***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 In patients with coronary artery disease who receive metallic drug-eluting coronary stents , adverse events such as late target-lesion failure may be related in part to the persistent presence of the metallic stent frame in the coronary-vessel wall . Bioresorbable vascular scaffolds have been developed to attempt to improve long-term outcomes . METHODS In this large , multicenter , r and omized trial , 2008 patients with stable or unstable angina were r and omly assigned in a 2:1 ratio to receive an everolimus-eluting bioresorbable vascular ( Absorb ) scaffold ( 1322 patients ) or an everolimus-eluting cobalt-chromium ( Xience ) stent ( 686 patients ) . The primary end point , which was tested for both noninferiority ( margin , 4.5 percentage points for the risk difference ) and superiority , was target-lesion failure ( cardiac death , target-vessel myocardial infa rct ion , or ischemia-driven target-lesion revascularization ) at 1 year . RESULTS Target-lesion failure at 1 year occurred in 7.8 % of patients in the Absorb group and in 6.1 % of patients in the Xience group ( difference , 1.7 percentage points ; 95 % confidence interval , -0.5 to 3.9 ; P=0.007 for noninferiority and P=0.16 for superiority ) . There was no significant difference between the Absorb group and the Xience group in rates of cardiac death ( 0.6 % and 0.1 % , respectively ; P=0.29 ) , target-vessel myocardial infa rct ion ( 6.0 % and 4.6 % , respectively ; P=0.18 ) , or ischemia-driven target-lesion revascularization ( 3.0 % and 2.5 % , respectively ; P=0.50 ) . Device thrombosis within 1 year occurred in 1.5 % of patients in the Absorb group and in 0.7 % of patients in the Xience group ( P=0.13 ) . CONCLUSIONS In this large-scale , r and omized trial , treatment of noncomplex obstructive coronary artery disease with an everolimus-eluting bioresorbable vascular scaffold , as compared with an everolimus-eluting cobalt-chromium stent , was within the prespecified margin for noninferiority with respect to target-lesion failure at 1 year . ( Funded by Abbott Vascular ; ABSORB III Clinical Trials.gov number , NCT01751906 . ) Mixed treatment comparison ( MTC ) meta- analysis is a generalization of st and ard pairwise meta- analysis for A vs B trials , to data structures that include , for example , A vs B , B vs C , and A vs C trials . There are two roles for MTC : one is to strengthen inference concerning the relative efficacy of two treatments , by including both ' direct ' and ' indirect ' comparisons . The other is to facilitate simultaneous inference regarding all treatments , in order for example to select the best treatment . In this paper , we present a range of Bayesian hierarchical models using the Markov chain Monte Carlo software WinBUGS . These are multivariate r and om effects models that allow for variation in true treatment effects across trials . We consider models where the between-trials variance is homogeneous across treatment comparisons as well as heterogeneous variance models . We also compare models with fixed ( unconstrained ) baseline study effects with models with r and om baselines drawn from a common distribution . These models are applied to an illustrative data set and posterior parameter distributions are compared . We discuss model critique and model selection , illustrating the role of Bayesian deviance analysis , and node-based model criticism . The assumptions underlying the MTC models and their parameterization are also discussed OBJECTIVES This study sought to perform clinical and imaging assessment s of the DESolve Bioresorbable Coronary Scaffold ( BCS ) . BACKGROUND BCS , which is drug eluting , may have potential advantages compared with conventional metallic drug-eluting stents . The DESolve system , design ed to provide vessel support and neointimal suppression , combines a poly-l-lactic acid-based scaffold with the antiproliferative myolimus . METHODS The DESolve First-in-Man ( a non-r and omized , consecutive enrollment evaluation of the DESolve myolimus eluting bioresorbable coronary stent in the treatment of patients with de novo native coronary artery lesions ) trial was a prospect i ve multicenter study enrolling 16 patients eligible for treatment . The principal safety endpoint