During the periprocedural phase, correct technique, operator experience, accurate lesion and patient selection and the adequate use of an embolic protection device are essential factors to improve results, writes Koen Deloose, with his colleagues Marc Bosiers and J Callaert, investigators in the CLEAR ROAD trial.
Several available studies show that carotid stenting works in the long run. According to the CREST data, there are no differences between carotid endarterectomy and carotid artery stenting with regard to mortality, freedom from target lesion revascularisation and ipsilateral stroke from 30 days onwards until four years. Similar findings are reported in the EVA-3S and SPACE trials which show comparable secondary stroke rates in endarterectomy and stenting groups between 30 days and two to four years.
Yet, with carotid artery stenting, there is definitely room for peri-procedural improvement (0–30 days). During this phase, correct technique, operator experience, accurate lesion and patient selection and the adequate use of an embolic protection device are essential factors to improve results.
In our view, immediately post-procedure, once the embolic protection device has been removed, the presence of an ideal stent is crucial. It has been recognised that the stent itself may substantially add to embolic protection in carotid artery stenting by adequate scaffolding of the plaque. The ideal properties of a carotid stent are a well-balanced mix of high flexibility and conformability, to accommodate tortuous anatomy (as we have with open cell designed stents), as well as high plaque coverage, to prevent small and late embolization (as we have with closed cell designed stents).
It is clear from several studies that small and late emboli are the biggest challenge for the carotid stenting. We did not see any differences in major stroke rates between groups that received stenting and those that underwent an endarterectomy (p=0.2005) in the CREST data, but for minor strokes, the data told a different story (p=0.0088).
In the Belgian-Italian dataset, analysing more than 3,000 carotid artery stenting procedures, with a total of 3.6% stroke– death rate in the symptomatic subgroup, a clear reduction of neurological events was detected in the stent group with minimal free cell areas <5mm² compared to bigger “free cell area” stents (p=0.048). The same data also a showed trend towards advantage for “minimal free cell area” stents with regard to late events in the symptomatic population (p=0.024) over the so-called closed cell stents. Also a SPACE subanalysis showed a non-inferiority with regard to 30-day major adverse events if only the closed cell stent subgroup was taken in to account. These findings are confirmed by a publication of Schnaudigel et al: a higher incidence of ipsilateral diffusion weighted imaging lesions in the open cell stent group (p<0.01) compared to closed cell stents. De Donato et al showed with intravascular optical coherence tomography that micro-defects after stent deployment are frequent and are related to the design of implanted stents. Stent malapposition is more frequent with closed cell stents, while plaque prolapse and fibrous cap rupture are more common with open cell stents.
Recent progress in stent design development should allow us to improve the early carotid stent results and close the gap with peri-procedural endarterectomy-results. The 0.014”, rapid exchange, 5F compatible, self-expanding double layer mesh carotid stent RoadSaver (Terumo) consists of an outer braided nitinol macromesh and a dedicated inside nitinol micromesh scaffold. With an extremely high plaque coverage (minimal free cell area of 0.381mm²), a superior in-vessel flexibility and excellent wall appositioning, the stent acts as an anatomy adapting, metallic, covered, sustained embolic protection implant. Also, the low profile, the extreme flexibility in the undeployed state and the re-sheathable/repositionable characteristics of this device offer advantages in terms of crossability and precise stent placement.
Due to positive initial experiences with the device in carotid stenting procedures, the authors decided to initiate the CLEAR-ROAD trial. This study is a physician-initiated, prospective, multicentre, carotid trial investigating the efficacy of endovascular treatment of carotid artery disease with the multilayer Roadsaver stent in 100 patients. The objective of the study is to evaluate the clinical outcome (up to one year) of carotid artery stenting with this stent in subjects at high risk for endaterectomy. Ostial common carotid artery lesions, carotid occlusions and intraluminal thrombus, previous carotid artery stenting and evolving stroke or major haemorrhage are logical exclusion criteria. The primary endpoint is the 30-day rate of major adverse events, defined as the cumulative incidence of any peri-procedural death, stroke or myocardial infarction. A pre- and post-procedural angiographic control to evaluate the stent behaviour and a follow-up with clinical and duplex ultrasound assessments at discharge, one, six and 12 months is planned. The first enrolments are planned in March and initial preliminary results will be expected by the end of this year. ‰Û¬
Koen Deloose, Marc Bosiers and J Callaert are with the Department of Vascular Surgery AZ Sint Blasius Hospital, Dendermonde, Belgium. The authors have reported no disclosures pertaining to the article
