PDF: CASONI
(2025)Objective
Carotid Artery Stenting Outcomes by Neurointerventional Surgeons.
Study Summary
• Perioperative stroke, death, and myocardial infarction were lower than rates reported in major CAS and CEA trials.
• CAS by fellowship-trained neurointerventionalists in stroke centers showed superior safety outcomes.
Intervention
Multicenter, retrospective observational study across 17 comprehensive stroke centers in the US. N=1445 patients underwent carotid artery stenting by 38 fellowship-trained neurointerventionalists (neurologists, neurosurgeons, neuroradiologists). Primary outcome: 30-day composite of death, symptomatic ischemic stroke, symptomatic ICH, or MI. Secondary outcomes: TIA, access complications, dissection, nonperiprocedural mortality, and others. Technical success, procedural details (EPD use, stent type, anesthesia), and statistical correlations were assessed.
Inclusion Criteria
• Adults undergoing CAS for symptomatic (≥50%) or asymptomatic (≥70%) carotid stenosis
• CAS performed for atherosclerotic disease (not dissection, trauma, or tandem lesions)
Study Design
Arms: Single-arm cohort (all patients underwent CAS by NIRs)
Patients per Arm: 1445 (1281 with complete 30-day data)
Outcome
- Death: 0.9%
- Symptomatic ischemic stroke: 0.55%
- Symptomatic ICH: 0.28%
- Myocardial infarction: 0.07%
• Secondary outcomes (2.84%):
- Access site complications (0.55%)
- TIA (0.42%), asymptomatic ICH (0.35%), carotid dissection (0.35%)
• Predictors of complications:
- Female sex (P=0.013)
- Age >73 (P=0.001)
- Type 3 aortic arch (P=0.01)
- Low diastolic BP during stenting (P=0.04)
• Technical success rate: 99.5%
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.
Study Design
- Study Type
- Multicenter retrospective cohort study
- Randomization
- No
- Sample Size
- 1445
- Follow-up
- 30 days (primary endpoint); limited long-term data
- Centers
- 17
- Countries
- USA
Primary Outcome
Definition: Composite of 30-day death, symptomatic ischemic stroke, symptomatic intracranial hemorrhage (ICH), or myocardial infarction (MI)
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| 1.8% | - |
Limitations & 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.
Citation
Stroke Vasc Interv Neurol. 2025;5:e001459. DOI: 10.1161/SVIN.124.001459