Carotid Stenosis: From Diagnosis to Revascularization
Carotid artery stenosis accounts for approximately 10-15% of all ischemic strokes, typically through artery-to-artery embolism. Management has evolved dramatically — from an era where revascularization was the default, to today’s paradigm where intensive medical therapy forms the foundation of care and revascularization is reserved for carefully selected patients.
The landmark CREST-2 trial in 2025 fundamentally reshaped our approach: intensive medical therapy alone achieved 94% stroke-free survival at 4 years, raising the bar for when intervention adds meaningful benefit.
🔹 Bottom Line: Carotid Stenosis Management
- Symptomatic stenosis ≥50%: Revascularization (CEA or CAS) remains standard of care; both procedures have comparable long-term efficacy
- Asymptomatic stenosis: Intensive medical therapy is highly effective and should be the foundation for ALL patients; revascularization offers only modest incremental benefit (NNT ~31) — patient selection is critical
- Tandem occlusions: Emergent carotid stenting during thrombectomy improves functional outcomes
- The question is no longer “stent or not?” — it’s “who will benefit most?”
Definitions: Symptomatic vs. Asymptomatic Stenosis
The distinction between symptomatic and asymptomatic carotid stenosis is fundamental to management decisions, as the natural history and treatment benefit differ substantially.
Symptomatic Carotid Stenosis
- TIA or stroke in the ipsilateral carotid territory (within 6 months or 180 days)
- Amaurosis fugax (transient monocular vision loss)
- Embolic-pattern infarcts on CT/MRI — scattered cortical infarcts, watershed involvement
Annual stroke risk with symptomatic stenosis ≥70% is approximately 10-15% without intervention.
Asymptomatic Carotid Stenosis
- No neurological events in the carotid territory
- Often discovered incidentally (carotid bruit, screening ultrasound, preoperative workup)
- Annual stroke risk on modern medical therapy is approximately 1-2%
Measuring Carotid Stenosis
Two measurement methods exist, which can create confusion when interpreting trials.
| Method | Reference Point | Key Trials |
|---|---|---|
| NASCET | Distal normal ICA | NASCET, ACAS, CREST |
| ECST | Estimated original bulb diameter | ECST |
The NASCET method yields lower percentage values. Rough conversion: ECST 70% ≈ NASCET 50%; ECST 80% ≈ NASCET 70%. NASCET method is now standard.
Ultrasound Criteria
| Stenosis (NASCET) | Peak Systolic Velocity | End Diastolic Velocity | ICA/CCA PSV Ratio |
|---|---|---|---|
| <50% | <125 cm/s | <40 cm/s | <2.0 |
| 50-69% | 125-230 cm/s | 40-100 cm/s | 2.0-4.0 |
| ≥70% | >230 cm/s | >100 cm/s | >4.0 |
Symptomatic Carotid Stenosis
Landmark Endarterectomy Trials
The NASCET trial (1991) established CEA benefit for symptomatic stenosis. For severe stenosis (≥70%), CEA reduced 5-year ipsilateral stroke risk from 26% to 9% — a 65% relative risk reduction (NNT 7-8). For moderate stenosis (50-69%), the benefit was smaller: 30% RRR, NNT 15.
The ECST trial (1998) confirmed CEA benefit for >80% stenosis (ECST criteria), though the perioperative stroke/death rate was 7%.
🔹 Clinical Relevance: Timing of CEA After Stroke
CEA vs. Carotid Artery Stenting
Three major trials established that CEA and CAS have comparable long-term efficacy with different periprocedural risk profiles.
The CREST trial (2010) found no difference in the composite endpoint of stroke, MI, or death. However, stroke was more common with CAS (4.1% vs. 2.3%), while MI was more common with CEA (2.3% vs. 1.1%). Age modified the effect — patients <70 years had better outcomes with CAS, while those ≥70 fared better with CEA.
The ICSS trial (2015) showed identical 5-year disabling stroke rates (6.4% vs. 6.5%), though overall any-stroke rate was higher with CAS (15.2% vs. 9.4%).
The SPACE trial (2008) found similar 2-year stroke rates but significantly higher restenosis with CAS (10.7% vs. 4.6%).
🔹 Clinical Relevance: Choosing CEA vs. CAS
- Both procedures are effective — long-term stroke prevention is comparable
- Favor CEA: Age >70, unfavorable arch anatomy, heavily calcified lesions
- Favor CAS: Age <70, high surgical risk, hostile neck (prior surgery, radiation), high cervical lesion (at/above C2 or angle of mandible)
- Periprocedural risk should be <6% for symptomatic stenosis
Asymptomatic Carotid Stenosis
Historical Trials
The ACAS (1995) and ACST (2004) trials established CEA benefit for asymptomatic stenosis ≥60%, showing 5-year absolute risk reductions of 5.9% and 5.3% respectively (NNT ~17). However, both trials predate modern medical therapy — statin use was low, BP targets were less aggressive, and the annual stroke risk in medical arms (~2%) exceeds what contemporary treatment achieves.
