​Objective

To evaluate the incidence and the time of onset of early microembolism after carotid artery stenting (CAS) with two different dual-layer micromesh stents (Roadsaver^TM or CGuard^TM) and to assess the role of Diffusion-Weighted Magnetic Resonance Imaging (DW-MRI) as a predictor of microembolization. 

Study Group

• Prospective, Non-randomized,  2-arm, Single-center 
• 1 High-volume Italian canter
• Enrolment between September 2016 and December 2017
• 50 CAS patients (median age 74 years; 33 males)
• 37/50 (74%) patients with primary carotid stenosis had DW-MRI of the carotid plaque pre-procedure, with:
• Qualitative evaluation (signal hyperintensity) 
• Quantitative ADC (apparent diffusion coefficient) measurement  
• Patients presenting with symptomatic stenosis ≥50% (N=29 (58%)) and asymptomatic stenosis ≥ 80% (N=21 (42%)), as per NASCET, were included after multidisciplinary evaluation. 
• Patients >80 years old, with carotid obstruction, endoluminal thrombus, acute stroke within 30 days, myocardial infarction within 72 h, intracranial hemorrhage in the previous 12 months were excluded.
  
• Patients received either Roadsaver^TM (N=25) or CGuard^TM (N=25) stent
  
• All patients had brain DW-MRI pre-procedure, at 1 h, 24 h, and 30 days post-procedure to evaluate the appearance of hyperintense lesions over time. 
• Imaging analysis was performed in a double-blinded fashion by two radiologists.
  
• The clinical evaluation & Duplex ultrasound (DUS) examinations were done at baseline, 24h, and 30 days post-procedure. 
  
• The clinical evaluation included a neurological examination performed by an independent neurologist using the National Institute of Health Stroke Scale (NIHSS). 
  
• Procedural success was defined as residual stenosis after stenting of <30% and no complications. 
• The outcomes of interest were the incidence, volume, and timing of new ischemic brain lesions. 
• Predictors were type of stent used and hyper intensity of the carotid plaque in the pre-procedural DW-MRI

Methods

• The intracranial circulation was evaluated before and after the procedure.
• Co-medication:
  
• Before the procedure, all patients received dual antiplatelet therapy (DAPT; i.e. 100 mg acetyl-salicylic acid (ASA) and a loading dose of 375 mg clopidogrel (unless already on DAPT). 
  
• During the procedure, ACT-based heparinization was administered using weight adjusted initial dosing. 1 mg of atropine was administered after stent dilatation.
• After the procedure, patients received a daily dose of DAPT (100 mg ASA and 75 mg clopidogrel) for one month, and only ASA thereafter. 
• Embolic protection device (EPD) use: 100% (Emboshield, Abbott Vascular in all patients)
• The same 4 operators with extensive experience (50 CAS/year as first operators in last 10 years) performed all procedures.
• No pre-dilation needed 
• All MRI studies were performed with a 1.5 T scanner (Achieva, Philips, Best, The Netherlands), with a 16-channel PMS SENSE Neurovascular MRI Coil (Philips, Best, The Netherlands). 
• For a detailed summary of different (cerebral & plaque) imaging parameters used, as well as related analyses that were applied, see the original manuscript.
• Two experienced radiologists, double blinded to the study timing and the patient data, evaluated all MRI images qualitatively and quantitatively. 
• In case of disagreement, the examinations were submitted to a senior radiologist
  

Results

• Pre-procedural brain DW-MRI did not evidence any acute ischemic lesions
• Procedural success was achieved in 100% of cases, with no device or procedure-related adverse events recorded
  
• No statistically significant differences were noted between the two stents, in terms of new lesion
  
• Incidence at 1 h (p = 0.23) & 24 h (p = 0.36)
• Volume at 24 h (p = 0.27). 
  
• A total of 34 new asymptomatic (silent) lesions in 19 patients (38%) were reported: 
• 28 (82%) ipsilateral & 6 (18%) contralateral
• 4 (11.8%) at 1 h, 30 (88.2%) at 24 h. 
• The 30-day cerebral DW-MRI showed complete resolution of all lesions and no evidence of new lesion.
  
• The 30-day DUS showed that all ECA and stents were patents without any In-Stent Restenosis (ISR). 
• No major cerebrovascular event or a worsening of the neurological and cognitive conditions was detected upon clinical and neurological evaluations. 
• The incidence of new lesions at 24 h was significantly higher in patients with hyperintense carotid plaques (as per baseline DW-MRI)
• 12/16 (75%) vs. 0/21 (0%) (p < 0.0001). 
• This result was paralleled by the difference in ADC value (0.83 ± 0.21 vs. 1.42 ± 0.52 x 10-3 mm2/s, p = 0.0004)

Conclusion

• No significant differences were evidenced in incidence and volume of intra- and post-procedural ischemic lesions between the dual layer micromesh Roadsaver^TM and CGuard^TM stent.
• The majority of early asymptomatic (silent) brain lesion occurred during the first 24 h after CAS
• The pre-procedural DW-MRI evaluation of the carotid plaque was a reliable predictor of early post-procedural embolization events after CAS.
• Hight plaque signal intensity associated with the increased microembolization incidence