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Carotid Stenting: Unanswered Questions and Future Directions

This article delves into the complexities of carotid stenting (CAS) in patients with carotid stenosis, highlighting current knowledge and future inquiries in the field. It discusses the benefits of carotid endarterectomy (CEA) in both symptomatic and asymptomatic patients, especially the elderly and those with severe stenosis. Numerous questions remain unanswered regarding optimal strategies for low-risk symptomatic patients, the safety and efficacy of CAS compared to CEA, and factors influencing stroke risk post-procedure. Insights from current studies and ongoing trials are also reviewed.

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Carotid Stenting: Unanswered Questions and Future Directions

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  1. Carotid Stenting: Unanswered Questions and Future Directions Rod Samuelson, Elad Levy, LN Hopkins University at Buffalo Neurosurgery October 2006

  2. LN Hopkins, MD Potential Conflicts Consultant & research support: Boston Scientific, Cordis, Medtronic, Guidant Financial interests: Boston Scientific EPI, Cordis, J&J, Micrus, Endotex, Access Closure Inc

  3. Carotid StenosisWhat do We Know? In LOW RISK Patients: • CEA is of benefit (greater for Sx pts) • CEA of more benefit with severe stenosis • CEA of more benefit in elderly • CEA must be done safely

  4. Carotid StenosisWhat do We Know? In Asymptomatic Low Risk Patients • CEA is better than medical therepy • CEA prevents strokes in women (ACST) • CEA prevents disabling strokes (ACST) • CEA prevents fatal strokes (ACST)

  5. Carotid StenosisWhat do We Know? In Elderly Patients: • Stroke risk is much higher in elderly pts • CEA greatly benefits elderly low risk pts • CEA risk is increased in elderly patients

  6. Carotid StenosisWhat do We Know? • Definition of High Risk for CEA • CAS risk = CEA in High Risk pts • CAS & CEA risk is higher in elderly pts and in symptomatic pts

  7. Unanswered Questions • Should we treat Symptomatic low risk pts with CAS or CEA? • Embolic protection no/ yes/ what type? • Which is better: Open or Closed cell stents • What training is best for CAS

  8. Unanswered Questions • What is High Risk for CAS ? • Should we treat elderly pts with CAS ? • Are high risk (CEA) pts at higher risk for stroke ?? • The “3% Rule” ????

  9. A Few Helpful Facts…

  10. Asymptomatic Carotid Stenosis and Risk of Stroke Study (ACSRS) Asymptomatic Patients with Medical CoMorbidities And Severe Stenosis… Stroke rate up to 6% per year !! The “3 % Rule” does not apply to High Risk pts Kakkos,Nicolaides et al Int Angiol ’05, 24, 221-30

  11. Elderly Patients(75-79)NASCET Analysis • Absolute risk reduction(ARR) overall = 17% • ARR in pts 75-79 = 30%

  12. Some Stroke Facts… • Only 1/3 of strokes are preceded by TIA Caplan et al • Many TIA’s are never diagnosed Castaldo, Tool et al, Arch neurol, 1997 • Many Stroke are never diagnosed

  13. Stroke Facts… • Silent infarcts (CT&MRI) noted in 12-70% of asx pts (ACST) Halliday • Silent infarcts seen in 15% of ACAS patients

  14. Other “Non Symptom” Symptoms • Neurocognitive function impaired in asymptomatic patients. Raabe, SIR March ’06 • Dizzyness ???

  15. High Risk CAS • Not the same as for CEA • Are CEA and CAS complementary ? • What are identified CAS risk factors? • How to make CAS SAFER ?

  16. Current CAS Results (D/S/MI)High Risk Registries • CAPTURE 6 • CREATE 6 • BEACH 5 • CABERNET 4 • CASES 5

  17. Current CAS ResultsOutliers, But RPCT • SPACE 7 • EVA 3S 10

  18. CAPTURE STROKE COHORT: Summary- Capture 3500 patients • Overall stroke rate = 4.8% • Major stroke rate = 2.0% • Minor stroke rate = 2.9% • Ipsilateral stroke rate= 4.0% • Non-ipsilateral stroke rate= 0.9% (18% of all strokes)

  19. CAPTURE STROKE COHORT: Summary of Strokes • Stroke rate in high risk population is 4.8% • Major stroke rate = 2.0% • Non-ipsilateral represents 18% of strokes of a cumulative 0.9% rate • No non-ipsilateral strokes reported during the procedure • 38% of strokes occurred after 24 hours • 78% of strokes occurred post-procedure and post-discharge

  20. CAPTUREGender & Symptoms • DSMI overall Sx pts 12.2 Asx 5.3 (.0001) • DS (F Worse) Sx F <80 vs Sx M <80 (.03)

  21. CAPTURE Post Market Registry3000 ptsFDA Selection CriteriaOctogenarians • Age > 80 713/3000 pts(24%) • Independent predictors DSMI @ 30 days… • DSMI = 9.4(>80) vs 5.2(<80) • Calcification (mod+) OR 1.39 • Predilitation for filter OR 3.22 stroke alone OR 4.02 • Multiple stents OR 1.77 >80 stroke alone OR3.14

  22. CAPTURE STROKE COHORT: Questions • Why do many strokes occur after the procedure (78%) or after 24 hours (38%)? Would Closed Cell stents be better?? • Why do 18 % occur in a vessel that has not been manipulated? • Does the answer lie in? • Arch Type, calcification and overall plaque morphology • Improved technical equipment • Medical therapy before and after the procedure

