***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Rationale Carotid endarterectomy ( CEA ) and medical therapy were shown superior to medical therapy alone for symptomatic ( ge;50 % ) and asymptomatic ( ≥60 % ) stenosis .  Carotid angioplasty stenting ( CAS ) offers a less invasive alternative . Establishing safety , efficacy , and durability of CAS requires rigorous comparison with CEA in symptomatic and asymptomatic patients . Aims The objective is to compare the efficacy of CAS versus CEA in patients with symptomatic ( ≥50 % ) or asymptomatic ( ≥60 % ) extracranial carotid stenosis . Design The Carotid Revascularization Endarterectomy vs. Stenting Trial ( CREST ) is a prospect i ve , r and omized , parallel , two-arm , multi-center trial with blinded endpoint adjudication . Primary endpoints are analyzed using st and ard time-to-event statistical modeling with adjustment for major baseline covariates . Primary analysis is on an intent-to-treat basis . Study Outcomes The primary outcome is the occurrence of any stroke , myocardial infa rct ion , or death during a 30-day peri-procedural period , and ipsilateral stroke during follow-up of up to four years . Secondary outcomes include restenosis and health-related quality of life Background : Our aim was to determine whether filter protection reduces embolisation to the brain during  carotid artery stenting ( CAS ) . Methods : Thirty patients with symptomatic carotid artery stenosis ≧70 % ( North American Symptomatic Carotid Endarterectomy Trial ) were r and omly assigned to filter-protected or unprotected CAS . Diffusion-weighted magnetic resonance imaging ( DWI ) of the brain was performed before and at 3 time points after CAS . In a subset of patients , high-intensity transient signals on transcranial Doppler ( TCD ) were recorded with categorisation of emboli . Data were independently review ed off-site . Results : There were no significant differences in mean age , proportion of octogenarians or presenting symptoms between the groups . On procedural DWI ( 1–3 and 24 h after stenting ) , there were 7/24 ( 29 % ) and 4/22 ( 18 % ) new lesions in protected and unprotected patients respectively ( p = 0.38 ) . At 30 days there were 9/33 ( 26 % ) and 4/33 ( 12 % ) lesions in protected and unprotected patients , respectively ( p = 0.1 ) . On TCD there were significantly more signals in total as well as particulate emboli  during filter-protected CAS ( 426.5 and 251.3 ) than during unprotected CAS ( 165.2 and 92 ) – p = 0.01 and 0.03 , respectively . Conclusions : Filter-protected CAS is associated with an increase in new lesions on DWI and significantly higher rates of total and particulate microembolisation on TCD than unprotected CAS . The clinical significance of these findings requires further study Background —Carotid stenting is a less invasive percutaneous procedure than carotid endarterectomy for the treatment of carotid stenosis . Reports suggest that it can be performed with periprocedural complication rates similar to those of carotid endarterectomy . The purpose of this study was to determine short- and long-term outcomes in the largest prospect i ve cohort of  carotid stenting patients . Methods and Results —This study followed 528 consecutive patients ( 604 hemispheres/arteries ) undergoing carotid stenting .  There was a 0.6 % ( n=3 ) fatal stroke rate and 1 % ( n=5 ) nonstroke death rate at 30 days . The major stroke rate was 1 % ( n=6 ) , and the minor stroke rate was 4.8 % ( n=29 ) . The overall 30-day stroke and death rate was 7.4 % ( n=43 ) . Over the 5-year study period , the 30-day minor stroke rate improved from 7.1 % ( n=7 ) for the first year to 3.1 % ( n=5 ) for the fifth year ( P < 0.05 for trend ) . The best predictor of 30-day stroke and death was age ≥80 years . After the 30-day period , the incidence of fatal and nonfatal stroke was 3.2 % ( n=31 ) . On Kaplan-Meier analysis , the 3-year freedom from ipsilateral or fatal stroke was 92±1 % . Conclusions —Experience from a single group of operators demonstrates that carotid stenting can be performed with an acceptable 30-day complication rate . Late follow-up also demonstrates a low rate of fatal and nonfatal stroke . These results suggest that carotid stenting may be comparable to carotid endarterectomy , and it underscores the