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(Stroke. 1998;29:1475-1476.)
© 1998 American Heart Association, Inc.

Letters to the Editor

Concerns Regarding Carotid Endarterectomy Guidelines

Seemant Chaturvedi, MD

Department of Neurology, Wayne State University, Detroit, Michigan

Alison Halliday, MD

Department of Surgery, St. Mary's Hospital, London, UK

To the Editor:

We were surprised to read the rather unequivocal endorsement¹ by the American Heart Association writing group of carotid endarterectomy (CE) for asymptomatic stenosis of greater than 60%. This position does not represent the viewpoint of all stroke neurologists or surgeons, and some professional groups have recently come to the exact opposite conclusion, not recommending CE for asymptomatic stenosis.²

The writing group states that CE is beneficial if the surgical complication rate is less than 3%. Current evidence indicates that CE complication rates are not being closely monitored at US hospitals.³ A recent study found that the surgical complication rates were either unknown or not being monitored at over 50% of teaching hospitals in the United States.⁴ In the "real world" of CE practice, it is unlikely that a complication rate this low can be uniformly achieved, and a 1991 analysis of Medicare data found that the death rate associated with CE was 2.3%.⁵

In addition, we and others have concerns that the Asymptomatic Carotid Atherosclerosis Study (ACAS) results cannot be generalized.^{6 7 8 9} Only 4% of the eligible patients were entered into the study.¹⁰ In addition, 29% of the surgeons who applied for participation in the trial were either rejected or did not complete the credentialing process.¹¹ Thus, in the ideal setting for producing a positive surgical result (namely, combining low-surgical-risk patients with surgeons vetted for their excellence), a statistically significant result was obtained, which may not be clinically meaningful to all clinicians.

Finally, for full disclosure, it would be of interest to know how many members of the writing group were actual ACAS participants. This may affect the panel's objectivity, and we would suggest that when controversial studies are involved, future writing groups should include a balance between study participants and nonparticipants.

References

1. Biller J, Feinberg WM, Castaldo JE, Whittemore AD, Harbaugh RE, Dempsey RJ, Caplan LR, Kresowik TF, Matchar DB, Toole JF, Easton JD, Adams HP Jr, Brass LM, Hobson RW II, Brott TG, Sternau L. Guidelines for carotid endarterectomy: a statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. Stroke.. 1998;29:554–562.[Free Full Text]

2. Perry JR, Szalai JP, Norris JW, for the Canadian Stroke Consortium. Consensus against both endarterectomy and routine screening for asymptomatic carotid artery stenosis. Arch Neurol.. 1997;54:25–28.[Abstract/Free Full Text]

3. Goldstein LB, Moore WS, Robertson JT, Chaturvedi S. Complication rates for carotid endarterectomy: a call to action. Stroke.. 1997;28:889–890.[Free Full Text]

4. Chaturvedi S, Femino L. Are carotid endarterectomy complication rates being monitored? Neurology. In press.

5. Dyken ML. Controversies in stroke: past and present. Stroke.. 1993;24:1251–1258.[Free Full Text]

6. Barnett HJM, Eliasziw M, Meldrum HE, Taylor DW. Do the facts and figures warrant a 10-fold increase in the performance of carotid endarterectomy on asymptomatic patients? Neurology.. 1996;46:603–608.[Free Full Text]

7. Warlow C. Endarterectomy for asymptomatic carotid stenosis? Lancet.. 1995;345:1254–1255.[Medline] [Order article via Infotrieve]

8. Hennerici M, Drafferttstrofer M, Meairs S. Concerns about generalisation of premature ACAS recommendations for carotid endarterectomy. Lancet.. 1995;345:1041. Letter.

9. Chaturvedi S, Halliday A. Is another clinical trial warranted regarding endarterectomy for asymptomatic carotid stenosis? Cerebrovasc Dis. In press.

10. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA.. 1995;273:1421–1428.[Abstract/Free Full Text]

11. Moore WS, Vescera CL, Robertson JT, Baker WH, Howard VJ, Toole JF. Selection process for surgeons in the Asymptomatic Carotid Atherosclerosis Study. Stroke.. 1991;22:1353–1357.[Abstract/Free Full Text]

Response

José Biller, MD

Department of Neurology, Indiana University School of Medicine

John E. Castaldo, MD

Division of Neurology, Penn State at Hershey

Anthony D. Whittemore, MD

Department of Surgery, Harvard Medical School

Robert E. Harbaugh, MD

Section of Neurosurgery, Dartmouth-Hitchcock Medical Center

Robert J. Dempsey, MD

Department of Neurosurgery, University of Wisconsin Medical Center

Louis R. Caplan, MD

Department of Neurology, New England Medical Center

Timothy F. Kresowik, MD

Department of Surgery, University of Iowa Hospitals and Clinics

David B. Matchar, MD

Center for Clinical Health Policy, Duke University

James F. Toole, MD

Department of Neurology, Bowman Gray School of Medicine

J. Donald Easton, MD

Department of Neurology, Brown University

Harold P. Adams, Jr, MD

Department of Neurology, University of Iowa Hospitals

Lawrence M. Brass, MD

Department of Neurology, Yale University School of Medicine

Robert W. Hobson, II, MD

Department of Surgery, University of Medicine and Dentistry of New Jersey, New Jersey Medical School

Thomas G. Brott, MD

Department of Neurology, University of Cincinnati College of Medicine

Linda Sternau, MD

Department of Neurosurgery, Mt Sinai Medical Center, Miami Beach, Florida

I believe that every member of the writing committee was and is intimately familiar with all of the arguments advanced by both the ACAS supporters and the ACAS detractors. Nevertheless, the ACAS study is level I evidence (grade A recommendation) that documented a statistically significant benefit of CEA for stroke prevention in patients with 60% diameter reduction asymptomatic carotid stenosis. We can argue forever about the clinical significance of this finding, but it does not change the conclusions of the study. We did not use terms such as "so compelling" or "unequivocally," but rather outlined the rules of evidence used and presented that study as well as other studies in the context of those rules. As noted in the paragraph above the recommendation, " ... some investigators consider it acceptable to delay surgery until there is >80% carotid stenosis ..." we assume that Drs Chaturvedi and Halliday and many other distinguished and respected colleagues fall into that category. In short, we believe the statement in the AHA guidelines is evidence based and perfectly reasonable.

The writing group was composed of a well-balanced panel of recognized experts in carotid artery disease from the disciplines of neurology, vascular surgery, and neurosurgery. Parenthetically, we believe the composition of the writing group is irrelevant if an evidence-based approach to guidelines development is used. That is the value of such methodology.

The relative clinical benefits of CEA for severe and moderate symptomatic stenosis and asymptomatic stenosis are well known. The data alone do not help us decide where to draw the line that divides a "worthwhile" procedure from one that is "not indicated" from a cost-to-benefit analysis viewpoint. We believe that kind of decision requires economic, social, ethical, and political analysis, and it was considered beyond the scope of this guidelines paper.

We do not recommend the blanket use of carotid endarterectomy in asymptomatic populations of patients in our AHA report. We simply endorse surgery on asymptomatic patients with 60% diameter stenosis by a surgeon who does surgery with <3% risk. We cannot be held responsible for people who misapply guidelines, whether it be this set of guidelines or any other set of guidelines.

The statement that only 4% of eligible patients were entered in the study is not true. The JAMA article states that 42 000 patients were screened and 1662 patients randomized.¹ Screened means evaluated to determine eligibility. Study participants were screened from ultrasound vascular labs, and many patients were not eligible because of symptomatic status, degree of stenosis, or other reasons. Complete data on exclusion criteria were not provided in the manuscript.

In short, we think that the AHA CEA Guidelines are, by and large, evidence based and do not need to be amended. While investigators may respond to any scientific study with their own degree of questions, we think the facts on this speak very clearly for themselves, and we endorse that result unless otherwise equally careful studies suggest an alternative result.

References

1. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid stenosis. JAMA. 1995;273:1421–1428.

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