was a composite of cardiac death , myocardial infa rct ion , and clinical ly indicated target lesion revascularization . The principal imaging endpoint was in-scaffold late lumen loss ( LLL ) assessed by quantitative coronary angiography ( QCA ) at 6 months . Intravascular ultrasound ( IVUS ) and optical coherence tomography ( OCT ) imaging was performed at baseline and 6 months ; multislice computed tomography ( MSCT ) was performed at 12 months . RESULTS Acute procedural success was achieved in 15 of 15 patients receiving a study scaffold . At 12 months , there was no scaffold thrombosis and no major adverse cardiac events directly attributable to the scaffold . At 6 months , in-scaffold LLL ( by QCA ) was 0.19 ± 0.19 mm ; neointimal volume ( by IVUS ) was 7.19 ± 3.56 % , with no evidence of scaffold recoil or late malapposition . Findings were confirmed with OCT and showed uniform , thin neointimal coverage ( 0.12 ± 0.04 mm ) . At 12 months , MSCT demonstrated excellent vessel patency . CONCLUSIONS This study demonstrated the feasibility and efficacy of the DESolve BCS . Results showing low in-scaffold LLL , low % neointimal volume at 6 months , no chronic recoil , and maintenance of lumen patency at 12 months prompt further study . ( DESolve First-in-Man ; EudraCT number 2011 - 000027 - 32 ) AIMS To analyse the vasoreactivity of a coronary segment , previously scaffolded by the ABSORB bioresorbable vascular scaffold ( BVS ) device , in relationship to its intravascular ultrasound-virtual histology ( IVUS-VH ) composition and reduction in greyscale echogenicity of the struts . Coronary segments , transiently scaffolded by a polymeric device , may in the long-term recover a normal vasomotor tone . Recovery of a normal endothelial-dependent vasomotion may be enabled by scaffold bioresorption , composition of the underlying tissue , or a combination of both mechanisms . METHODS AND RESULTS All patients from the ABSORB Cohort A and B trials , who underwent a vasomotion test and IVUS-VH investigation at 12 and 24 months , were included .  Acetylcholine ( Ach ) and nitroglycerin were used to test either the endothelial-dependent or -independent vasomotion of the treated segment . Changes in polymeric strut echogenicity-a surrogate for bioresorption-IVUS-VH composition of the tissue underneath the scaffold and their relationship with the pharmacologically induced vasomotion were all evaluated . Overall , 26 patients underwent the vasomotion test ( 18 at 12 and 8 at 24 months ) .  Vasodilatory response to Ach was quantitatively associated with larger reductions over time in polymeric strut echogenicity ( y= -0.159x- 6.85 ; r= -0.781 , P < 0.001 ) . Scaffolded segments with vasoconstriction to Ach had larger vessel areas ( 14.37 ± 2.50 vs. 11.85 ± 2.54 mm(2 ) , P= 0.030 ) , larger plaque burden ( 57.31 ± 5.96 vs. 49.09 ± 9.10 % , P= 0.018 ) , and larger necrotic core ( NC ) areas [ 1.39 ( + 1.14 , + 1.74 ) vs. 0.78 mm(2 ) ( + 0.20 , + 0.98 ) , P= 0.006 ] compared with those with vasodilation . CONCLUSION Vasodilatory response to Ach , in coronary segments scaffolded by the ABSORB BVS device , is associated with a reduction in echogenicity of the scaffold over time , and a low amount of NC . In particular , the latter finding resembles the behaviour of a native coronary artery not caged by an intracoronary device OBJECTIVES Using intravascular ultrasound ( IVUS ) and histomorphometry , this study sought to evaluate the potential of nonatherosclerotic porcine coronary arteries to undergo progressive lumen gain and a return of pulsatility after implantation with an everolimus-eluting bioresorbable vascular scaffold ( BVS ) . BACKGROUND Unique benefits such as lumen gain and restored vasomotion have been demonstrated clinical ly after treatment with BVS ; however , a more rigorous demonstration of these benefits with a r and omized clinical trial has not yet been conducted . METHODS Seventy nonatherosclerotic swine received 109 everolimus-eluting BVS and 70 everolimus-eluting metal stents r and omized among the main coronary arteries . Arteries were evaluated in vivo by angiography and IVUS and post-mortem by histomorphometry at time points from 1 to 42 months . RESULTS From 1 to 6 months , both BVS- and everolimus-eluting metal stent-implanted arteries