clinical equipoise and premise for the National Institute of Health – supported , r and omized Carotid Revascularization Endarterectomy Versus Stent Trial comparing carotid stenting with carotid endarterectomy Summary Background In the Carotid and Vertebral Artery Transluminal Angioplasty Study ( CAVATAS ) , early recurrent carotid stenosis was more common in patients assigned to  endovascular treatment  than it was in patients assigned to endarterectomy ( CEA ) , raising concerns about the long-term effectiveness of endovascular treatment . We aim ed to investigate the long-term risks of restenosis in patients included in CAVATAS . Methods 413 patients who were r and omly assigned in CAVATAS and completed treatment for carotid stenosis ( 200 patients had endovascular treatment and 213 patients had endarterectomy ) had prospect i ve clinical follow-up at a median of 5 years and carotid duplex ultrasound at a median of 4 years . We investigated the cumulative long-term incidence of carotid restenosis after endovascular treatment and endarterectomy , the effect of the use of stents on restenosis after endovascular treatment , risk factors for the development of restenosis , and the effect of carotid restenosis on the risk of recurrent cerebrovascular events . Analysis was by intention to treat . This study is registered , number IS RCT N01425573 . Findings Severe carotid restenosis ( ≥70 % ) or occlusion occurred significantly more often in patients in the endovascular arm than in patients in the endarterectomy arm ( adjusted hazard ratio [ HR ] 3·17 , 95 % CI 1·89–5·32 ; p<0·0001 ) . The estimated 5-year incidence of restenosis was 30·7 % in the endovascular arm and 10·5 % in the endarterectomy arm . Patients in the endovascular arm who were treated with a stent ( n=50 ) had a significantly lower risk of developing restenosis of 70 % or greater compared with those treated with balloon angioplasty alone ( n=145 ; HR 0·43 , 0·19–0·97 ; p=0·04 ) . Current smoking or a history of smoking was a predictor of restenosis of 70 % or more ( 2·32 , 1·19–4·54 ; p=0·01 ) and the early finding of moderate stenosis ( 50–69 % ) up to 60 days after treatment was associated with the risk of progression to restenosis of 70 % or more ( 3·76 , 1·88–7·52 ; p=0·0002 ) . The composite endpoint of ipsilateral non-perioperative stroke or transient ischaemic attack occurred more often in patients in whom restenosis of 70 % or more was diagnosed in the first year after treatment compared with patients without restenosis of 70 % or more ( 5-year incidence 23 % vs 11 % ; HR 2·18 , 1·04–4·54 ; p=0·04 ) , but the increase in ipsilateral stroke alone was not significant ( 10 % vs 5 % ; 1·67 , 0·54–5·11 ) . Interpretation Restenosis is about three times more common after endovascular treatment than after endarterectomy and is associated with recurrent ipsilateral cerebrovascular symptoms ; however , the risk of recurrent ipsilateral stroke is low . Further data are required from on-going trials of stenting versus endarterectomy to ascertain whether long-term ultrasound follow-up is necessary after carotid revascularisation . Funding British Heart Foundation ; UK National Health Service Management Executive ; UK Stroke Association OBJECTIVE The effect of stent design on cerebral embolization has not been established . The purpose of this trial was to contrast the incidence of sub clinical cerebral embolization in high-risk patients undergoing carotid artery stenting ( CAS ) with open-cell vs closed-cell stents .  METHODS During an 18-month period , 40 patients were r and omized ( 1:1 ) to undergo CAS with open-cell ( Acculink , n = 20 ) or closed-cell stents ( Xact , n = 20 ) . A single filter device for embolic protection ( Accunet filter ) was used . Transcranial Doppler (TCD)-detected microembolic signals ( MES ) during CAS and preprocedural and 24-hour postprocedural diffusion-weighted magnetic resonance imaging ( DW-MRI ) were used to determine cerebral embolization . Univariate and nonparametric analyses were used to assess associations between stent design and cerebral embolization . RESULTS CAS was performed in 17 symptomatic patients ( 43 % ) and 23 asymptomatic patients ( 57 % ) with a similar number of open-cell and closed-cell stents ( 9/8 and 11/12 , respectively ) . The total and