Regarding “Patterns of in-stent restenosis after carotid artery stenting: Classification and implications for long term outcome”

Abstract

With great interest we read the article by Lal et al,1Lal B.K. Kaperonis E.A. Cuadra S. Kapadia I. Hobson 2nd, R.W. Patterns of in-stent restenosis after carotid artery stenting: classification and implications for long-term outcome.J Vasc Surg. 2007; 46: 833-840Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar who found that type of in-stent restenosis (ISR) and diabetes to be an independent predictors of revascularization after carotid angioplasty and stenting (CAS). Furthermore, the type of stent used for CAS was also observed to influence the ISR pattern. ISR occurred more often in patients treated with the Acculink stent (Abbott Vascular, Abbott Park, Ill) compared with the Wallstent (Boston Scientific Corp, Natick, Mass). However, neither in the Methods nor in Table II it is clear how many stents of each type were used. It is therefore not objectified if the observed phenomenon was an absolute or a relative difference. We would like to make two remarks. First, the incidence of ISR is highly dependent on the restenosis definition and the duplex velocity criteria used. Assessment of generally accepted duplex criteria for grading stenosis after carotid endarterectomy has been shown to be not reliable after stenting.2Gröschel K. Riecker A. Schulz J.B. Ernemann U. Kastrup A. Systematic review of early recurrent stenosis after carotid angioplasty and stenting.Stroke. 2005; 36: 367-373Crossref PubMed Scopus (132) Google Scholar, 3Chi Y.W. White C.J. Woods T.C. Goldman C.K. Ultrasound velocity criteria for carotid in-stent restenosis.Cath Cardiovasc Interv. 2007; 69: 349-354Crossref PubMed Scopus (61) Google Scholar Although several stent types have been used in these studies, surprisingly, a comparison for differences in duplex measurements between stent types has not been performed. In an animal experimental study (unpublished data), we evaluated velocity changes due to placement of two different carotid stent types, the Wallstent vs Precise (Cordis, Miami Lakes, Fla). Duplex velocities before and after stenting were measured at five predetermined points. The Precise stent did not cause significant higher velocities compared with baseline. However, the Wallstent was responsible for significantly higher velocities, both in-stent and directly after stenting, compared with the native artery. We concluded that (1) placement of a stent in the carotid artery can cause an increase in duplex velocities in the absence of residual or true in-stent stenosis, (2) alterations are stent-type dependent and do not justify a general approach to new velocity criteria indiscriminately applied to all stents, and (3) vascular laboratories have to develop specific velocity criteria for the evaluation of patients after CAS. Also, 30-day complication rates may vary according to stent type, free cell area, and cell design. Complication rates were highest for open cell types and increased with larger free cell area.4Hart J.P. Peeters P. Verbist J. Deloose K. Bosiers M. Do device characteristics impact outcome in carotid artery stenting.J Vasc Surg. 2006; 44: 725-730Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar In summary, there is growing evidence that clinical outcome, duplex velocities, and need for revascularization are all influenced by type and design of stent. Second, there is currently no way to predict which low-grade lesions will progress to high-grade or symptomatic lesions, or both, which need intervention. Although Lal et al5Lal B.K. Hobson 2nd, R.W. Goldstein J. Chakhtoura E.Y. Durán W.N. Carotid artery stenting: is there a need to revise ultrasound velocity criteria?.J Vasc Surg. 2004; 39: 58-66Abstract Full Text Full Text PDF PubMed Scopus (152) Google Scholar in a previous report described that a higher incidence of residual stenosis after CAS translates into a higher incidence of ISR during follow-up, they failed to establish any correlation between restenosis formation and the existence of residual lesions in their latest report. The authors pursue a classification that offers an opportunity for early identification of high-risk patients for monitoring and treatment. The authors suggest that providing a standardized method of describing restenotic lesions will facilitate further investigations into adjunctive treatments for ISR and improved stent design. We propose that citation of stent type and residual lesions become an essential component of this method. ReplyJournal of Vascular SurgeryVol. 47Issue 6PreviewThank you for your interest in our article relating patterns of in-stent restenosis (ISR) after carotid artery stenting (CAS) to long-term outcomes.1 As stated by you, the key finding was that the type of ISR and diabetes were key independent predictors of future high-grade ISR necessitating revascularization after CAS. You have made several remarks, and we appreciate the opportunity to clarify them. Full-Text PDF Open Archive