Published online before print June 26, 2003, doi: 10.1161/01.STR.0000079175.59874.62
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(Stroke. 2003;34:1816.)
© 2003 American Heart Association, Inc.
Controversies in Stroke |
For Severe Carotid Stenosis Found on Ultrasound, Further Arterial Evaluation Is Unnecessary
From the Division of Vascular Surgery, UCLA Center for the Health Sciences, Los Angeles, Calif.
Correspondence to Wesley S. Moore, MD, Division of Vascular Surgery, UCLA Center for the Health Sciences, Box 956904, Los Angeles, CA 90095-6904. E-mail wmoore{at}mednet.ucla.edu
Key Words: angiography • carotid endarterectomy • carotid stenosis
The objective of performing carotid endarterectomy (CEA) is to reduce the risk of stroke. CEA can be justified only if the stroke morbidity and mortality from operation is significantly less than with alternative methods of management. Complications associated with preoperative invasive diagnostic procedures must be counted against the risk of operation because the invasive diagnosis would likely not be performed if surgery were not contemplated.
Intra-arterial contrast angiography carries several risks including the risk of stroke and death. These risks are increased in patients with severe cerebrovascular occlusive disease as opposed to the risk in patients with indications for angiography other than carotid bifurcation disease.
The benefits of carotid endarterectomy become more compelling to the extent that morbidity and mortality related to all aspects of perioperative management can be reduced. Clinical investigation, experience, and surgeon competence have combined to bring the risk of operation close to an irreducible minimum. The opportunity to further reduce perioperative risk by eliminating the need for contrast angiography is perhaps the single best method to achieve a major risk reduction for patients selected to undergo carotid endarterectomy.
Risks of Angiography
The risk of minor stroke as a consequence of diagnostic angiography is reported to range from 1.3% to 4.5%, and the risk of major stroke from 0.6% to 1.3%.1–3 In the Asymptomatic Carotid Atherosclerosis Study (ACAS) trial, in which randomization occurred prior to angiography, all patients who were randomized to the surgical arm were required to undergo postrandomization angiography. That design provided the opportunity to assess the true audited risk of angiography as it took place in centers of excellence participating in the trial. The combined neurologic morbidity and mortality from angiography in asymptomatic patients with hemodynamically significant carotid stenosis was 1.2%.4 The risk of stroke morbidity and mortality from carotid endarterectomy itself was 1.52%. Therefore, had the operation been done on the basis of ultrasound alone, the risk of operation would have been cut almost in half and the comparative benefit of CEA versus medical management would have been even more compelling.
Angiography carries an even greater risk in symptomatic patients. Theodotou et al reported a 7.7% stroke morbidity and mortality in patients undergoing contrast angiography for stroke-in-evolution and a 12.5% risk inpatients who had bilateral severe carotid stenosis.5 Perhaps the risk of angiography could be justified if the findings contributed to important clinical decisions or to surgical management, but it rarely does. Akers et al reviewed their experience with 1000 aortocranial angiograms and noted that only 6 patients were found to have significant lesions of the aortic arch trunks.6 Furthermore, tandem intracranial lesions in the distribution of the carotid artery, exceeding a 75% stenosis, are also rare.
Angiography of the cerebral circulation is often referred to as a "gold standard." Unfortunately, this is also a misconception. The real gold standard for carotid bifurcation disease is the explanted atherosclerotic specimen. When the results of duplex sonography and carotid angiography are compared with the explanted lesion, rather than with each other, duplex sonography is actually found to be more accurate than carotid angiography.6–9 Because carotid angiography is a 2-dimensional study of a plaque that often has eccentric configuration, it is almost inevitable that the angiogram underestimates the percent stenosis.
There has been an increasing experience with CEA on the basis of sonography alone. Reports of this experience document both safety and accuracy of the technique while avoiding the risk and expense of routine angiography.10
Suffice it to say that the willingness to accept duplex ultrasound as the definitive preoperative test is based on the reliability of the ultrasound laboratory in which the test is performed. Given that the duplex ultrasound examination is both technician- and machine-dependent, the laboratory performing the test must be able to show that it has validated its testing procedures. In the United States, the Intersocietal Commission for Accreditation of Vascular Laboratories (ICAVL) has established validation criteria, and laboratories that are certified by ICAVL can be regarded as providing data with the highest standards of accuracy. On the basis of these arguments, I can comfortably state that, with rare exception, patients with severe carotid stenosis as documented by duplex ultrasound do not require invasive angiography prior to carotid endarterectomy.
Footnotes
Section Editors: Geoffry A. Donnam, MD, FRACP and Stephen M. Davis, MD, FRACP
The opinions expressed in this editorial are not necessarily those of the editors or of the American Stroke Association.
References
1. Hankey GJ, Warlow CP, Sellar RJ. Cerebral angiographic risk in mild cerebrovascular disease. Stroke. 1990; 21: 209–222.
2. Dion JE, Gates PC, Fox AJ, Barnett HJM, Blom RJ. Clinical events following neuroangiography: a prospective study. Stroke. 1987; 18: 997–1004.
3. Davies KN, Humphrey PR. Complications of cerebral angiography in patients with symptomatic carotid territory ischaemia screened by carotid ultrasound. J Neurol Neurosurg Psychiatry. 1993; 56: 967–972.
4. Executive Committee for the Asymptomatic Carotid Atherosclerosis (ACAS) Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA. 1995; 273: 1421–1428.
5. Theodotou BC, Whaley R, Mahaley MS. Complications following transfemoral cerebral angiography for cerebral ischemia: report of 159 angiograms and correlation with surgical risk. Surg Neurol. 1987; 28: 90–92.[CrossRef][Medline] [Order article via Infotrieve]
6. Akers DL, Markowitz IA, Kerstein MD, et al. The value of aortic arch study in evaluation of cerebrovascular insufficiency. Am J Surg. 1987; 154: 220–223.[CrossRef][Medline] [Order article via Infotrieve]
7. O’Donnell TF Jr, Erdoes L, Mackey WC, et al. Correlation of B-mode ultrasound imaging and arteriography with the pathologic findings of carotid endarterectomy. Arch Surg. 1985; 120: 443–449.
8. Goodson SF, Flanigan DP, Bishara RA, et al. Can carotid duplex scanning supplant arteriography in patients with focal carotid territory symptoms? J Vasc Surg. 1987; 5: 551–557.[CrossRef][Medline] [Order article via Infotrieve]
9. Fontenelle LJ, Simber SC, Hanson TL. Carotid duplex scan versus angiography in the evaluation of carotid artery disease. Am Surg. 1994; 60: 864–868.[Medline] [Order article via Infotrieve]
10. Chervu A, Moore WS. Carotid endarterectomy without arteriography: personal series and review of the literature. Ann Vasc Surg. 1994; 8: 296–302.[CrossRef][Medline] [Order article via Infotrieve]
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