assessment: carotid endarterectomy ― an evidence-based review

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© 2005 American Academy of Neurology February 25, 2004 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 2005;65:794-801

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Page 1: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Assessment: Carotid Endarterectomy―

An Evidence-Based ReviewReport 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 2005;65:794-801

Page 2: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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 1990;40:682)

Page 3: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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.

Page 4: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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.

Page 5: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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.

Page 6: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

AAN Strength of Evidence

Class I Class II

Evidence provided by a prospective study in a broad spectrum of persons with the suspected condition, using a “gold standard” for case definition, where test is applied in a blinded evaluation, and enabling the assessment of appropriate tests of diagnostic accuracy. In addition, there must be adequate accounting for drop-outs with numbers sufficiently low to have minimal potential for bias

Evidence provided by a prospective study of a narrow spectrum of persons with the suspected condition, or a well designed retrospective study of a broad spectrum of persons with an established condition (by “gold standard”) compared to a broad spectrum of controls, where test is applied in a blinded evaluation, and enabling the assessment of appropriate tests of diagnostic accuracy

Page 7: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

AAN Strength of Evidence

Class III Class IV

Evidence provided by a retrospective study where either persons with the established condition or controls are of a narrow spectrum, and where test is applied in a blinded evaluation.

Any design where test is not applied in blinded evaluation OR evidence provided by expert opinion alone or in descriptive case series (without controls).

Page 8: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Translation of Evidence to Recommendation Level

Level A Level B

Level A = Established as useful/predictive or not useful/predictive for the given condition in the specified population

Level A rating requires at least one convincing class I study or at least two consistent, convincing class II studies

Level B = Probably useful/predictive or not useful/predictive for the given condition in the specified population

Level B rating requires at least one convincing class II study or at least three consistent class III studies

Page 9: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Translation of Evidence to Recommendation Level

Level C Level U

Level C = Possibly useful/predictive or not useful/predictive for the given condition in the specified population

Level C rating requires at least two convincing and consistent class III studies

Level U = Data inadequate or conflicting. Given current knowledge, test/predictor is unproven

Page 10: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Clinical Question

Does CE benefit symptomatic and asymptomatic patients?

Page 11: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Analysis of the EvidenceSymptomatic patients

Author/ Year Ipsilateral Stroke risk plus periop stroke & death

Periop stroke & death

Periop disabling stroke & death

Any stroke

Major stroke or death

NASCET Collab. 1991

Stenosis=

70-99%

CE + BMT=9%

BMT=26%

5.8%

3.3%

2.7%

0.9%

12.6

27.6

8.0%

18.1%

ECST Collab. Group 1991

Stenosis=

70-99%

CE+BMT=9.5%

BMT = 13.6%

7.5%

NA

3.7%

NA

NA

NA

4.8%

8.4%

BMT = best medical therapy

Page 12: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Author/ Year Ipsilateral Stroke risk plus periop stroke & death

Periop stroke & death

Periop disabling stroke & death

Any stroke

Major stroke or death

Mayberg 1991

Stenosis=

50-99%

CE + BMT=4.4%

BMT=7.1%

6.5%

2.2%

4.4%

0%

NA

NA

NA

NA

ECST Collab. Group 1996

Stenosis=

50-69%

CE + BMT=NA

BMT=NA

NA

NA

7.9% 16.8%

14.2%

NA

NA

NASCET collab.1998

Stenosis=

50-69%

CE + BMT=1.9%

BMT=7.0%

22.2%

15.7%

NA

NA

19.8%

26.4%

14.9%

20.1%

Analysis of the EvidenceSymptomatic patients

Page 13: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Author/ Year Ipsilateral Stroke risk plus periop stroke & death

Periop stroke & death

Periop disabling stroke & death

Any stroke

Major stroke or death

ECST Collab. Group 1996

Stenosis=

30-49%

CE + BMT=NA

BMT=NA

NA

NA

8.0%

NA

16.2% 10.4%

NA

NA

ECST Collab. Group 1991, 1998

Stenosis=

0-29%

CE+BMT=11.3% BMT=5.6%

3.3%

0

1.7%

0 %

17.1%12.8%

36.7%30.7%

Rothwell 2003 Stenosis=

<50%

CE+BMT=NA BMT=NA

6.7%

NA

NA

NA

NA

NA

NA

NA

Analysis of the EvidenceSymptomatic patients

Page 14: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Clinical Question

Does CE benefit asymptomatic patients?