demonstrated stable lumen areas ( LAs ) . From 12 months to 42 months , there was a progressive increase in the LA of arteries implanted with a BVS as assessed by histomorphometry and IVUS . This lumen gain in the implanted segment corresponded to an increase in the reference vessel LA . Normalization in the in-segment LA ( LA : reference vessel LA ) was observed qualitatively by angiography and quantitatively by IVUS . Additionally , BVS-implanted arteries demonstrated restored in-segment pulsatility on the basis of IVUS assessment of the differences in the mid-scaffold area between end-diastole to end-systole . CONCLUSIONS Starting at 12 months , BVS-implanted porcine coronary arteries underwent progressive lumen gain and showed restored pulsatility . These benefits demonstrated pre clinical ly may translate into improvements in long-term clinical outcomes for patients treated with BVS compared with conventional drug-eluting stents AIMS To compare the long-term clinical safety between two drug-eluting stents with different healing characteristics in the Patient Related Outcomes with  Endeavour ( E-ZES ) vs. Cypher ( C-SES ) Stenting Trial ( PROTECT ) . At 3 years , there was no difference in the primary outcome of definite or probable stent thrombosis or in the other main secondary clinical outcomes consisting of the composite of death or myocardial infa rct ion ( MI ) . Prespecified 4-year clinical follow-up was analysed . METHODS AND RESULTS Patient Related OuTcomes with Endeavour vs. Cypher Stenting Trial was a prospect i ve , open-label r and omized-controlled superiority trial powered to look at differences in long-term clinical safety , including stent thrombosis .  Dual antiplatelet therapy ( DAPT ) was prescribed for ≥ 3 months and up to 12 months based on current guidelines . Patient Related OuTcomes with Endeavour vs. Cypher Stenting Trial enrolled 8791 patients undergoing elective or emergency PCI to E-ZES or C-SES . There was no difference in DAPT usage between the two groups up to 4 years . At 4-year follow-up , the primary outcome occurred in 1.6 % of E-ZES vs. 2.6 % of C-SES patients [ HR 0.63 ( 95 % CI 0.46 - 0.85 ) , P = 0.003 ] . The composite of all-cause death or large MI occurred in 6.7 % of E-ZES vs. 8.0 % of C-SES-treated patients [ HR 0.84 ( 95 % CI 0.71 - 0.98 ) , P = 0.024 ] . CONCLUSIONS Drug-eluting coronary stents with different healing characteristics demonstrated different late safety profiles : after 4 years , compared with C-SES , E-ZES reduced the risk of stent thrombosis and the risk of the composite endpoints of death or MI . Appropriately powered large-scale trials with long-term follow-up are critical to determine clinical safety and efficacy of permanently implanted coronary stents . This trial is registered with Clinical Trials.gov , number NCT00476957 BACKGROUND Patients at high risk for bleeding who undergo percutaneous coronary intervention ( PCI ) often receive bare-metal stents followed by 1 month of dual antiplatelet therapy . We studied a polymer-free and carrier-free drug-coated stent that transfers umirolimus ( also known as biolimus A9 ) , a highly lipophilic sirolimus analogue , into the vessel wall over a period of 1 month . METHODS In a r and omized , double-blind trial , we compared the drug-coated stent with a very similar bare-metal stent in patients with a high risk of bleeding who underwent PCI .  All patients received 1 month of dual antiplatelet therapy . The primary safety end point , tested for both nonin 
    Output:
    
All contemporary DES were superior to BMS and PES in terms of definite or probable stent thrombosis at 1 year .
CoCr-EES , PtCr-EES , and H-SES were associated with significantly lower risk than BVS .
CoCr-EES and H-SES were superior to SES and BP-BES .
The risk of myocardial infa rct ion was significantly lower with H-SES than with BVS .
There were no significant differences regarding all-cause or cardiac mortality .
Contemporary devices including BVS showed comparably low risks of repeat revascularization .
CONCLUSIONS Contemporary DES , including biocompatible DP-DES , BP-DES , and polymer-free DES , showed a low risk of definite or probable stent thrombosis at 1 year .
BVS had an increased risk of device thrombosis compared with CoCr-EES , PtCr-EES , and H-SES .