The Impact of Free Cell Area in Asymptomatic Patients Undergoing CAS: Results from a Multicentre Registry

Objective: The stent cell design has been advocated as a crucial factor that may impact on reducing cerebrovascular ischaemic events during carotid artery stenting (CAS). New generation dual layer stents (DLSs) seem to perform better than the previous generations but long term data are lacking. The present multi- centre study investigated the association between stent cell design and stroke prevention in asymptomatic patients undergoing CAS. Methods: From January 2006 to January 2022, 1 118 transfemoral CAS procedures were planned in 1 069 patients (males 803, 71.8%) with an asymptomatic severe carotid artery stenosis in six tertiary referral centres. Patients were divided in three groups considering the stent design: open cell (OC), closed cell (CC), and dual layer stents (DLS). Pre-operative data included demographics, comor- bidities, ipsilateral and contralateral carotid artery stenosis degree, occlusion, or previous surgical treatment of the contralateral ca- rotid bifurcation. Post-operative data included technical success (intention to treat basis), access site and systemic complications, and therapy at discharge. Thirty day outcomes were stroke, death (all cause mortality), stroke/death, and myocardial infarction (MI) rates. Follow up outcomes were evaluated at one, 2.5, and five years. Primary follow up outcomes included overall survival, stroke (overall and ipsilateral), and stroke related mortality estimations. Secondary follow up outcomes were restenosis and carotid re- intervention estimations. Data were analysed using the chi squared test and Fisher’s exact test while follow up outcomes were investigated with life table KaplaneMeier curves. The log rank test was used to determine differences between the groups and uni- variate analysis was employed to identify the association between risk factors and stroke rates. A p value < .05 was considered to be statistically significant. Results: In six patients technical success was not achieved (0.5%); thus, 1 112 patients were finally analysed (OC 48.6%, CC 30%, DLS 17.9%); 49 procedures were bilateral (4.4%). Mean age was 73.3  8.2 years (OC 72.9  7.6; CC 73.6  8.4, DLS 74.6  8.2). Thirty day outcomes were stroke rate 2.3% (OC 1.1%, CC 3.4%, DLS 3.8%; p 1⁄4 .018), mortality rate 0.6% (OC 0.9%, CC 0.3%, DLS 0.5%; p 1⁄4 .687), stroke/death rate 2.9% (OC 2.0%, CC 3.7%, DLS 4.2%; p 1⁄4 .151), MI rate 0.2% (OC 0.2%, CC 0.3%, DLS 0.0%; p 1⁄4 .742). A total of 959CAS procedures were followed up with a mean of 50.1  38.8 months (OC 68.8  40.6; CC 43.3  30.1, DLS 17.6  14.5). At one, 2.5, and five years of follow up overall survival was 96%, 91%, 79.2% (OC 96.1%, 92.4%, 81%; CC 96.2%, 89.1%, 77.2%, DLS 95%, 90.1%, 73.1; log rank 2.1, p 1⁄4 .336), overall stroke rate: 0.7%, 1.6%, 1.6% (OC: none, 0.5%, 0.5%; CC: 2%, 3.9%, 3.9%, DLS: none; log- rank 9.7, p 1⁄4 0.008) and 0.3%, 1%, 1.2% ipsilateral (OC: none, 0.3%, 0.3%; CC: 1%, 2.5%, 3.1%, DLS: none; log-rank 8.4, p 1⁄4 0.015), stroke-related mortality rate: 0.2%, 0.7%, 1.2% (OC: none, 0.3%, 0.6%; CC: 0.7%, 1.6%, 2.5%, DLS: none; log-rank 2.5, p 1⁄4 0.283). Restenosis rate was 1.5%, 2.8%, 5.4% (OC 1.7%, 2.7%, 5.5%; CC 2.1%, 3%, 5.8%; DLS: none, 1.5% 3.8%; log rank 0.82, p 1⁄4 .661) and carotid re-intervention rate was 0.9%, 1.9%, 2.9% (OC 1.4%, 2.1%, 3.5%; CC 0.6%, 2%, 2.6%; DLS none; log rank 2.4, p 1⁄4 .296) at one, 2.5, and five years, respectively. The risk factor analysis shows a higher significant incidence of dyslipidaemia (p 1⁄4 .0001), hypertension (p 1⁄4 .0001), smoking habit (p 1⁄4 .001), and a severe degree of stenosis (p 1⁄4 .001) in the CC and DLS groups. These data may explain the 30 day stroke rates in these groups being these stents selected to treat a high risk population. The 2.5 and five year KaplaneMeier curves showed higher incidence of overall (p 1⁄4 .008) and ipsilateral (p 1⁄4 .015) stroke rates in the CC group. The univariate analysis demonstrated that ipsilateral stroke rate was influenced by age (p 1⁄4 .005) and peripheral artery dis- ease (p 1⁄4 .015). Conclusion: In this study, CC stents and DLS showed higher rate of post-operative stroke probably because they were used to treat a risky population. DLS performed better than OC and CC stents in terms of five year stroke prevention