Early observations and pilot data that first suggested a new direction
Carotid endarterectomy (CEA) was established as the definitive treatment for symptomatic carotid stenosis by two landmark trials. The North American Symptomatic Carotid Endarterectomy Trial (NASCET) demonstrated that CEA reduced the risk of ipsilateral stroke from 26% to 9% over 2 years in patients with 70-99% symptomatic stenosis, representing an absolute risk reduction of 17%. The European Carotid Surgery Trial (ECST) confirmed these findings. For asymptomatic stenosis, ACAS (1995) and ACST (2004) showed more modest but significant benefits of CEA over medical therapy alone. These trials established CEA as one of the most evidence-based operations in surgery, though the medical therapy arms of these 1990s trials would be considered suboptimal by modern standards.
Landmark RCTs and pivotal trials that established the evidence base
Carotid artery stenting (CAS) emerged as a less invasive alternative, and several major trials compared it to CEA. The CREST trial (2502 patients) was the most influential, showing no significant difference in the composite endpoint of periprocedural stroke, MI, or death plus ipsilateral stroke at 4 years. However, the trials revealed important nuances: CAS had a higher rate of periprocedural stroke, while CEA had a higher rate of periprocedural MI. The ICSS trial showed higher stroke rates with CAS at 120 days. Long-term CREST follow-up to 10 years confirmed equivalent outcomes. Importantly, patient age emerged as a key modifier—patients over 70 had better outcomes with CEA, while younger patients did equally well with either approach. These trials established CAS as an acceptable alternative to CEA in selected patients.
Follow-up studies, subgroup analyses, and real-world validation
The most important recent development has been the recognition that modern best medical therapy (BMT) may be so effective that neither CEA nor CAS provides incremental benefit for asymptomatic stenosis. The ACST-2 trial (3625 patients) compared CEA to CAS in asymptomatic patients and found equivalent procedural risk between the two techniques, but did not include a medical therapy-only arm. The CREST-2 trial was designed to answer the critical question of whether any revascularization adds benefit to modern BMT for asymptomatic carotid stenosis, with results eagerly awaited. Observational data suggest the annual stroke risk with modern medical therapy (intensive statin therapy, antihypertensives, antiplatelets) has fallen to <1% per year for asymptomatic stenosis, compared to the 2-3% annual risk in the ACAS/ACST era, potentially negating the benefit of prophylactic revascularization.
Integration into clinical practice guidelines and recommendations
Current guidelines strongly recommend CEA for symptomatic carotid stenosis >50% (NASCET criteria) within 2 weeks of symptoms, performed by surgeons with <6% complication rates. For asymptomatic stenosis, guidelines are evolving. The SVS 2022 guidelines recommend revascularization for asymptomatic stenosis >70% in patients with reasonable life expectancy, but increasingly emphasize risk stratification—identifying the 'vulnerable' asymptomatic plaque that warrants intervention versus the stable plaque best managed medically. The ESC/ESVS guidelines recommend CEA over CAS for most patients, with CAS reserved for those with hostile necks, prior ipsilateral CEA, or radiation-induced stenosis. Timing of intervention after acute stroke is also emphasized—early CEA within 14 days of symptoms provides the greatest benefit.
Society for Vascular Surgery (SVS) Clinical Practice Guidelines
CEA preferred over CAS for most symptomatic patients; revascularization within 14 days of symptoms; for asymptomatic stenosis >70%, consider revascularization if perioperative risk <3% and life expectancy >5 years
ESC/ESVS Guidelines on Carotid and Vertebral Artery Disease
CEA recommended as first-line for symptomatic stenosis 50-99%; CAS acceptable alternative in selected patients; asymptomatic disease requires risk stratification beyond stenosis degree
Now
Current standard of care and ongoing research directions
Carotid revascularization is at an inflection point. For symptomatic stenosis, CEA within 14 days remains the gold standard, with CAS as a proven alternative for selected patients. The major controversy is in asymptomatic disease, where modern medical therapy has dramatically reduced stroke risk, potentially diminishing the incremental benefit of prophylactic revascularization. CREST-2 results are expected to clarify this question. Meanwhile, research focuses on identifying high-risk asymptomatic plaques using imaging biomarkers (MRI plaque characterization, contrast-enhanced ultrasound, intraplaque hemorrhage) to select patients who would benefit from intervention. Transcarotid artery revascularization (TCAR) with flow reversal has emerged as a hybrid approach offering the stenting advantage with reduced embolic risk, with growing evidence from the ROADSTER trials.
Should asymptomatic carotid stenosis still be treated surgically in the era of modern medical therapy?+
This is the most contested question in vascular surgery today. The original ACAS and ACST trials showed benefit for CEA when background stroke risk was 2-3% per year with 1990s medical therapy. Modern BMT (high-dose statins, antihypertensives, antiplatelets) has reduced this to <1% per year. If the annual stroke risk on medical therapy is <1% and perioperative risk is 1-3%, the net benefit of surgery is marginal. CREST-2 is designed to answer this definitively. Until results are available, risk stratification using imaging biomarkers to identify vulnerable plaques is increasingly used to guide intervention.
When should CAS be preferred over CEA?+
CAS is generally preferred over CEA when surgical access is difficult: hostile neck (prior radical neck dissection, radiation therapy), high carotid bifurcation, contralateral vocal cord paralysis, previous ipsilateral CEA with restenosis, or severe cardiopulmonary comorbidity making general anesthesia high-risk. Age >70 favors CEA due to higher CAS stroke rates in elderly patients (likely related to aortic arch disease and vessel tortuosity). TCAR (transcarotid artery revascularization) with flow reversal is emerging as a hybrid option for high surgical risk patients.
What is the importance of timing of CEA after symptomatic events?+
The benefit of CEA is time-dependent and maximal when performed within 2 weeks of symptoms. Analysis of pooled NASCET and ECST data showed NNT of 5 when CEA was performed within 2 weeks versus NNT of 125 when delayed beyond 12 weeks. The stroke risk is highest in the first 48-72 hours after TIA or minor stroke. Current guidelines recommend CEA within 14 days of symptoms. Delaying surgery for 'optimization' may paradoxically increase risk by exposing patients to the highest-risk period without treatment.
