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Title: Assessment: Carotid Endarterectomy An EvidenceBased Review


1
Assessment Carotid Endarterectomy?An
Evidence-Based Review
  • Report of the Therapeutics and Technology
    Subcommittee of the American Academy of
    Neurology
  • S Chaturvedi MD, A Bruno MD, T Feasby MD, R
    Holloway MD, O Benavente MD, SN Cohen MD, R Cote
    MD, D Hess MD, J Saver MD, JD Spence MD, B Stern
    MD, J Wilterdink MD
  • Published in Neurology 200565794-801

2
Objective
  • The objective of this report is to provide an
    updated statement on the efficacy of carotid
    endarterectomy (CE) for stroke prevention in
    asymptomatic and symptomatic patients with
    internal carotid artery stenosis. (Updates
    previous guideline Neurology 199040682)
  • Additional clinical scenarios, such as use of CE
    combined with cardiac surgery (CABG), are also
    reviewed.

3
Introduction
  • Depending on the population, extracranial
    internal carotid artery (ICA) stenosis accounts
    for 15-20 of ischemic strokes.
  • CE is the most frequently performed operation to
    prevent stroke.
  • Since 1990 guideline, several multi-center trials
    have been completed. This statement reflects an
    update on major developments.

4
Methods
  • Vascular neurologists were appointed by the
    Therapeutics and Technology Assessment
    Subcommittee (TTA) of the AAN.
  • Nine clinical questions were identified and
    selected due to clinical importance.
  • A systematic search was performed for articles
    from 1990-2001.
  • Additional articles from 2002-2004 were included
    using pre-specified criteria.

5
Methods
  • Case reports, review articles, technical studies,
    and single surgeon case series were excluded.
  • After exclusions, total of 186 articles were
    reviewed independently by 2 committee members.
  • Number needed to treat (NNT) and number needed to
    harm (NNH) were evaluated in studies.
  • Recommendations generated based on application of
    levels of evidence to the abstracted articles
    using AAN schemes.

6
AAN Strength of Evidence
7
AAN Strength of Evidence
8
Translation of Evidence to Recommendation Level
9
Translation of Evidence to Recommendation Level
10
Clinical Question
  • Does CE benefit symptomatic and asymptomatic
    patients?

11
Analysis of the EvidenceSymptomatic patients
12
Analysis of the EvidenceSymptomatic patients
13
Analysis of the EvidenceSymptomatic patients
14
Clinical Question
  • Does CE benefit asymptomatic patients?

15
Analysis of the Evidence Asymptomatic patients
  • 3 Class I studies are available
  • Asymptomatic Carotid Atherosclerosis Study
    (ACAS), Veterans Affairs Study, Asymptomatic
    Carotid Surgery Trial (ACST)
  • 2 other studies were completed or planned but
    were stopped prematurely or had a suboptimal
    study design
  • Mayo Clinic trial stopped due to a high rate of
    MI (22) in the surgical group, CASANOVA

16
Analysis of the Evidence Asymptomatic patients
  • The Veterans Affairs study
  • 444 men with angiographically-proven 50-99
    asymptomatic stenosis
  • Nonsignficant trend favoring CE for prevention of
    ipsilateral stroke (9.4 vs. 4.7 at 4 years)
  • Primary endpoint transient ischemic attack
    (TIA)
  • The 30 day perioperative stroke and death rate
    was 4.7, NNH 21

17
Analysis of the EvidenceAsymptomatic patients
  • Asymptomatic Carotid Atherosclerosis Study (ACAS)
  • 1662 patients, 60-99 stenosis angiographically-pr
    oven for the surgical group primarily-proven with
    ultrasound for the medical group
  • Enrollment 1993-2003 with planned10 year
    follow-up
  • Eligibility carotid artery diameter reduction
    of at least 60,no symptoms within the past six
    months
  • Patients were randomized to best medical TX (BMT)
    or BMT CE

18
Analysis of the EvidenceAsymptomatic patients
  • Asymptomatic Carotid Atherosclerosis Study (ACAS)
  • Study stopped after 2.7 years median follow-up
    5.9 ARR at 5 years favoring CE (NNT 17)
  • 5 year projected rate of ipsilateral stroke
  • medically treated patients 11.0
  • surgically treated patients 5.1
  • relative risk reduction 53
  • 5 year projected rate for major ipsilateral
    stroke any perioperative major ipsilateral stroke
  • medically treated patients 6.0
  • surgical patients 3.4