The Modern Era: CREST-2 and ECST-2
The CREST-2 trial (2025) compared revascularization plus intensive medical management (IMM) versus IMM alone:
- Stenting trial: 4-year stroke/death was 2.8% vs. 6.0% — statistically significant, but NNT = 31
- CEA trial: 4-year stroke/death was 3.7% vs. 5.3% — not statistically significant
- Key insight: Medical therapy alone achieved 94-95% stroke-free survival at 4 years — and this was with suboptimal target achievement (BP at goal in ~70%, LDL at goal in ~67%), suggesting even better outcomes may be possible with stricter adherence
The ECST-2 trial (2025) found no benefit of revascularization in patients with <20% 5-year stroke risk (CAR score).
🔹 Intensive Medical Therapy Targets
| Target | Goal |
|---|---|
| Blood pressure | <130/80 mmHg |
| LDL cholesterol | <70 mg/dL (consider <55 mg/dL if very high risk) |
| Antiplatelet | Aspirin 81-325 mg daily (or clopidogrel if intolerant) |
| Diabetes | HbA1c <7% (individualized) |
| Smoking | Complete cessation |
| Lifestyle | Mediterranean diet, regular exercise, weight optimization |
Who Should Be Considered for Revascularization?
After CREST-2, the question is no longer “stent or not?” — it’s “who will benefit most?” Revascularization should be selective, focused on higher-risk patients.
🔴 Candidates for Revascularization in Asymptomatic Stenosis
1️⃣ High-Risk Plaque Features
- Ulcerated plaque on imaging
- Intraplaque hemorrhage (on MRI)
- Microembolic signals on transcranial Doppler
- Silent ipsilateral embolic infarcts on MRI
- Rapid progression despite optimal medical therapy
2️⃣ Patient-Related Factors
- Reasonable life expectancy (>5-10 years)
- Few competing comorbidities
- Failure or intolerance of medical therapy (e.g., refractory BP, statin intolerance)
3️⃣ Procedure-Related Factors
- Expected periprocedural stroke/death risk <2-3%
- High-volume center with experienced operators and transparent outcomes
Revascularization Techniques: CEA vs. Transfemoral CAS vs. TCAR
Choosing Between CEA and Transfemoral CAS
| Factor | Favors CEA | Favors Transfemoral CAS |
|---|---|---|
| Age | >70 years | <70 years |
| Neck anatomy | Accessible, no prior surgery | Hostile neck (prior CEA, radiation) |
| Lesion location | Standard carotid bulb | High cervical (at/above C2 or angle of mandible) |
| Cardiac risk | Low surgical risk | High cardiac risk (recent MI, unstable angina) |
| Aortic arch | Any | Type I-II arch, minimal tortuosity |
| Lesion characteristics | Long segment, heavy calcification | Focal stenosis, minimal calcification |
Transcarotid Artery Revascularization (TCAR)
TCAR combines direct surgical carotid access with stenting, using dynamic flow reversal for neuroprotection. By avoiding aortic arch navigation, it eliminates the primary source of embolic complications during transfemoral CAS.
The ROADSTER trials established TCAR safety: the original trial (2015) reported a 1.4% stroke rate in high-surgical-risk patients — the lowest for any prospective CAS trial. ROADSTER 2 (2020) confirmed these results with a 0.6% stroke rate in 632 patients, and ROADSTER 3 (2024) extended the indication to standard-risk patients with a 0.9% composite stroke/death/MI rate.
🔹 TCAR: Advantages and Limitations
Advantages:
- Avoids aortic arch manipulation — reduces embolic risk
- Flow reversal provides superior neuroprotection vs. distal filters
- Suitable for hostile neck where CEA is high-risk
- Lower cranial nerve injury than CEA (~0.6-1.3%)
Limitations:
- Requires surgical neck exposure (not purely endovascular)
- Less suitable for proximal CCA disease
- Flow reversal tolerance must be confirmed (contralateral disease requires assessment of collateral adequacy)
- Not widely available at all centers
Tandem Occlusions: Carotid Stenosis During Acute Thrombectomy
Definition
Tandem occlusions — cervical ICA occlusion/stenosis (>70%) with concurrent intracranial LVO — occur in 10-20% of anterior circulation strokes undergoing EVT.