poststenting median ipsilateral MES counts detected by TCD were 264 ( interquartile range [ IQR ] , 222 - 343 ) and 48 ( IQR , 41 - 66 ) for open-cell stents and 339 ( IQR , 163 - 408 ) and 53 ( IQR , 23 - 88 ) for closed-cell stents , respectively ( P > .56 ) . New acute cerebral emboli detected with DW-MRI occurred in 53 % and 47 % of patients undergoing CAS with open-cell and closed-cell stents , respectively ( P = 1.0 ) . The total and ipsilateral median numbers of DW-MRI lesions between groups were not statistically significantly different ( ie , 2 [ IQR , 0 - 4 ] and 1 [ IQR , 0 - 3 ] for open-cell stents and 1 [ IQR , 0 - 3 ] and 1 [ IQR , 0 - 2 ] for closed cell-stents , respectively ; P > .4 ) . One asymptomatic patient undergoing CAS with an open-cell stent sustained a minor stroke ; the 30-day stroke-death rate in this series was 2.5 % . CONCLUSION Cerebral embolization , as detected by TCD and DW-MRI , occurs with similar frequency after CAS with open-cell and closed-cell stents . This r and omized trial does not support the superiority of any stent design with respect to cerebral embolization Background : Carotid stenting avoids general anaesthesia , cranial nerve injury and the discomforts of surgical treatment of carotid stenosis . A systematic review of the r and omised trials showed no overall difference in the major risks of endovascular treatment for carotid stenosis compared with surgery , but the confidence intervals were wide and both methods carried a significant risk of stroke . The use of protection devices appears to improve the safety of endovascular treatment , but there are little r and omised data available about long-term outcomes . We have therefore set up an international , multicentre , r and omised , controlled , open , prospect i ve clinical trial , namely the International Carotid Stenting Study ( ICSS ) , also known as CAVATAS-2 . The objectives of the ICSS are to compare the risks , benefits and cost-effectiveness of a treatment policy of referral for carotid stenting compared with referral for carotid endarterectomy . Methods : Centres are required to have a team with audited expertise in carotid endarterectomy and stenting procedures , including at least one neurologist or stroke physician , a surgeon and an interventionalist . Attendance at a carotid stenting training course is required . Centres with more limited experience can join the trial as probationary centres , but stenting must then be proctored by an experienced interventionalist . Symptomatic patients are included over the age of 40 years with atherosclerotic carotid stenosis , suitable for both stenting and surgery , and are r and omised in equal proportions between carotid endarterectomy and stenting .  Stents and other devices are chosen for use at the discretion of the interventionalists but must be approved by the devices committee . The protocol recommends that a cerebral protection system should be used whenever the operator thinks one can be safely deployed . The combination of aspirin and clopidogrel is recommended to cover stenting procedures . St and ard or eversion endarterectomy is allowed using local or general anaesthesia , shunts or patches . All patients will receive best medical care . Patients will be followed up by neurologists at 30 days after treatment , 6 months after r and omisation and then annually up to 5 years after r and omisation . The primary outcome measure is the difference in the long-term rate of fatal or disabling stroke in any territory between patients r and omised to stenting or surgery . Secondary outcome measures include any stroke , myocardial infa 
    Output:
    
Stenting for symptomatic carotid stenosis is associated with a higher risk of periprocedural stroke or death than endarterectomy .
This extra risk is mostly attributed to an increase in minor , non-disabling strokes occurring in people older than 70 years .
Beyond the periprocedural period , carotid stenting is as effective in preventing recurrent stroke as endarterectomy .
However , combining procedural safety and long-term efficacy in preventing recurrent stroke still favours endarterectomy .
In people with asymptomatic carotid stenosis , there may be a small increase in the risk of periprocedural stroke or death with stenting compared with endarterectomy .