Letter by Makris et al Regarding Article, “Carotid Artery Stenting Versus Carotid Endarterectomy: A Comprehensive Meta-Analysis of Short-Term and Long-Term Outcomes”
To the Editor:
Despite evidence presented from the meta-analysis by Economopoulos et al,1 we believe that the interpretation of the results can be improved if certain limitations are taken into consideration. There is evidence in the literature suggesting that carotid artery stenting (CAS) may be more hazardous in the presence of an unstable carotid plaque.2 Factors that define the vulnerable plaque have been increasingly recognized, and they may affect both the way we evaluate the effectiveness of different treatments (medical, surgical, or interventional), and the way we define indications for them. The imaging in carotid angioplasty and risk of stroke (ICAROS) study,2 for example, showed that more echolucent plaques increase the risk of stroke in CAS. The echomorophology of the plaque has been considered to be an important indicator of plaque stability, and it is strongly associated with the presence of cerebrovascular symptoms as shown in the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study.3 This information is lacking from studies included in this meta-analysis.
There is also accumulating evidence suggesting that statin administration and low-density lipoprotein levels <100 mg/L may have a beneficial effect on plaque morphology and the inflammatory response; thus, they contribute to plaque stabilization.4 low-density lipoprotein levels, as well as the statin administration protocol before and after the procedures, were not systematically reported in any of the studies included in this meta-analysis.
In addition, more emphasis has to be given to the fact that the vast majority of the patients included in this meta-analysis were symptomatic and thus possibly had more unstable plaques. Only a minority of studies actually reported mortality and morbidity in asymptomatic patients postintervention. No solid information about stenting in high-risk, asymptomatic individuals can be provided with the existing evidence. A large number of procedures are currently being performed in asymptomatic individuals around the world, and evidence from this meta-analysis should not be applied to this group before additional evidence comes to light.
Finally, better patient selection and a more individualized approach may improve CAS outcomes.5 Apart from age and those with unfavorable carotid plaque characteristics (vulnerable plaque), carotid anatomy, unfavorable aortic arch anatomy, or even increased carotid artery tortuosity may influence both success rates and rate of adverse event post-CAS.5 The current advances in vascular imaging may enable us to distinguish between those with unfavorable anatomic or morphological plaque characteristics, who are unlikely to benefit from CAS.
We believe that more emphasis should have been given to the above limitations to avoid misinterpretation and overgeneralization of the current evidence. Additional research is needed and future studies should include more specific eligibility criteria to achieve a more individualized approach (ie, careful patient selection). At the same time, future studies should consider and document concurrent use of best medical treatment for every patient, as well as the presence/absence of unstable carotid plaque features.
Gregory C. Makris, MD
Imperial College of London
Division of Surgery
George Geroulakos, MD, PhD
Imperial College of London
Division of Vascular Surgery
Andrew N. Nicolaides, MD, PhD
Cardiovascular Disease Education and Research (CDER)
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- © 2011 American Heart Association, Inc.
- Economopoulos KP,
- Sergentanis TN,
- Tsivgoulis G,
- Mariolis AD,
- Stefanadis C
- Biasi GM,
- Froio A,
- Diethrich EB,
- Deleo G,
- et al