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Etiology

Review: Stroke and death from carotid endarterectomy are predicted by 5 clinical and 3 angiographic factors

ACP J Club. 1998 May-June;128:77. doi:10.7326/ACPJC-1998-128-3-077


Source Citation

Rothwell PM, Slattery J, Warlow CP. Clinical and angiographic predictors of stroke and death from carotid endarterectomy: systematic review. BMJ. 1997 Dec 13;315:1571-7.


Abstract

Objective

To determine, using meta-analysis, the risk factors for stroke and death after carotid endarterectomy.

Data sources

Studies were identified by searching MEDLINE (1980 to 1996) using the terms carotid endarterectomy and carotid surgery, the stroke database from the Cochrane Collaboration, and bibliographies of relevant studies.

Study selection

Prospective and retrospective studies were selected if they reported the number of strokes and deaths that occurred within 30 days of carotid endarterectomy, endarterectomy was done for stenosis but not for acute stroke, risks were defined per operation and not per patient if patients could have had bilateral endarterectomy, the risk of the operation was assessed before surgery, and no evidence was found of a systematic policy for patients with different characteristics to be operated on by different surgeons or at different institutions.

Data extraction

Data were extracted on occurrences of stroke and death and on 14 clinical and angiographic risk factors. Clinical factors were presenting symptoms; sex; age; presence of hypertension, diabetes mellitus, angina, recent myocardial infarction, and peripheral vascular disease; and smoking status. Angiographic factors were occlusion of contralateral internal carotid artery, ipsilateral plaque surface irregularity, and stenosis of distal ipsilateral internal or external carotid artery.

Main results

126 studies were identified, and 36 met the selection criteria. 1 of the 14 risk factors (monocular ischemic attack, P < 0.001) was associated with decreased incidence of stroke and death, and 7 factors (peripheral vascular disease, P < 0.001; occlusion of the contralateral internal carotid artery, P < 0.001; systolic blood pressure > 180 mm Hg, P < 0.001; stenosis of the ipsilateral external carotid artery, P = 0.03; stenosis of the distal ipsilateral internal carotid artery, P = 0.02; female sex, P < 0.005; and age ≥ 75 y, P < 0.01) were associated with increased incidence (Table).

Conclusions

The risk for stroke and death within 30 days of carotid endarterectomy is associated with 5 clinical factors and 3 angiographic factors. All factors but monocular transient ischemic attack increase risk.

Source of funding: No external funding.

For article reprint: Dr. P.M. Rothwell, Department of Clinical Neurology, Radcliffe Infirmary, Woodstock Road, Oxford OX2 6HE, England, UK. FAX 44-1865-790403.


Table. Relative odds of stroke and death within 30 days of carotid endarterectomy

Characteristics Number of studies Odds ratio 95% CI
Monocular vs cerebral transient ischemic attack 7 0.49 0.37 to 0.66
Peripheral vascular disease 1 2.19 1.40 to 3.60
Occlusion of contralateral internal carotid artery 14 1.91 1.35 to 2.69
Hypertension (systolic blood pressure > 180 mm Hg) 4 1.82 1.37 to 2.41
Stenosis of ipsilateral external carotid artery 1 1.61 1.05 to 2.47
Stenosis of distal ipsilateral internal carotid artery 5 1.56 1.03 to 2.36
Female sex 7 1.44 1.14 to 1.83
Age ≥ 75 years 10 1.36 1.09 to 1.71

Commentary

The number of carotid endarterectomies being done in many centers has increased greatly since the publication of a North American (1) and a European study (2) in 1991. However, vascular surgeons still report wide variations between centers and countries in the number of operations that are done per unit of population and in the indications for surgery, particularly in the proportion of asymptomatic patients treated. The study by Rothwell and colleagues is a very helpful attempt to bring together the available data on prediction of stroke and death after surgery. The variations in practice patterns must be remembered during evaluation of the data because they raise the issue of the effect of publication bias.

This review has strong evidence that cerebral transient ischemia rather than monocular symptoms, age ≥ 75 years, hypertension > 180 mm Hg systolic, female sex, occlusion of the contralateral internal carotid artery, and stenosis of the ipsilateral distal internal carotid artery are associated with greater risk for stroke and death. I reserve judgment on 2 factors, peripheral vascular disease and external carotid artery stenosis, because the conclusions about them are based on a single study.

Stratification of risk in patients being considered for carotid endarterectomy is important when informed consent from the patient is being obtained as well as when outcomes among surgeons and centers are being compared. Although this study is a valuable aid to the stratification process, the authors acknowledge that their conclusions need to be validated by larger sets of data, a statement with which I agree.

Irwin Faris, MD
University of MelbourneMelbourne, Victoria, Australia


References

1. North American Symptomatic Carotid Endarterectomy Trial Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med. 1991;325:445-53.

2. European Carotid Surgery Trialists' Collaborative Group. MRC European Carotid Surgery Trial: interim results for symptomatic patients with severe (70-99%) or with mild (0-29%) carotid stenosis. Lancet. 1991; 337:1235-43.