  23. CREATE High Risk RegistryEV3 Stent + Spider Filter30 Day Results • 30 day death, stroke and MI 6.2% • Major Stroke 3.5% • Hemorrhage 1.3% • Risk Factors Symptomatic carotid stenosis Renal failure Duration of filter deployment

  24. SPACE TrialRPCT N=1200 Death, Stroke and MI - 30 day CAS 6.8% CEA 6.3% p = 0.09 CEA better in older patients

  25. CAS Risk Factors 1)Symptomatic lesion 2)Sx > age 80 3)Renal Failure 4)Multiple stents 5)Duration Filter deployment 6)Pre dilitation 7)Tortuous/calcified arteries

  26. CASNon Predictors of Risk • Sex ?? CAPTURE • Calcification • Residual stenosis • Filter • Contralateral occlusion • Smoking • Diabetes • Statins

  27. Newer ResultsWhat Do They Mean? • Endarterectomy versus Stenting in Patients with Symptomatic Severe Carotid Stenosis • EVA-3S Trial • New England Journal of Medicine • October 19, 2006

  28. EVA-3S Trial: Results • 30 Day rate of any stroke or death • Endarterectomy = 3.9% • Carotid Stent = 9.6% • Relative Risk of 2.5 (95% CI 1.2 to 5.1) • 30 Day rate of disabling stroke or death • Endarterectomy = 1.5% • Carotid Stent = 3.4% • Relative Risk of 2.2 (95% CI 0.7 to 7.2)*** • Not statistically significant

  29. EVA-3S Trial: Limitations • Distal protection was only “[strongly] recommended” after February 2003 (50% trial duration) • 30 day stroke or death • Without DEP = 25% (5 of 20) • With DEP = 7.9% (18 of 227) • If 7.9% rather than 9.6% is used: • Relative Risk = 2.0 (p = 0.07)

  30. EVA-3S Trial: Limitations • Rates of MI were not assessed • (Reduced rate of MI was one source of benefit identified in the SAPPHIRE Trial) • Only 30 day and 6 month follow up • (Despite trial ongoing since 2000)

  31. EVA-3S Trial: Limitations • Experience bias • Vascular surgeons: • Required 25 CEAs in the year prior to study entry • Endovascular physicians: • Required 12 carotid stents or 35 “supra-aortic stents” with at least 5 carotid stents • Or, Allowed to receive training and credentialing “under supervision” as they enrolled patients in the trial • Allowed to use new stents after only two cases

  32. EVA-3S Trial: Limitations • Enrollment Bias…? • Total CEA case volumes were not discussed • Estimated 15% or less of all patients randomized • Thirty hospitals • Assuming only 1 vascular surgeon per hospital with the enrollment criteria minimum 25 cases/yr • 4.75 years of enrollment = 3562.5 patients

  33. What will CREST teach us that we don’t already know? • CREST: Randomized CAS vs. CEA • Started in 2000, >100 centers • Plans to enroll 2500 patients • Enrollment- around 1700 • 1387 lead-in cases • 789 carotid stents reported in November 2004 • 30 day stroke and death = 4.6% • 30 day MI = 1.1%

  34. What will CREST teach us that we don’t already know? • Differences from EVA-3S • Distal Embolic Protection • MI rates are monitored • Dual antiplatelet therapy in all patients • Long term follow up • More rigorous interventionalist credentialing • CREST is now more important than ever • Challenges to Recruitment are present

  35. Conclusions • CAS and CEA are complementary…the patient must have every technical option • Asymptomatic patients deserve treatment…we don’t know which is best yet • Low-risk patients should be enrolled in further trials! CREST, ACT 1… • We are beginning to understand which pts are at high risk for CAS….AVOID them!!!!

  36. Future Perspectives:The War Against StrokeHow Are We Doing??

  37. Who Will Treat Acute Stroke? • 750,000 CVAs per year and growing • ~ 250 neurointerventionalists • ~ 60 endovascular neurosurgeons • ~ 5 endovascular neurologists • 5,000 interventional cardiologists

  38. How Do We Get There ? • Training • Technology • Collaborating

  39. Barriers • Societal • New Anatomy • Technology

  40. CollaborationSubspecialty Strengths • Neurology • Radiology • Vascular surg • Vascular med • Cardiology • End organ cognitive • Imaging/cath skills • Own CEA market • Cognitive/imaging • Cath/angioplasty skills • Clinicians • Industry partners • Clinical research

  41. We Will Win the War on StrokeAnd…Cardiologists Will Treat Stroke

  42. Simulator Training Model Commercial Pilot • Mandatory yearly training • 60 hours simulated instrument training • 60 hours actual instrument training Col. Chester Griffin Director, Simulator Training AW Certification - USAF

  43. Flight SimulationThree Components • Tactile (haptics) • Procedural • Complications Sound Familiar ??

  44. Mentice Simulator

  45. Illustrative Case • 27 year old female • Cesarean delivery 8 weeks prior • Ground level fall and head impact • No LOC, No seizure • Acute onset right neck and head pain • Left upper extremity weakness • Slurred speech

  46. Illustrative Case • Meds: Oral contraceptives • In ED: NIHSS = 11 • Left facial weakness, dysarthria, left upper extremity weakness, left sided anesthesia • Head CT: no acute trauma • Head CT perfusion…

  47. Original CT Perfusion Time to Peak

  48. Emergent Angiogram

  49. Acute RICA occlusion • Heparin 4000 • ACT >250

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