19
Analysis of the EvidenceAsymptomatic patients
  • Asymptomatic Carotid Atherosclerosis Study (ACAS)
  • The perioperative stroke rate 2.3, NNH43
  • Such a low perioperative stroke/death rate has
    not been achieved in most recent observational
    studies or in the Aspirin and Carotid
    Endarterectomy (ACE) trial (n1512, stroke and
    death 4.6)

20
Analysis of the EvidenceAsymptomatic patients
  • Asymptomatic Carotid Surgery Trial (ACST)
  • Randomized study of immediate vs. indefinite
    deferral of CE
  • 5 five year follow-up at 126 centers in 30
    countries
  • diameter reduction stenosis by carotid
    ultrasound
  • Eligibility carotid artery diameter reduction
    of at least 60 on ultrasound and no symptoms
    within the past six months
  • Enrollment 1993 2003 planned 10 year follow-up
  • 3120 randomized patients - 2 groups of 1560 each

21
Analysis of the EvidenceAsymptomatic patients
  • Asymptomatic Carotid Surgery Trial (ACST)
  • Perioperative events (stroke and death within 30
    days) and the non-perioperative strokes combined
  • Net 5 year risks were 6.4 (immediate CE) versus
    11.8 (deferred CE) for all strokes 3.5 vs.
    6.1 for fatal or disabling strokes
  • Gain mostly in non-perioperative carotid
    territory ischemic strokes
  • The benefit was seen in both contralateral and
    ipsilateral carotid-territory strokes

22
Analysis of the EvidenceAsymptomatic patients
  • Asymptomatic Carotid Surgery Trial (ACST)
  • Subgroup analyses showed
  • benefits were significant for those lt 65 years,
    those between 65 and 74 years, but uncertain for
    those gt 75 years
  • Men and women both benefited but there were only
    a total of 40 non-perioperative strokes in women
    so the results were not as definite (p0.02)
  • 5 year benefit of CE appeared to be as great for
    those with lt80 diameter reduction (mean 69
    stenosis) as for those with 80-99 (mean 87)
    reduction
  • No significant difference in results in those
    patients who were never symptomatic compared to
    those with symptoms gt six months previously (7.1
    and 4.6 absolute five year gain, respectively)

23
Clinical Question
  • Is emergent CE beneficial in patients with
    progressing stroke of lt24 hours?

24
Analysis of the EvidenceEmergent CE
  • Four Class IV studies met the criteria
  • In 3 studies, neurological improvement was noted
    in 81-93 of patients who underwent emergent CE
  • Studies were fairly small in size, lacked
    objective evaluation of the reported neurological
    outcomes, and one study was clouded by coexisting
    treatments including emergent thrombolysis

25
Clinical Question
  • What are the most important clinical variables
    that impact the risk/benefit ratio?

26
Analysis of the EvidenceClinical Variables
  • None of the trials had clinical variables that
    impact risk/benefit as predetermined endpoints
  • In post-hoc analyses 2 variables stand out
    gender and nature of the presenting symptoms
  • In NASCET 50-69 stenosis group ACAS no benefit
    shown for CE in women
  • NASCET showed lower subsequent stroke risk in
    patients w/ retinal ischemia compared to patients
    with hemispheric events
  • A pooled analysis of the 3 symptomatic studies
    identified modifiers of CE benefit. Greatest
    benefit in men, patients above age 75 years, and
    those randomized within 2 weeks of their last
    symptomatic event

27
Clinical Question
  • What are the most important radiologic factors
    that impact the risk/benefit ratio?

28
Analysis of the EvidenceRadiologic Factors
  • Several studies addressed issues (status of the
    contralateral carotid artery, angiographic
    appearance of the ICA, and other factors).
  • NASCET and ACAS studies had highest level data on
    contralateral occlusion.
  • For symptomatic patients
  • Contralateral occlusion present surgical
    complication rate is higher than if the
    contralateral ICA is patent
  • Better outcome compared to medical management for
    patients with 70-99 stenosis
  • For asymptomatic patients
  • Contralateral occlusion present randomized
    evidence suggests that patients do slightly
    better with medical management (2.0 absolute
    increase in risk with CE at 5 years)

29
Analysis of the EvidenceRadiologic Factors
  • For patients with angiographic near-occlusion
  • Pooled analysis of the symptomatic studies
    suggests
  • CE is associated with trend toward benefit at 2
    years but no clear benefit at 5 years
  • BMT severe stenosis patients in NASCET-including
    those with near-occlusion-were offered CE after
    the 2 year results made available
  • Only Class IV evidence or below available for
    other factors such as influence of carotid siphon
    stenosis or posterior circulation stenosis.

