We read with interest the article by Dr Albert W. Chan regarding the performance of carotid artery angioplasty and stenting (CAS) for atherosclerotic disease by a cardiology service (“Carotid artery stenting by a cardiovascular services department in Canada” BCMJ 2009;51[1]:14-19 [11]), and we congratulate the author on his group’s success in 100 patients. We do, however, have some concerns about how this paper will be interpreted by your readers.

Cardiologists perform the majority of CAS procedures in the United States, have published their results widely, and undoubtedly possess the technical skills to perform the procedures successfully. The real issues, however, are appropriate patient selection, management of neurological complications, and clinical follow-up.

The gold standard for the management of symptomatic carotid atherosclerotic disease is carotid endarterectomy (CEA).[1] The management of asymptomatic disease remains controversial, and it is estimated that for these patients 1000 CEAs would need to be performed to prevent approximately 50 strokes at 5 years.[2,3] Over 75% of the patients in Chan’s series were asymptomatic and some had only one questionable high-risk factor for CEA. 

The evidence for treatment of an asymptomatic carotid stenosis prior to heart surgery is questionable.[4] One wonders whether many of the patients in this series were subjected to the low but not insignificant risk of stroke or other complication for no reason.

Some of the patients in this series were offered CAS instead of CEA because “they preferred the less invasive procedure.” There is a widespread perception that CAS is a straightforward, minimally invasive intervention that is easier and safer than CEA and technically no more challenging than a coronary stenting procedure. 

There is no medical evidence supporting this misconception,[5] and until the results of the largest randomized controlled trial of CAS vs CEA are available[6] the performance of CAS is only justifiable in patients with clearly defined contraindications to CEA.

Several of the initial trials of CAS vs CEA were stopped early because of unacceptably high procedural complication rates during CAS. Although current technology has considerably reduced these risks, neurological complications such as stroke and hemorrhage are not uncommon. Some cardiologists may have experience with neurological disease, but who will manage these patients acutely and then follow them during their recovery and rehabilitation?

There are several other statements of concern in this paper. Carotid atherosclerotic disease differs from coronary disease because the primary pathologic process is usually embolic rather than hemodynamic. The evidence for the statement “dilation of a stent to achieve minimal luminal narrowing is crucial for reducing restenosis risk” is not consistent. 

There is good evidence that the use of balloons to dilate carotid arteries to maximum diameter generates more distal emboli and results in greater postoperative hemodynamic instability.[7] There is a low but definite risk of hyperperfusion syndrome following any carotid revascularization procedure, and advocacy of bilateral CAS at once in elderly, possibly asymptomatic patients creates a potentially dangerous model.

In summary, CAS is a procedure in evolution and its appropriate indications are still unclear. Until definitive medical evidence is available, it should be utilized with care and only under established guidelines.[8]

—David M. Pelz, MD, FRCPC
Department of Medical Imaging, University of Western Ontario
—Miguel Bussiere, MD, FRCPC
Department of Neurology, University of Ottawa
—Stephen P. Lownie, MD, FRCSC
Department of Clinical Neurological Sciences, UWO

References

1. North American Symptomatic Carotid Endarterectomy Trial (NASCET) Collaborators. Beneficial effects of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med 1991;325:445-453.
2. Barnett HJM, Meldrum HE, Eliasziw M. The appropriate use of carotid endarterectomy. CMAJ 2002;166:1169-1179.
3. Naylor AR, Gaines PA, Rothwell PM. Who benefits most from intervention for asymptomatic carotid stenosis: Patients or professionals? Eur J Vasc Endovasc Surg 2009;37:625-632.
4. Naylor AR, Mehta Z, Rothwell PM. A systematic review and meta-analysis of 30-day outcomes following staged carotid artery stenting and coronary bypass. Eur J Vasc Endovasc Surg 2009;37:379-387.
5. Eckstein HH, Ringleb P, Allenberg JR, et al. Results of the Stent-Protected Angioplasty versus Carotid Endarterectomy (SPACE) study to treat symptomatic stenoses at 2 years: A multinational, prospective, randomised trial. Lancet Neurol 2008;7:893-902.
6. Barrett KM, Brott TG. Carotid artery stenting versus carotid endarterectomy: Current status. Neurosurg Clin N Am 2008;19:447-458.
7. Bussiere M, Lownie SP, Lee D, et al. Hemodynamic instability during carotid artery stenting: The relative contribution of stent deployment versus balloon dilation. J Neurosurg 2009;110:905-912.
8. Ederle J, Featherstone RL, Brown MM. Randomized controlled trials comparing endarterectomy and endovascular treatment for carotid artery stenosis: A Cochrane systematic review. Stroke 2009;40:1373-1380.