doi: 10.1161/01.STR.0000033481.56109.97
(Stroke. 2002;33:2347.)
© 2002 American Heart Association, Inc.
Letters to the Editor |
Patient Selection for Carotid Angioplasty and Stenting
Department of Neurosurgery, University Hospital of Berne, Berne, Switzerland
Department of Neurology, University Hospital of Zürich, Zürich, Switzerland
To the Editor:
We read with interest the article by Dietz et al1 recently published in Stroke. The authors report the clinical results of a consecutive series of 43 patients with symptomatic carotid stenosis treated by angioplasty and stenting. We would like to express concern about the selection of patients for endovascular treatment in this study.
In the title and within the article, the authors emphasize the selection of patients according to the prognostic model of Rothwell et al2 for carotid endarterectomy. This model was developed from data gathered in the European Carotid Surgery Trial3 (ECST) to identify the best candidates for surgical treatment as opposed to medical therapy alone. The model included 2 sets of prognostic factors for medical and surgical adverse events and provided a score from 0 to 5 that predicted benefit (
4), no significant benefit (>1 to <4), or potential harm (
1) of the operation. The conclusion drawn from Rothwell et al was to exclude patients with scores <4 from the operation and to treat them exclusively with prophylactic medical therapy.
The prognostic model was developed from data on patients with 0% to 69% carotid stenosis in the ECST and then tested and validated on 990 ECST patients with 70% to 99% carotid stenosis assigned to surgery (594) or medical therapy alone (396). To the best of our knowledge, the prognostic model has not yet been validated by institutions other than ECST Collaborative Group, especially not by single centers confronted with the selection of individual patients for carotid endarterectomy.
Our concern about the selection procedure chosen by Dietz et al to indicate endovascular treatment of carotid stenosis is that patients with a Rothwell score <4 have been excluded from surgery but not treated medically as would be requested by the model. In fact, based on a prognostic model that has not yet been validated by independent centers, these patients have been denied a therapy, carotid endarterectomy, whose safety is established, only to be exposed to a treatment, angioplasty and stenting, whose safety and efficacy are still in investigation. In our opinion, such a procedure is questionable.
From a scientific point of view, a statistical model developed for a certain treatment cannot automatically be used for another therapy. The 3 surgical risk factors elaborated by Rothwell et al to calculate their prognostic scores were derived from patients treated exclusively with open endarterectomy. They included female sex, peripheral vascular disease, and systolic blood pressure >180 mm Hg. Before the model can be extended to angioplasty and stenting, it has to be proved that these factors keep their prognostic value in patients treated with angioplasty and stenting.
From an ethical point of view, we disapprove of the exclusion of patients from the standard treatment to recruit them for a new therapeutic modality whose safety has not yet been compared with this standard treatment. This is acceptable only in the setting of a prospective randomized trial in which patients are informed about both therapeutic modalities and have the possibility to refuse the proposed new treatment. There are presently several trials running in Europe and the United States that compare both treatments prospectively.4 As long as reliable data on the results of these trials are not available, it is recommended to perform primary endovascular therapy of carotid stenosis only in the frame of study protocols. In the study by Dietz et al, patients gave written consent to angioplasty and stenting, but it is not stated whether they were informed about the selection procedure that implied automatic exclusion from the standard treatment, ie, endarterectomy.
References
1. Dietz A, Berkefeld J, Theron JG, Schmitz-Rixen T, Zanella FE, Turowski B, Steinmetz H, Sitzer M. Endovascular treatment of symptomatic carotid stenosis using stent placement: long-term follow-up of patients with a balanced surgical risk/benefit ratio. Stroke. 2001; 32: 1855–1859.