Evidence for Emergent Carotid Stenting
The STRATIS Tandem Lesion analysis (2019) showed good outcome (mRS 0-2) in 68.5% with acute stenting versus 42.2% without (P=0.003), with no increase in symptomatic ICH.
The GSR Tandem Lesions study (2021) confirmed better outcomes with acute ICA treatment (mRS 0-2: 39.5% vs. 29.3%), lower mortality (17.1% vs. 27.1%), and higher reperfusion rates (88.3% vs. 62.8%). The intracranial-first approach achieved faster reperfusion.
The CERES-TANDEM study (2026) is the largest analysis (4,053 patients), showing emergent stenting improved mRS distribution (OR 1.31, P<0.001) with 3-fold higher successful recanalization.
The Emergent Stenting After IVT study (2019) confirmed safety of stenting after IV thrombolysis (sICH 5% vs. 8%, P=0.54).
🔹 Clinical Relevance: Approach to Tandem Lesions
- Acute stenting improves outcomes — should be the default in most cases
- Intracranial-first approach is often preferred — faster cerebral reperfusion
- IV thrombolysis is NOT a contraindication to emergent stenting
- Consider angioplasty alone for dissection-related occlusions
Trial Comparison Tables
Symptomatic Carotid Stenosis Trials
| Trial | Year | N | Comparison | Key Outcome |
|---|---|---|---|---|
| NASCET | 1991 | 2,267 | CEA vs. medical | ≥70%: 65% RRR, NNT 7-8 |
| ECST | 1998 | 3,000 | CEA vs. medical | >80%: 3-yr stroke 14.9% vs. 26.5% |
| CREST | 2010 | 2,502 | CAS vs. CEA | Similar composite; CAS more stroke, CEA more MI |
| ICSS | 2015 | 1,710 | CAS vs. CEA | 5-yr disabling stroke identical (6.4%) |
| SPACE | 2008 | 1,200 | CAS vs. CEA | 2-yr stroke similar; higher restenosis with CAS |
Asymptomatic Carotid Stenosis Trials
| Trial | Year | N | Comparison | Key Outcome |
|---|---|---|---|---|
| ACAS | 1995 | 1,659 | CEA vs. medical | 53% RRR, NNT 17 at 5 years |
| ACST | 2004 | 3,120 | CEA vs. medical | 5.3% ARR at 5 years |
| CREST-2 | 2025 | 2,485 | Stenting/CEA + IMM vs. IMM | Stenting: 2.8% vs. 6.0% (NNT 31); CEA: NS |
| ECST-2 | 2025 | 428 | Revasc + OMT vs. OMT | No benefit in low-risk patients |
TCAR Trials
| Trial | Year | N | Population | 30-Day Stroke Rate |
|---|---|---|---|---|
| ROADSTER | 2015 | 141 | High surgical risk | 1.4% |
| ROADSTER 2 | 2020 | 632 | High surgical risk | 0.6% |
| ROADSTER 3 | 2024 | 344 | Standard surgical risk | 0.9% (composite) |
Tandem Occlusion Studies
| Study | Year | N | Comparison | Key Outcome |
|---|---|---|---|---|
| STRATIS Tandem | 2019 | 147 | Stenting vs. no stent | mRS 0-2: 68.5% vs. 42.2% |
| GSR Tandem | 2021 | 874 | ICA treatment vs. not | mRS 0-2: 39.5% vs. 29.3% |
| CERES-TANDEM | 2026 | 4,053 | eCAS vs. no stent | mRS shift OR 1.31 |
References
- NASCET Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med. 1991.
- European Carotid Surgery Trialists’ Collaborative Group. Lancet. 1998.
- Executive Committee for the ACAS Study. JAMA. 1995.
- Halliday A, et al. ACST. Lancet. 2004.
- Brott TG, et al. CREST. N Engl J Med. 2010.
- Bonati LH, et al. ICSS. Lancet. 2015.
- SPACE Collaborative Group. Lancet. 2006.
- Brott TG, et al. CREST-2. N Engl J Med. 2025.
- Bonati LH, et al. ECST-2. Lancet. 2025.
- Kwolek CJ, et al. ROADSTER. J Vasc Surg. 2015.
- Kashyap VS, et al. ROADSTER 2. J Vasc Surg. 2020.
- Malas MB, et al. ROADSTER 3. J Vasc Surg. 2024.
- Maus V, et al. STRATIS Tandem. Stroke. 2019.
- Maus V, et al. GSR Tandem. Stroke. 2021.
- CERES-TANDEM Investigators. 2026.
- Zhu F, et al. TITAN. JAMA Neurol. 2019.