***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 
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    Input: OBJECTIVE This trial was conducted to determine if covered stents offer a patency advantage over bare-metal stents in the treatment of aortoiliac arterial occlusive disease . METHODS The Covered Versus Balloon Exp and able Stent Trial ( COBEST ) , a prospect i ve , multicenter , r and omized controlled trial , was performed involving 168 iliac arteries in 125 patients with severe aortoiliac occlusive disease who were r and omly assigned to receive a covered balloon-exp and able stent or bare-metal stent .  Patient demographic data , clinical signs and symptoms , TransAtlantic Inter-Society Consensus ( TASC ) classification , and preprocedure and postprocedure ankle-brachial index measurements were recorded . The primary end points included freedom from binary restenosis and stent occlusion of the treated area , as determined by ultrasound imaging or quantitative visual angiography , or both . Postprocedural follow-up was at 1 , 6 , 12 , and 18 months . RESULTS Aortoiliac lesions treated with a covered stent were significantly more likely to remain free from binary restenosis than those that were treated with a bare-metal stent ( hazard ratio [ HR ] , 0.35 ; 95 % confidence interval ( CI ) , 0.15 - 0.82 ; P = .02 ) . Freedom from occlusion was also higher in lesions treated with covered stents than in those treated with a bare-metal stent ( HR , 0.28 ; 95 % CI , 0.07 - 1.09 ) ; however , this did not reach statistical significance ( P = .07 ) . Subgroup analyses demonstrated a significant difference in freedom from binary restenosis for covered stents in TASC C and D lesions compared with a bare stent ( HR , 0.136 ; 95 % CI , 0.042 - 0.442 ) . This difference was not demonstrated for TASC B lesions ( HR , 0.748 ; 95 % CI , 0.235 - 2.386 ) . CONCLUSIONS COBEST demonstrates covered and bare-metal stents produce similar and acceptable results for TASC B lesions . However , covered stents perform better for TASC C and D lesions than bare stents in longer-term patency and clinical outcome PURPOSE To compare long-term cardiovascular morbidity and mortality and their determinants in a population initially treated with one of two endovascular treatment strategies for stenosis or short occlusion of an iliac artery . MATERIAL S AND METHODS A total of 279 symptomatic patients with stenosis or short ( < or = 5-cm ) occlusion of the iliac arteries were r and omly assigned to undergo either primary stent placement or primary angioplasty followed by selective stent placement ( in case of a residual mean pressure gradient greater than 10 mm Hg at the treated site ) . Follow-up data for all 279 patients were provided by the general practitioners and referring clinicians . Events of interest were arterial interventions , re interventions in the iliac arteries , cardiovascular events ( myocardial infa rct ion , stroke , or extracranial bleeding ) , and death . Regression analysis was performed to identify predictors of reintervention and of cardiovascular morbidity and mortality . RESULTS The mean follow-up period was 5.6 years + /- 1.3 ( + /- st and ard deviation ) . There were no significant differences between primary stent placement and primary angioplasty treatment groups in regard to number of re interventions in the treated iliac arteries ( 33 [ 18 % ] of 187 segments and 33 [ 20 % ] of 169 segments , respectively ) or in the ipsilateral legs ( 45 [ 25 % ] of 181 legs and 50 [ 30 % ] of 164 legs , respectively ) . The risk of other cardiovascular events in primary stent placement and primary angioplasty groups was 13 % ( 18 of 143 ) and 11 % ( 15 of 136 ) , and the risk of death was 15 % ( 21 of 143 patients ) and 16 % ( 22 of 136 patients ) , respectively . Sex , presence of critical ischemia , and length of stenosis were predictors of whether a patient would require iliac reintervention . Myocardial infa rct ion , stroke , and vascular death were predicted on the basis of a patient 's creatinine level and walking distance as tested at the time of inclusion . CONCLUSION No difference was found in the number of re interventions between the two treatment groups 5 years after treatment . Patients with iliac artery disease are at high risk of cardiovascular morbidity and mortality Background Iliac artery atherosclerotic disease may cause intermittent claudication and critical limb ischemia . It can lead to serious complications such as infection , amputation and even death . Revascularization relieves symptoms and prevents these complications . Historically , open surgical repair , in the form of endarterectomy or bypass , was used . Over the last decade , endovascular repair has become the first choice of treatment for iliac arterial occlusive disease . No definitive consensus has emerged about the best endovascular strategy and which type of stent , if any , to use . However , in more advanced disease , that is , long or multiple stenoses or occlusions , literature is most supportive of primary stenting with a balloon-exp and able stent in the common iliac artery ( Jongkind V et al. , J Vasc Surg 52:1376 - 1383,2010 ) . Recently , a PTFE-covered balloon-exp and able stent ( Advanta V12 , Atrium Medical Inc. , Hudson , NH , USA ) has been introduced for the iliac artery . Covering stents with PTFE has been shown to lead to less neo-intimal hyperplasia and this might lower restenosis rates ( Dolmatch B et al. J Vasc Interv Radiol 18:527 - 534,2007 , Marin ML et al. J Vasc Interv Radiol 7:651 - 656,1996 , Virmani R et al. J Vasc Interv Radiol 10:445 - 456,1999 ) . However , only one RCT , of mediocre quality has been published on this stent in the common iliac artery ( Mwipatayi BP et al. J Vasc Surg 54:1561 - 1570,2011 , Bekken JA et al. J Vasc Surg 55:1545 - 1546,2012 ) . Our hypothesis is that covered balloon-exp and able stents lead to better results when compared to uncovered balloon-exp and able stents . Methods / Design This is a prospect i ve , r and omized , controlled , double-blind , multi-center trial . The study population consists of human volunteers aged over 18 years , with symptomatic advanced atherosclerotic disease of the common iliac artery , defined as stenoses longer than 3 cm and occlusions . A total of 174 patients will be included . The control group will undergo endovascular