Effects of Carotid Stent Design on Cerebral Embolization

The goal of the proposed study is to contrast the relative efficacy of closed-cell stents versus open-cell stents in preventing periprocedural cerebral embolization in high-risk patients with symptomatic and asymptomatic extracranial carotid stenosis undergoing carotid artery stenting (CAS).

Stroke is responsible for more than 10% of all deaths and much severe disability in developed countries. In the United States, approximately 600,000 new strokes are reported annually, of which 150,000 are fatal, and more than 4,000,000 surviving stroke victims are affected by significant disability. Seventy-five percent of strokes occur in the distribution of the carotid arteries and are considered of a thromboembolic etiology, most of which originate in carotid lesions. Carotid artery stenting (CAS) with cerebral embolic protection is currently the preferred treatment of carotid stenosis in high risk surgical patients, i.e., those with significant comorbidities or a hostile neck from previous surgical procedures or radiation. Although several predictors of adverse outcomes after CAS have been identified, the effects of device characteristics, including stent design, on neurologic adverse events have not been established. The proposed study will be a randomized prospective controlled trial designed to test the hypothesis that the implantation of closed-cell stents for carotid lesions in high-risk patients will be associated with a reduced perioperative cerebral microembolization, as detected by transcranial Doppler and diffusion-weighted magnetic resonance imaging of the brain, and reduced 30-day stroke, myocardial infarction, and death rates when compared with the implantation of open-cell stents.

For patients randomized to the closed-cell stent group, the Xact closed-cell stents were used. The Xact stent is a FDA approved device.

For patients randomized to the open-cell stent group, the Acculink carotid stent was used. The Acculink stent is a FDA approved device.

Patients enrolled in this study arm underwent for carotid stenting using closed stent cell. The graft used in this groups was the Xact closed-cell stent. This type of device is rigid device with dense conposition of the nitinol rigns. Carotid stenting was used on standard fashion using filters as embolic protection device.

Patients enrolled in this study arm underwent for carotid stenting using open stent cell stents. This type of stent is a tube shaped graft composed of flexible nitinol rings. The device used in this group was the Acculinx open-cell stent. Stenting procedure eas performed on standard fashion.Filters were used as embolic protection device.

Bilateral transcranial Doppler scan monitoring of the anterior and middle cerebral arteries was performed using a PMD150-ST3 digital transcranial Doppler pulsed-wave ultrasound scan system (Spencer Technologies, Seattle, Wash) with 2-MHz probes located over the temporal bones above the zygomatic arch. Isolated microembolic signals (MES) were identified from Doppler spectras according to the criteria given by the Consensus Committee of the Ninth International Cerebral Hemodynamic Symposium. If the number of MES was too high to be counted separately, heartbeats with microemboli were counted as microembolic showers. To avoid confusion, MES detected during contrast injection were excluded from the analysis. For analysis purposes, the procedure was divided into the following phases: lesion crossing, filter deployment, IVUS examination, predilation, stent deployment, postdilatation (when applicable), and filter removal.

Inclusion Criteria: Subject is at high risk for carotid endarterectomy due to either anatomic or co-morbid conditions; AND Symptomatic patients (TIA or non-disabling stroke within 6 months of the procedure), with carotid stenosis ≥ 50% as diagnosed by angiography, using NASCET methodology (50); OR Asymptomatic patients with carotid stenosis ≥ 80% as diagnosed by angiography, using NASCET methodology Exclusion Criteria: Conditions that interfere with the evaluation of endpoints Subject has anticipated or potential sources of cardiac emboli Subject plans to have a major surgical procedure within 30 days after the index procedure. Subject has intracranial pathology that makes the subject inappropriate for study participation. Subject has a total occlusion of the ipsilateral carotid artery (i.e., CCA). Severe circumferential lesion calcification that may restrict the full deployment of the carotid stent. Carotid stenosis located distal to the target stenosis that is more severe than the target stenosis.

Timaran CH, Rosero EB, Higuera A, Ilarraza A, Modrall JG, Clagett GP. Randomized clinical trial of open-cell vs closed-cell stents for carotid stenting and effects of stent design on cerebral embolization. J Vasc Surg. 2011 Nov;54(5):1310-1316.e1; discussion 1316. doi: 10.1016/j.jvs.2011.05.013. Epub 2011 Jul 1.