Page 15: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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

Page 16: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Analysis of the EvidenceAsymptomatic patients

• Asymptomatic Carotid Atherosclerosis Study (ACAS) – 1662 patients, 60-99% stenosis angiographically-

proven 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

Page 17: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Analysis of the EvidenceAsymptomatic patients

• Asymptomatic Carotid Atherosclerosis Study (ACAS)

– 5 year projected rate of ipsilateral stroke • medically treated patients 11.0% • surgically treated patients 5.1% • relative risk reduction 53%

Page 18: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Clinical Question

Is emergent CE beneficial in patients with progressing stroke of <24 hours?

Page 19: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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

Page 20: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Clinical Question

What are the most important clinical variables that impact the risk/benefit ratio?

Page 21: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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

Page 22: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Clinical Question

What are the most important radiologic factors that impact the risk/benefit ratio?

Page 23: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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)

Page 24: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Clinical Question

What is the ideal dose of aspirin preoperatively in patients undergoing CE?

Page 25: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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

Page 26: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Clinical Question

How long should one wait after a stroke to perform CE?

Page 27: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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 < 6 weeks from the stroke.

• 2 studies defined early surgery as < four weeks from the stroke.

• None of the studies found differences in the outcomes in terms of operative morbidity and longer-term follow-up.

Page 28: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

RecommendationsUse of Carotid Endarterectomy in Symptomatic Patients

Stenosis (%) Recommendation

70-99% CE is established as effective for recently symptomatic (within previous 6 months) patients with 70-99% ICA angiographic stenosis (Level A).

50-69%

•CE may be considered for patients with 50-69% symptomatic stenosis (Level B) but the clinician should consider additional clinical and angiographic variables (Level C). See tables below.

•It is recommended that the patient have at least a five year life expectancy and that the peri-operative stroke/death rate should be <6% for symptomatic patients (Level A).

<50% •CE should not be considered for symptomatic patients with <50% stenosis (Level A).•Medical management is preferred to CE for symptomatic patients with <50% stenosis (Level A).

Page 29: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Recommendations

Use of Carotid Endarterectomy in Asymptomatic Patients

Stenosis (%)

Recommendation

60-99%

It is reasonable to consider CE for patients between the ages of 40-75 years and with asymptomatic stenosis of 60-99% if the patient has an expected five year life expectancy and if the surgical stroke or death frequency can be reliably documented to be <3% (Level A). The five year life expectancy is important since peri-operative strokes pose an up front risk to the patient and the benefit from CE emerges only after a number of years.

Page 30: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Recommendations

Patient Variables to Consider in Carotid Endarterectomy Decision-making

Patient

variables

Recommendation

Symptomatic women

Women with 50-69% symptomatic stenosis did not show clear benefit in previous trials (Level C).

Patients w/ hemispheric TIA or stroke

•Patients with hemispheric TIA or stroke had greater benefit from CE than patients with retinal ischemic events (Level C).

Progressing neurological deficit

•No recommendation can be provided regarding the value of emergent CE in patients with a progressing neurological deficit (Level U).

Page 31: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Recommendations

Radiologic Factors to Consider in Carotid Endarterectomy

Decision-making

Radiologic Factors Recommendation

Contralateral occlusion in symptomatic patients

Contralateral occlusion is associated with increased operative risk but persistent benefit (Level C).

Contralateral occlusion in asymptomatic patients

Contralateral occlusion erases the small benefit of CE in asymptomatic patients (Level C).

Page 32: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Recommendations

Reviewed Clinical Scenarios

Peri-operative aspirin

• Symptomatic and asymptomatic patients undergoing CE should be given aspirin (81 or 325 mg/day) prior to surgery and for at least 3-months following surgery to reduce the combined endpoint of stroke, myocardial infarction, and death (Level A). Although data are not available, it is recommended that aspirin (81 or 325 mg/day) be continued indefinitely provided that contraindications are absent. Aspirin at 650 or 1300 mg/day is less effective in the peri-operative period.

• The data are insufficient to recommend the use of other anti-platelet agents in the peri-operative setting.

Page 33: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

Recommendations

Reviewed Clinical Scenarios

Recent TIA or non-disabling stroke

• For patients with severe stenosis and a recent TIA or nondisabling stroke, CE should be performed without delay, preferably within two weeks of the patient’s last symptomatic event (Level C).

• There is insufficient evidence to support or refute the performance of CE within four to six weeks of a recent moderate to severe stroke (Level U).

CE prior to or concurrent with CABG

At this time the available data are insufficient to declare either CE before or simultaneous with CABG as superior in patients with concomitant carotid and coronary artery occlusive disease (Level U).

Page 34: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

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

Page 35: Assessment: Carotid Endarterectomy ― An Evidence-Based Review

© 2005 American Academy of Neurology February 25, 2004

COMMENTTHANK YOU

Published in Neurology 2005;65:794-801