dilatation or revascularization of the common iliac artery , followed by placement of one or more uncovered balloon-exp and able stents . The study group will undergo the same treatment , however one or more PTFE-covered balloon-exp and able stents will be placed . When necessary , the aorta , external iliac artery , common femoral artery , superficial femoral artery and deep femoral artery will be treated , using the st and ard treatment . The primary endpoint is absence of binary restenosis rate . Secondary endpoints are reocclusion rate , target-lesion revascularization rate , clinical success , procedural success , hemodynamic success , major amputation rate , complication rate and mortality rate . Main study parameters are age , gender , relevant co-morbidity , and several patient , disease and procedure-related parameters . Trial registration Dutch Trial Register , NTR3381 Purpose To determine initial technical results of percutaneous transluminal angioplasty ( PTA ) and stent procedures in the iliac artery , mean intraarterial pressure gradients were recorded before and after each procedure . Methods We r and omly assigned 213 patients with typical intermittent claudication to primary stent placement ( n=107 ) or primary PTA ( n=106 ) , with subsequent stenting in the case of a residual mean pressure gradient of > 10 mmHg ( n=45 ) . Eligibility criteria included angiographic iliac artery stenosis ( > 50 % diameter reduction ) and /or a peak systolic velocity ratio > 2.5 on duplex examination . Mean intraarterial pressures were simultaneously recorded above and below the lesion , at rest and also durign vasodilatation in the case of a resting gradient ≤10 mmHg . Results Pressure gradients in the primary stent group were 14.9±10.4 mmHg before and 2.9±3.5 mmHg after stenting . Pressure gradients in the primary PTA group were 17.3±11.3 mmHg pre-PTA , 4.2±5.4 mmHg post-PTA , and 2.5±2.8 mmHg after selective stenting . Compared with primary stent placement , PTA plus selective stent placement avoided application of a stent in 63 % ( 86/137 ) of cases , result ing in a considerable cost saving . Conclusion Technical results of primary stenting and PTA plus selective stenting are similar in terms of residual pressure gradients BACKGROUND Percutaneous transluminal angioplasty ( PTA ) is a safe , simple , and successful treatment for intermittent claudication caused by iliac-artery occlusive disease .  Primary stent placement has been proposed as more effective than PTA . We compared the technical results and clinical outcomes of two treatment strategies- primary placement of a stent across the stenotic segment of the iliac artery , or primary PTA followed by selective stent placement when haemodynamic results were inadequate . METHODS We r and omly assigned 279 patients with intermittent claudication , recruited from departments of vascular surgery , either to direct stent placement ( group I , n=143 ) or primary angioplasty ( group II , n=136 ) , with subsequent stent placement in case of a residual mean pressure gradient greater than 10 mm Hg across the treated site . The main inclusion criterion was intermittent claudication on the basis of iliac-artery stenosis of more than 50 % , proven by angiography . All patients had a clinical assessment before intervention and at 3 , 12 , and 24 months . Clinical success was defined as improvement of at least one clinical category . Secondary endpoints were initial technical results , procedural complications , cumulative patency as assessed by duplex ultrasonography , and quality of life . FINDINGS In group II , selective stent placement was done in 59 ( 43 % ) of the 136 patients . The mean follow-up was 9.3 months ( range 3 - 24 ) . Initial haemodynamic success and complication rates were 119 ( 81 % ) of 149 limbs and 6 ( 4 % ) of 143 limbs ( group I ) versus 103 ( 82 % ) of 126 limbs and 10 ( 7 % ) of 136 limbs ( group II ) , respectively . Clinical success rates at 2 years were 29 ( 78 % ) of 37 patients and 26 ( 77 % ) of 34 patients in groups I and II , respectively ( p=0.6 ) ; however , 43 % and 35 % of the patients , respectively , still had symptoms . Quality of life improved significantly after intervention ( p<0.05 ) but we found no difference between the groups during follow-up . 2-year cumulative patency rates were similar at 71 % versus 70 % ( p=0.2 ) , respectively , as were reintervention rates at 7 % versus 4 % , respectively ( 95 % CI -2 % to 9 % ) . INTERPRETATION There were no substantial differences in technical results and clinical outcomes of the two treatment strategies both at short-term and long-term follow-up . Since angioplasty followed by selective stent placement is less expensive than direct placement of a stent , the former seems to be the treatment of choice for lifestyle-limiting intermittent claudication caused by iliac artery occlusive disease PURPOSE To investigate the consequences of different hemodynamic criteria as indications for stent placement after suboptimal iliac angioplasty . MATERIAL S AND METHODS One hundred thirty-six patients with intermittent claudication , on the basis of atherosclerotic disease of the iliac artery , underwent angioplasty .  Intraarterial systolic and mean pressures were simultaneously recorded above and below the lesion , with and without vasodilation , and before and after percutaneous angioplasty . These data were used to estimate what proportion of the study population would be eligible for stent placement according to different criteria reported in the literature . Subsequently , the authors compared peak systolic velocity ( PSV ) ratios during follow-up in their patients , with and without indication for stent placement according to two different criteria . RESULTS Applying the different thresholds reported in the literature to the patient group shows that stent placement would be indicated in anywhere from 4 % to 87 % of cases . No difference was observed when PSV ratios were compared in patients with a residual mean pressure gradient of > or = 5 and < or = 10 mm Hg with patients with a residual mean pressure gradient of less than 5 mm Hg . CONCL 
    Output:
    
There is insufficient evidence to assess the effects of PTA versus PS for stenotic and occlusive lesions of the iliac artery .
From one study it appears that PS in iliac artery occlusions may result in lower distal embolisation rates .