Carotid Artery Stenting Using a Closed-Cell Stent-in-Stent Technique for Unstable Plaque

Abstract

Purpose: To examine whether carotid artery stenting (CAS) of stenoses with unstable plaque using a closed-cell stent-in-stent technique prevents plaque protrusion. Materials and Methods: Between December 2014 and August 2018, 35 consecutive patients (mean age 75.8 years; 29 men) with carotid artery stenosis (20 symptomatic) and unstable plaque diagnosed by magnetic resonance imaging were prospectively analyzed. Mean diameter stenosis was 83.5%. All CAS procedures were performed with stent-in-stent placement of Carotid Wallstents using an embolic protection device and conservative postdilation. The technical success rate, incidence of plaque protrusion, ischemic stroke rate within 30 days, and new ipsilateral ischemic lesions on diffusion-weighted imaging (DWI) within 48 hours after CAS were prospectively assessed. Follow-up outcomes included the incidences of ipsilateral stroke and restenosis. Results: The technical success rate was 100%. No plaque protrusion or stroke occurred in any patient. New ischemic lesions were observed on DWI in 10 (29%) patients. During the mean 11.6-month follow-up, no ipsilateral strokes occurred. Two (6%) patients developed asymptomatic restenosis recorded as 53% lumen narrowing and occlusion, respectively. Conclusion: CAS using a closed-cell stent-in-stent technique for unstable plaque may be useful for preventing plaque protrusion and ischemic complications.

Commentary: Double-Layer Carotid Stents: From the Clinical Need, through a Stent-in-Stent Strategy, to Effective Plaque Isolation… the Journey Toward Safe Carotid Revascularization Using the Endovascular Route

“…46,47 Another important concern regarding stent-grafts is the prohibitively high risk of in-stent restenosis, 48,49 which notably has not been seen with the MicroNET mesh-encased self-expanding stent design at up to 3 years. 16 In the August 2019 issue of the JEVT, Myouchin and colleagues 50 share their experience with a stent-in-stent "a priori" implantation strategy using Carotid Wallstents (Boston Scientific, Marlborough, MA, USA) to prevent plaque prolapse in soft, high-risk carotid lesions. This study is important not only because it exemplifies, once more, the clinical need 3,25 for more complete carotid plaque coverage than can be achieved with conventional single-layer carotid stents, but it also indicates some potential stent designdependent concerns for the double metal-layer approach.…”

“…This may lead to incomplete coverage of the region of interest in some cases and to the inadvertent “hanging” of the smaller-diameter (second) device in the common carotid artery in others. 50 Another problem is that the Wallstent design (braiding) is associated with malapposition 51 that may be a predisposing factor for thrombosis (particularly in a prothrombotic milieu) and in-stent restenosis. 52 Indeed, the 6% restenosis rate in the study by Myouchin et al 50 is of substantial concern.…”

“…50 Another problem is that the Wallstent design (braiding) is associated with malapposition 51 that may be a predisposing factor for thrombosis (particularly in a prothrombotic milieu) and in-stent restenosis. 52 Indeed, the 6% restenosis rate in the study by Myouchin et al 50 is of substantial concern. This is particularly relevant as many of the Wallstent-in-Wallstent properties are shared by the novel double metal–layer carotid stent design 51,52 but not by the MicroNET mesh open-cell nitinol frame design.…”

“…As with any carotid stent procedure, aggressive and rigorous dual antiplatelet therapy is essential to minimize the risk of thrombosis. 52 Restenosis and thrombosis with metal-in-metal stenting has been reported 50,52 but may be related to the particular stent design issues.…”

Risk Factors for Residual Stenosis After Carotid Artery Stenting

“…Previous studies also found that it is still difficult to restore fibrous cap integrity after stent implantation; therefore, both the occurrence of long-term restenosis and recent cerebral infarction after stent implantation are related to these properties. Using a closed-cell stent-in-stent technique may result in smaller free-cell area than open-cell stents, which restricts plaque protrusion and, for unstable plaques, may prevent plaque protrusion and ischemic complications (23)(24)(25).…”