2. Rothwell PM, Warlow CP, for the European Carotid Surgery Trialists’ Collaborative Group. Prediction of benefit from carotid endarterectomy in individual patients: a risk-modelling study. Lancet. 1999; 353: 2105–2110.[CrossRef][Medline] [Order article via Infotrieve]
3. European Carotid Surgery Trialists’ Collaborative Group. Randomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST). Lancet. 1998; 351: 1379–1387.[CrossRef][Medline] [Order article via Infotrieve]
4. Major ongoing stroke trials. Stroke. 2002; 33: 646–655.
Institute of Neuroradiology
Department of Neurology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
Response
We thank Drs Barth and Bassetti for their critical comments on the article by Dietz et al,1 but we believe that we can clarify some points they raised. Within the last decade, several investigations provided evidence that factors other than the occurrence of ischemic symptoms and degree of stenosis modulate the risk of stroke and death associated with carotid stenosis. For instance, the occurrence of transient monocular blindness is associated with nearly the half the risk of ipsilateral stroke as that associated with cerebral ischemic symptoms.2 Furthermore, the appearance of an irregular/ulcerative plaque surface morphology on angiography was associated with an 
1.8-fold increased risk of ipsilateral stroke in medically treated patients.3,4 After the first ischemic event, the subsequent risk of ipsilateral stroke decreases continuously within the following months.5 On the other hand, female sex is associated with a higher risk of perioperative stroke or death in both symptomatic and asymptomatic patients.6,7 Thus, confirmed by these independent findings from studies other than the European Carotid Surgery Trial, it seems to be most likely that the risk appraisal function developed by Rothwell and Warlow6 is valid and can be used to estimate the individual risk and benefit from endarterectomy in patients with symptomatic high-grade carotid stenosis.
In our study, patient selection was made by an interdisciplinary conference between neurologists, vascular surgeons, and interventional neuroradiologists who selected cases with a suggested increased surgical risk based not only on the above-mentioned Rothwell score but also on a substantial amount of comorbidity or extracranial multivessel disease. All patients were informed about the proven standard therapy of carotid endarterectomy and the new and not finally evaluated character of carotid stenting. The reasons for deviation from standard treatment were explained, as well as the possibility to convert to standard surgical treatment without negative consequences. Perhaps we stressed the role of the Rothwell score too much in the article, but the positive results of our follow-up study with a low periprocedural complication rate and a combined stroke and death rate of 5% within 22 months may support the notion that primary stenting may be a safe and potentially effective treatment option in subgroups of patients with a balanced surgical risk-to-benefit ratio. We still think that it is ethical to investigate and evaluate therapeutic alternatives for this group of patients before we have the final data from a randomized carotid stent trial.
References
1. Dietz A, Berkefeld J, Theron JG, Schmitz-Rixen T, Zanella FE, Turowski B, Steinmetz H, Sitzer M. Endovascular treatment of symptomatic carotid stenosis using stent placement: long-term follow-up of patients with a balanced surgical risk/benefit ratio. Stroke. 2001; 32: 1855–1859.
2. Benavente O, Eliasziw M, Streifler JY, Fox AJ, Barnett HJ, Meldrum H, for the North American Symptomatic Carotid Endarterectomy Trial Collaborators. Prognosis after transient monocular blindness associated with carotid-artery stenosis. N Engl J Med. 2001; 345: 1084–1090.
3. Rothwell PM, Gibson R, Warlow CP. Interrelation between plaque surface morphology and degree of stenosis on carotid angiograms and the risk of ischemic stroke in patients with symptomatic carotid stenosis: on behalf of the European Carotid Surgery Trialists’ Collaborative Group. Stroke. 2000; 31: 615–621.
4. Eliasziw M, Streifler JY, Fox AJ, Hachinski VC, Ferguson GG, Barnett HJ. Significance of plaque ulceration in symptomatic patients with high-grade carotid stenosis: North American Symptomatic Carotid Endarterectomy Trial. Stroke. 1994; 25: 304–308.[Abstract]
5. Barnett HJ, Taylor DW, Eliasziw M, Fox AJ, Ferguson GG, Haynes RB, Rankin RN, Clagett GP, Hachinski VC, Sackett DL, Thorpe KE, Meldrum HE. Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis: North American Symptomatic Carotid Endarterectomy Trial Collaborators. N Engl J Med. 1998; 339: 1415–1425.
6. Rothwell PM, Warlow CP. Prediction of benefit from carotid endarterectomy in individual patients: a risk-modelling study: European Carotid Surgery Trialists’ Collaborative Group. Lancet. 1999; 353: 2105–2110.[CrossRef][Medline] [Order article via Infotrieve]
7. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA. 1995; 273: 1421–1428.
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