid artery stenting with use of embolic protection devices; performed by fellowship-trained neurointerventionalists
Duration	Periprocedural

Outcomes

Outcome	Type	Intervention
Composite of 30-day death, symptomatic ischemic stroke, symptomatic intracranial hemorrhage (ICH), or myocardial infarction (MI)	Primary	1.8%
Non-primary stroke-related complications (TIA, asymptomatic ICH, dissection, in-stent thrombosis, access complications)	Secondary	Various (all <1%)
Death	Adverse	0.9%
Ischemic Stroke	Adverse	0.55%
Hemorrhagic Stroke	Adverse	0.28%
Myocardial Infarction	Adverse	0.07%
TIA	Adverse	0.42%
In-stent Thrombosis	Adverse	0.48%
Dissection	Adverse	0.35%

Criticisms

Retrospective registry design with no control group (no CEA comparator arm) — cannot determine if CAS outcomes are better or worse than endarterectomy at the same centers.
No independent core laboratory or external adjudication of complications — event reporting relied on local investigators, introducing potential ascertainment bias (underreporting).
Only 30-day follow-up — does not capture late in-stent restenosis (peak at 1-2 years), late ipsilateral stroke, or long-term durability of the stent.
Predominantly symptomatic patients (93%) — the 7% asymptomatic subgroup is far too small to draw conclusions about asymptomatic CAS, which is the most controversial indication.
Selection bias inherent in a registry — operators may have selected favorable anatomy patients for CAS and referred unfavorable anatomy to CEA, inflating CAS success rates.
All operators were fellowship-trained NIRs at high-volume academic centers — results cannot be extrapolated to community hospitals or less experienced operators.
No comparison with modern optimal medical therapy alone — CREST-2 will determine if any revascularization (CAS or CEA) is needed for asymptomatic stenosis in the statin era.
Missing data on antiplatelet regimen, statin use, and other medical optimization — these confounders could significantly affect periprocedural outcomes.
HCA Healthcare funding and multiple industry-affiliated authors raise potential conflicts of interest in reporting favorable CAS outcomes.

Funding

No specific funding; supported in part by HCA Healthcare; views expressed do not necessarily reflect HCA's views

Based on: CASONI (Stroke: Vascular and Interventional Neurology, 2025)