Neurology -- Correspondence for Evans and Wijdicks, 57 (7) 1328-1330

Correspondence published:

Reply to Dr. Ballotta's letter: Bruce A Evans, Eelco F M Wijdicks (18 December 2001)

High-grade carotid stenosis detected before general surgery: Is endarterectomy indicated?: Enzo Ballotta (18 December 2001)

Reply to Dr. Ballotta's letter 18 December 2001

Bruce A Evans
Mayo Clinic Rochester, MN,
Eelco F M Wijdicks
Send Correspondence to journal:
Re: Reply to Dr. Ballotta's letter

bevans{at}mayo.edu Bruce A Evans, et al.

We thank Dr. Ballotta for his comments. True, our study [1], when set against large trials, is small, observational, and retrospective. Nevertheless, it represents the first clear attempt to address this important clinical dilemma. A prospective study would be welcomed. But we do think our data shows there is no imperative for routine carotid endarterectomy in patients with asymptomatic carotid lesions detected prior to a planned general surgical procedure.
We should clarify that with regard to “preoperative symptoms”, all of our patients, by selection, had asymptomatic carotid stenosis. Among other risk factors for perioperative stroke, we found that patients with a previous history of TIA or stroke did not have a higher perioperative risk. Those previous ischemic events were in all instances either remote, unrelated to the demonstrated carotid artery stenosis, or both. In fact in our practice a patient with recent symptoms referable to a high-grade carotid stenosis would have had an endarterectomy prior to any elective surgery. All such patients were excluded.
Our finding that in a group selected for the presence of stenosis one half of the perioperative strokes occurred ipsilateral to a severe carotid stenosis is unsurprising. Since the perioperative stroke rate in that group was not significantly different from the overall group or any subgroup, it does not follow that endarterectomy in all of these patients would have been beneficial in terms of significantly reducing the combined perioperative stroke risk.
The fact that asymptomatic patients with greater than 60% stenoses have a modest reduction in ipsilateral stroke risk over 5 years does not imply that all subsequent ipsilateral perioperative strokes would be prevented or that the combined perioperative stroke risk would be lowered sufficiently enough to justify the routine performance of prophylactic endarterectomy. We simply do not know why perioperative strokes after general surgery occur. We agree with Dr. Ballotta that a statistically more powerful study would help identify any subgroups of asymptomatic carotid stenosis patients that might benefit from prophylactic endarterectomy prior to an unrelated surgical procedure. This would need to be a carefully conducted prospective cohort in a randomized trial.
Reference:
1) Evans BA, Wijdicks EFM. High-grade carotid stenosis detected before generalsurgery: Is endarterectomy indicated? Neurology 2001;57:1328-1330.

High-grade carotid stenosis detected before general surgery: Is endarterectomy indicated? 18 December 2001

Enzo Ballotta
University of Padula School of Medicine Padova Italy
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Re: High-grade carotid stenosis detected before general surgery: Is endarterectomy indicated?

enzo.ballotta{at}unipd.it Enzo Ballotta

Evans and Wijdicks [1] recently reported that internal carotid artery (ICA) stenosis carried a perioperative stroke risk of approximately 3.6% in a series of 284 unselected patients undergoing general anesthesia and non-cardiac, non-carotid surgery. For prophylactic carotid endarterectomy (CEA) to be recommendable in patients with known ICA stenosis, they suggested that the global perioperative risk of CEA plus the general surgical procedure would need to be significantly lower than 3.6%. Although this risk was higher than in unselected population, they concluded that it was not sufficient to prompt prophylactic CEA. This conclusion is correctly based on the crude sum of the percentages emerging from the study, but could be misleading.
First, caution is needed in drawing conclusions for clinical management from small series, such as the one reported by Evans and Wijdicks [1], which included ten cases observed over 10 years. Small numbers prevented any stratification of the risk according to ICA stenosis severity and had no significant power for meaningful analysis.
Second, we unfortunately have no information on the relationship between preoperative neurologic symptoms, degree of ICA stenosis and perioperative stroke in this series. Without this information, it is impossible to say whether CEA would be useful in a given patient.
Further, although 36% (102/284) of patients in this setting of unrelated surgery had preoperative neurologic symptoms, the authors’ conclusions are drawn as if all perioperative neurologic events had occurred in asymptomatic patients.
However, if we exclude perioperative strokes ipsilateral to an occluded ICA and strokes occurring in patients with an apparently normal ICA, half of the perioperative strokes (5/10) occurred in patients with anatomically severe ICA stenosis that would have benefited from CEA. Since there is compelling evidence of perioperative strokes being related to severe, previously-asymptomatic ipsilateral ICA lesions, an important finding of the Evans and Wijdicks study [1] is that patients with severe ICA lesions represent a subgroup of patients at special risk of increased neurologic morbidity when undergoing unrelated surgery.
A positive correlation between stroke risk and increasing degrees of stenosis was also found in asymptomatic patients in the European Carotid Surgery Trial [2], and a similar finding was reported by the North American Symptomatic Carotid Endarterectomy Trial (NASCET) investigators [3] in a subgroup analysis of asymptomatic stenoses contralateral to symptomatic lesions in patients enrolled in the NASCET. So why not recommend considering prophylactic CEA in asymptomatic patients with severe ICA stenosis before any unrelated elective surgery?
REFERENCES:
1) EVANS BA, WIJDICKS EFM. High-grade carotid stenosis detected before general surgery: Is endarterectomy indicated? NEUROLOGY 2001;57:1328-1330.
2) European Carotid Surgery Trialists Collaborative Group. Risk of stroke in the distribution of an asymptomatic carotid artery. LANCET 1995;345, 209-212.
3) INZITARI D, ELIASZIW M, GATES P et al. The causes and risk of stroke in patients with asymptomatic internal carotid artery stenosis. N ENGL J MED 2000;342:1693-1700.