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Department of Radiology, Ochsner Clinic Foundation, 1514 Jefferson Highway, New Orleans, LA 70121. e-mail: ebluth@ochsner.org
Editor:
I read with interest the article entitled "Carotid Angioplasty and Stent Placement: Comparison of Transcranial Doppler US Data and Clinical Outcome with and without Filtering Cerebral Protection Devices in 509 Patients" by Dr Vos and colleagues in the February 2005 issue of Radiology (1). In the study by these authors, there was a demonstration of an association between the volume of microemboli and macroemboli in association with protection devices for patients who underwent angioplasty and stent placement.
The article is of great importance, but it did not include the considerable work that has been done regarding plaque characterization, plaque instability, and the presence of intraplaque hemorrhage within plaque. With ultrasonography (US), plaque has been successfully classified as heterogeneous or homogeneous, with heterogeneous plaque being associated with intraplaque hemorrhage and instability (2–10).
It would have been interesting for the authors to have classified the plaque prior to angioplasty and stent placement to determine if there was a higher incidence of micro- or macroemboli in heterogeneous plaque when angioplasty and stent placement were performed. It would seem that in combining the work by these authors and the information in the literature on US there would be a safe subgroup of patients who have homogeneous plaque, who should undergo angioplasty and stent placement. This is the majority of patients. On the other hand, 15% of patients who have heterogeneous plaque (particularly class 1) would be more likely to produce macroemboli and microemboli and subsequent morbidity because of the intraplaque hemorrhage and the potential for rupture when the plaque environment is disturbed by a catheter. As a result, it would seem logical that stenosis in these patients should be resolved with endarterectomy rather than angioplasty and stent placement. By combining the work of Dr Vos and colleagues (1) with what is known through the literature on US, it appears that a safer subgroup for performing carotid angioplasty and stent placement can be determined at this time.
References
* Departments of Radiology, St Antonius Hospital Koekoekslaan 1, 3435 CM Nieuwegein, the Netherlands. e-mail: j.a.vos@antonius.net
Clinical Neurophysiology, St Antonius Hospital Koekoekslaan 1, 3435 CM Nieuwegein, the Netherlands.
We would like to thank Dr Bluth for his valuable comments on our article (1). Dr Bluth raises a very important issue in his letter, namely the identification of patients at risk prior to therapy.
The main hazard of carotid angioplasty and stent placement is the possible dislodgment of material from the diseased artery, leading to cerebral embolization. In our study, the number of embolic signals detected in the middle cerebral artery at transcranial Doppler US was used as a measure of the amount of embolic material. This method has been used by several investigators to assess embolic load during carotid angioplasty and stent placement (2–4). We were surprised to find a significantly higher embolic load in the protected subgroup compared with that in the unprotected subgroup in our series. We did not use plaque characteristics in our evaluation, as these data were not routinely available. Plaque characteristics therefore did not play any role in the choice of whether to use a cerebral protection device and hence did not influence results in our series.
An anechoic appearance within plaque at the carotid bifurcation has been shown to be associated with a higher embolic load during carotid angioplasty and stent placement (5–7), possibly permitting patients at higher risk for periprocedural embolic events to be identified beforehand. This information therefore might be used as a selection criterion to favor carotid endarterectomy. In cases where carotid endarterectomy is not possible, the finding of anechoic plaque could be used to electively use a cerebral protection device during carotid angioplasty and stent placement. In the majority of cases, when no anechoic appearance is encountered, this regimen would obviate the need for a cerebral protection device during carotid angioplasty and stent placement. This could potentially both save money and reduce complications, as the use of cerebral protection devices during carotid angioplasty and stent placement has been shown to be associated with its own complications (8,9). The indiscriminate use of these devices may therefore be ill advised.
References
This article has been cited by other articles:
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  D. Pelz, T. Andersson, M. Soderman, P. Lylyk, and M. Negoro Advances in Interventional Neuroradiology 2005 Stroke, February 1, 2006; 37(2): 309 - 311. [Full Text] [PDF]
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