Several Predictors Found for Cerebral Embolization After Protected Carotid Stenting

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Age, hypertension, lesion morphology, and aortic arch type are predictors of procedure-related cerebral embolization during carotid artery stenting (CAS), according to a study published online May 28, 2013, ahead of print in Circulation: Cardiovascular Interventions. In addition, age, significant contralateral carotid stenosis, and complex aortic arch type were found to be predictors of bilateral ischemic lesions.

Joachim Schofer, MD, PhD, of Hamburg University Cardiovascular Center (Hamburg, Germany), and colleagues performed pre-and post-intervention diffusion-weighted magnetic resonance imaging (DW-MRI) on new cerebral ischemic lesions in 728 (86.9%) of 837 consecutive patients undergoing CAS with embolic protection from February 2011 to December 2010.

Predictors Defined

New lesions were found in one-third (n = 241) of patients—75% exclusively in the ipsilateral hemisphere and 25% in both the ipsilateral and the contralateral hemisphere.

Multivariate analysis showed that age, aortic arch type, hypertension, lesion length, and eccentric lesions were positively associated with new ischemic lesions, whereas calcified lesions were negatively correlated (table 1).

Table 1. Risk Factors for New Cerebral Ischemic Lesions

 
In addition, age and contralateral internal carotid artery stenosis > 50% were found to be significant risk factors for new ischemic lesions in the contralateral hemisphere, though no association was found with aortic arch type I. Even so, aortic arch type II was a significant predictor of contralateral cerebral lesions, and aortic arch type III showed a trend toward a higher incidence of these lesions (table 2).

Table 2. Risk Factors for New Contralateral Ischemic Lesions

 

MACCE at 30 days was observed in 15 patients (1.79%) and consisted of 9 minor strokes, 5 major strokes, and 1 death. All but 1 stroke occurred within 12 hours after CAS, and the majority occurred in the ipsilateral hemisphere (n = 10).

Clinical Implications To Be Determined

“The present findings are an important step toward the understanding of the best revascularization alternatives for patients with carotid artery disease,” Dr. Schofer and colleagues write. “However, the clinical implications of ischemic lesions are not yet fully understood.”

The focus of the study, they continue, was to identify a subgroup of patients at particularly high risk for cerebral embolization during CAS in order to characterize a group of patients at high risk for stroke.

“Beyond age, which has been shown to be a predictor of periprocedural cerebral embolic lesions elsewhere, characteristics of lesions and patients have been identified, which may serve as a basis for individual treatment decisions,” they say. “Elderly patients with complex aortic arches and long lesions may be at particular risk for cerebral embolic lesions, which, at least in part, cannot be prevented by embolic protection systems.”

Significance of Diffusion MRI Findings Unclear

In an e-mail communication with TCTMD, Christopher J. White, MD, of Ochsner Heart and Vascular Institute (New Orleans, LA), said the findings are confirmatory of several previous studies. However, the reported MACCE rate is “perhaps unbelievably low,” he said. “It appears the patients were not examined before and after the procedure by an independent neurologist, which leads to underreporting of events and weakens any linkage between the surrogate DW-MRI finding and any clinical implication.”

With that said, Dr. White explained that DW-MRI lesions are “considered ‘surrogates’ for emboli, but their clinical significance is not known. There continues to be debate about their meaning and their importance.”

The strongest predictor was hypertension, he continued, which was present in 88.4% of patients.  A type III aortic arch “was also important, but this information was only available in 40% of the patients, which weakens this association,” Dr. White observed.

Going forward he said he would like to see “controlled trials using both transcranial Doppler as well as DW-MRI to determine the benefit of specific types of embolic protection devices.” Unanswered questions include finding the most effective filter, determining if proximal protection is better than the best filter, and defining any differences between the 2 types of proximal protection, Dr. White concluded.

 

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Source:
Bijuklic K, Wandler A, Varnakov Y, et al. Risk factors for cerebral embolization after carotid artery stenting with embolic protection: A diffusion-weighted magnetic resonance imaging study in 837 consecutive patients. Circ Cardiovasc Interv. 2013;Epub ahead of print.

 

 

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