30
Clinical Question
  • What is the ideal dose of aspirin preoperatively
    in patients undergoing CE?

31
Analysis of the EvidenceAspirin therapy
  • Aspirin and Carotid Endarterectomy trial (ACE)
  • 2,849 subjects, double-blind randomized clinical
    trial
  • Compared aspirin before carotid endarterectomy
    continued for 3 months at doses 81 mg, 325 mg,
    650 mg and 1300 mg
  • Primary outcome combined rate of stroke,
    myocardial infarction, and death was the
  • Outcome lower in the low-dose groups (81 mg and
    325 mg) than in the high-dose groups (650 mg and
    1300 mg) at 30 days and 3 months

32
Analysis of the EvidenceAspirin therapy
  • Another trial enrolled 232 subjects to 75mg
    aspirin or placebo before CE and continued for 6
    months.
  • Aspirin compared with placebo Trial demonstrated
    fewer strokes without recovery in those subjects
    randomized aspirin at 1 month and 6 months

33
Clinical Question
  • What are the data regarding CE concurrent with or
    prior to CABG?

34
Analysis of the EvidenceCABG
  • 48 studies for review, nine met criteria for
    inclusion (50 subjects).
  • No randomized clinical trials addressing this
    question the best available evidence comes from
    retrospective case control (class III) and case
    series (class IV) reports.
  • Some studies compared findings between groups
    with different surgical strategies, but because
    prospective criteria were not applied, a
    selection bias is likely.

35
Analysis of the EvidenceCABG
36
Analysis of the EvidenceCABG
37
Clinical Question
  • How long should one wait after a stroke to
    perform CE?

38
Analysis of the EvidenceTime to CE surgery
  • 6 retrospective cohort studies comparing timing
    of CE in patients after a stroke. Significant
    limitations in the designs of these studies.
  • 4 of the studies defined early surgery as lt 6
    weeks from the stroke.
  • 2 studies defined early surgery as lt four weeks
    from the stroke.
  • None of the studies found differences in the
    outcomes in terms of operative morbidity and
    longer-term follow-up.

39
Recommendations
40
Recommendations
41
Recommendations
42
Recommendations
43
Recommendations
44
Recommendations
45
Recommendations for Future Research
  • Improve quality of data is needed
  • The setting of urgent CE in patients with
    progressing stroke
  • The appropriateness of CE in community settings
  • The management of coexisting carotid and coronary
    artery disease
  • The timing of CE in patients with recent stroke.
  • Data are needed on newer antiplatelet agents in
    the perioperative setting
  • Data are needed on how CE compares to less
    invasive, endovascular treatment with stenting in
    patients with symptomatic and asymptomatic
    carotid stenosis.

46
Recommendations for Future Research
  • Data are needed on the role of cerebral
    hemodynamics in risk stratification for patients
    with carotid stenosis.
  • Data are needed to examine indices of
    vasoreactivity and cerebral perfusion in future
    studies of patients with both symptomatic and
    asymptomatic carotid stenosis.
  • There is a paucity of data on stroke rates in
    patients with carotid stenosis who receive an
    aggressive treatment regimen with statins, newer
    antiplatelet agents, and targeted blood pressure
    lowering.

47
Disclaimer
  • This statement is provided as an educational
    service of the American Academy of Neurology. It
    is based on an assessment of current scientific
    and clinical information. It is not intended to
    include all possible proper methods of care for a
    particular neurological problem or all legitimate
    criteria for choosing to use a specific
    procedure. Neither is it intended to exclude any
    reasonable alternative methodologies. The AAN
    recognizes that specific patient care decisions
    are the prerogative of the patient and the
    physician caring for the patient, based on all of
    the circumstances involved.

48
Acknowledgments
  • The committee thanks Drs. Chung Hsu and David
    Lefkowitz as liaisons from the TTA Subcommittee,
    Alison Nakashima, Paul Hetland, Nancy King, and
    Wendy Edlund from the American Academy of
    Neurology for their superb assistance in
    coordinating the review, and Vicki Glasgow for
    assistance with the literature search.

49
TTA Subcommittee Members
  • Therapeutics and Technology Assessment
    Subcommittee Members
  • Douglas S. Goodin, MD (Chair) Yuen T. So, MD,
    PhD (Vice-Chair) Carmel Armon, MD Richard M.
    Dubinsky, MD Mark Hallett, MD David Hammond,
    MD Cynthia Harden, MD Chung Hsu, MD, PhD
    (ex-officio) Andres M. Kanner, MD (ex-officio)
    David S. Lefkowitz, MD Janis Miyasaki, MD
    Michael A. Sloan, MD James C. Stevens, MD

50
To view the entire guideline and additional AAN
guidelines visit www.aan.com/professionals/prac
tice/index/cfm
  • Published in Neurology 200565794-801
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