***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: Background and Purpose — Little is known about the significance of patient characteristics , clinical indications , and technical details on the risk of carotid angioplasty and stenting ( CAS ) . The purpose of this study was to test these parameters as to their predictive value for the peri-interventional risk of CAS . Methods — Pro-CAS is a prospect i ve , multicenter registry of CAS . Logistic regression analysis of possible predictive factors was performed on 5341 interventions that had been entered by 25 clinical centers between July 1999 and June 2005 . Results — The combined in-hospital mortality and stroke rate was 3.6 % . The following were found to be significant predictors of peri-interventional stroke and death : center experience ( ≤50 versus 51 to 150 versus ≥151 interventions ) , age , prior symptoms , primary intervention as compared with intervention for restenosis , angioplasty without stent , predilatation , and heparin dosage > 5000 IU . No statistically significant result was found for year of intervention , patient volume , gender , interval between symptoms and CAS , ocular versus neurological symptoms , side of CAS , degree of stenosis of the target lesion , presence of contralateral high-degree stenosis or occlusion , method of gaining access to the carotids , stent type , and use of a protection system . Conclusions — Our findings underline the need for dedicated training and strict credentialing rules for CAS . In addition , they might help to identify subgroups of patients at differential risk for CAS and carotid endarterectomy and yield a basis for correcting risks due to differences in case mix in reports about CAS 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 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 rct ion or death within 30 days of treatment , treatment- related cranial nerve palsy or haematoma . Restenosis ( > 70 % ) on ultrasound follow-up , economic measures and quality of life will also be analysed . The sample size is estimated at 1,500 patients , which will provide 95 % confidence intervals of ± 3.0 percentage points for the outcome measure of 30-day disabling stroke and death rate and ± 3.3 percentage points for the outcome measure of death or stroke during follow-up . The trial office monitors outcome events at individual centres and a rate of events above a given threshold triggers a blinded assessment of the events , su bmi tted to the chairman of the data -monitoring committee . Conclusions : The ICSS protocol incorporates a number of novel features to ensure patient safety , including the concept of probationary centres , proctoring of inexperienced investigators and monitoring of individual centre results on an ongoing basis . The protocol is also design ed to mirror routine clinical practice as far as possible , so that the results will be widely applicable and relevant to determining the place of carotid stenting in clinical practice in the future BACKGROUND Carotid stenting is a potential alternative to carotid endarterectomy but whether this technique is as 
    Output:
    
Endovascular treatment is associated with an increased risk of peri-procedural stroke or death compared with endarterectomy .
However , this excess risk appears to be limited to older patients .