Invited commentary

Abstract

The ARCHeR trial represents an important contribution that provides data regarding the safety and efficacy of the Guidant Acculink and Accunet carotid stent and filter systems and also adds to the growing data pool on the results of carotid stenting in high-risk patients. It is important, however, that the limitations of this study be fully understood. The ARCHeR trial is not a prospective, randomized, controlled trial. It is not a comparative trial at all. It is an industry-sponsored, multi-institutional case registry. This registry was developed in order to accumulate a body of data on the performance of the Guidant products with a major goal of gaining Food and Drug Administration approval. It must be noted that the majority of the coauthors of this paper are either Guidant employees or consultants or receive financial support from Guidant. In order to garner Food and Drug Administration approval, the authors needed to show that the results of treatment with their product were not inferior to the results of standard treatment (carotid endarterectomy; CEA). As a basis for comparison, they used historical controls derived from selected series in the literature. By methods that are difficult to understand, they arrived at a control group (CEA) composite adverse event rate of 14.4%, to which they compare their stenting results (composite adverse event rate of 9.6%). Bias in selection of the series used to determine their control group adverse event rate is evident. The control group even included series of patients undergoing simultaneous coronary artery bypass grafting and CEA, a group in which stroke and mortality rates are high and in which the majority of strokes and deaths are not CEA related. In their appendix, the authors cite many series to support their control group adverse event rate, but they omit several series as well. For example, in 2003, Gasparis et al1Gasparis A.P. Ricotta L. Cuadra S.A. Char D.J. Purtrill W.A. Van Bemmelen P.S. et al.High risk carotid endarterectomy fact or fiction?.J Vasc Surg. 2003; 37: 40-46Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar reported on 228 high-risk CEA patients.1Gasparis A.P. Ricotta L. Cuadra S.A. Char D.J. Purtrill W.A. Van Bemmelen P.S. et al.High risk carotid endarterectomy fact or fiction?.J Vasc Surg. 2003; 37: 40-46Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar Their definition of high risk was at least as stringent as that used by the ARCHeR team (age >80 years, myocardial infarction in the prior 6 months, New York Heart Association class III or IV angina, Canadian Heart Association (CHA) class III or IV congestive heart failure, steroid- or oxygen-dependent chronic obstructive pulmonary disease, creatinine of 3 mg/dl or greater, contralateral occlusion, carotid reoperation, prior neck irradiation, or high lesion). The 30-day results of CEA in these patients included mortality, myocardial infarction, and stroke rates of 0.4%, 0.9%, and 0.9%, respectively, with a combined stroke/death rate of 1.3%. There are other reports of CEA in high-risk patients that call into question the validity of the ARCHeR authors’ control group adverse event rate.2Reed A.B. Gaccione P. Belkin M. Donaldson M.C. Mannick J.A. Whittemore A.D. et al.Preoperative risk factors for carotid endarterectomy defining the patient at high risk.J Vasc Surg. 2003; 37: 1191-1199Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar, 3Ouriel K. Hertzer N.R. Beven E.G. O’Hara P.J. Krajewski L.P. Clair D.G. et al.Preprocedural risk stratification identifying an appropriate population for carotid stenting.J Vasc Surg. 2001; 33: 728-732Abstract Full Text Full Text PDF PubMed Scopus (166) Google Scholar Even if the reader discounts the comparative data in this article, the results are interesting. In symptomatic patients, the 30-day stroke, death, and combined stroke/death rates were 10.9%, 2.2%, and 11.6%, respectively. In asymptomatic patients, the rates were 3.8%, 2.0%, and 5.4%. It should be noted that just as in the CEA trials, the results achieved in ARCHeR by experienced carotid interventionalists in large programs may not be reflective of the results likely to be achieved by less highly selected or experienced interventionalists. The data on durability are also notable. Although the target lesion revascularization rate at 1 year was only 2.2%, fully 26% of patients had 50% to 69% restenosis, and 5% had more than 70% restenosis at 1 year. In the relatively small number of patients followed up for 2 and 3 years, the incidence of 50% to 69% and greater than 70% restenosis did not increase. While the ARCHeR trial contains a wealth of data on the results of carotid stenting with the Guidant products, it does not provide a valid assessment of the relative merits of stenting and CEA in the management of high-risk patients. Definitive assessment of the relative merits of stenting and CEA awaits properly designed and conducted prospective randomized controlled trials.