***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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    ***EXAMPLES*** 
    Input: BACKGROUND The rapid and reliable diagnosis of acute myocardial infa rct ion is a major unmet clinical need . METHODS We conducted a multicenter study to examine the diagnostic accuracy of new , sensitive cardiac troponin assays performed on blood sample s obtained in the emergency department from 718 consecutive patients who presented with symptoms suggestive of acute myocardial infa rct ion . Cardiac troponin levels were determined in a blinded fashion with the use of four sensitive assays ( Abbott-Architect Troponin I , Roche High-Sensitive Troponin T , Roche Troponin I , and Siemens Troponin I Ultra ) and a st and ard assay ( Roche Troponin T ) . The final diagnosis was adjudicated by two independent cardiologists . RESULTS Acute myocardial infa rct ion was the adjudicated final diagnosis in 123 patients ( 17 % ) . The diagnostic accuracy of measurements obtained at presentation , as quantified by the area under the receiver-operating-characteristic curve ( AUC ) , was significantly higher with the four sensitive cardiac troponin assays than with the st and ard assay ( AUC for Abbott-Architect Troponin I , 0.96 ; 95 % confidence interval [ CI ] , 0.94 to 0.98 ; for Roche High-Sensitive Troponin T , 0.96 ; 95 % CI , 0.94 to 0.98 ; for Roche Troponin I , 0.95 ; 95 % CI , 0.92 to 0.97 ; and for Siemens Troponin I Ultra , 0.96 ; 95 % CI , 0.94 to 0.98 ; vs. AUC for the st and ard assay , 0.90 ; 95 % CI , 0.86 to 0.94 ) . Among patients who presented within 3 hours after the onset of chest pain , the AUCs were 0.93 ( 95 % CI , 0.88 to 0.99 ) , 0.92 ( 95 % CI , 0.87 to 0.97 ) , 0.92 ( 95 % CI , 0.86 to 0.99 ) , and 0.94 ( 95 % CI , 0.90 to 0.98 ) for the sensitive assays , respectively , and 0.76 ( 95 % CI , 0.64 to 0.88 ) for the st and ard assay . We did not assess the effect of the sensitive troponin assays on clinical management . CONCLUSIONS The diagnostic performance of sensitive cardiac troponin assays is excellent , and these assays can substantially improve the early diagnosis of acute myocardial infa rct ion , particularly in patients with a recent onset of chest pain . ( Clinical Trials.gov number , NCT00470587 . Objective To analyse whether levels of high-sensitivity cardiac troponin ( hs-cTn ) below their respective 99th percentile can be used as a single parameter to rule out acute myocardial infa rct ion ( AMI  ) at presentation . Design Prospect i ve , multicentre study . Main outcome measures We measured  hs-cTn using four different methods ( hs-cTnT Roche , hs-cTnI Siemens , hs-cTnI Beckman Coulter and hs-cTnI Abbott ) in consecutive patients presenting to the emergency department with acute chest pain . Two independent cardiologists adjudicated the final diagnosis . Patients were followed for death or AMI during a mean period of 24 months . Results Among 2072 consecutive patients with hs-cTnT measurements available , 21.4 % had an adjudicated diagnosis of AMI ( sensitivity 89.6 % , 95 % CI 86.4 % to 92.3 % , negative predictive value ( NPV ) : 96.5 % , 95 % CI 95.4 % to 97.4 % ) . Among 1180 consecutive patients with hs-cTnI Siemens measurements available , 20.0 % had AMI ( sensitivity 94.1 % , 95 % CI 90.3 % to 96.7 % , NPV : 98.0 % , 95 % CI : 96.6 % to 98.9 % ) . Among 1151 consecutive patients with hs-cTnI Beckman Coulter measurements available , 19.7 % had AMI ( sensitivity 92.1 % , 95 % CI 87.8 % to 95.2 % , NPV : 97.5 % , 95 % CI 96.0 % to 98.5 % ) . Among 1567 consecutive patients with hs-cTnI Abbott measurements available , 20.0 % had AMI ( sensitivity 77.2 % , 95 % CI 72.1 % to 81.7 % , NPV : 94.3 % , 95 % CI 92.8 % to 95.5 % ) . Conclusions Normal hs-cTn levels at presentation should not be used as a single parameter to rule out AMI as 6%–23 % of adjudicated AMI cases had normal levels of hs-cTn levels at presentation . Our data highlight the lack of st and ardisation among hs-cTnI assays result ing in substantial differences in sensitivity and NPV at the 99th percentile BACKGROUND Two recent clinical trials showed that adding copeptin to a conventional cardiac troponin assay improved diagnostic performance for patients with chest pain early after symptom onset . We prospect ively tested whether copeptin adds information to that provided by a high-sensitivity cardiac troponin T ( hscTnT ) assay in the early evaluation of patients with suspected acute myocardial infa rct ion , particularly non-ST-segment elevation myocardial infa rct ion ( non-STEMI ) . METHODS We enrolled 503 patients with suspected acute coronary syndrome and onset of chest pain occurring within the previous 12 h.  Copeptin  was measured on presentation , and hscTnT  was measured serially at baseline and after 3 and 6 h. We used ROC curve analysis and likelihood ratio χ² statistics for nested models . Diagnostic sensitivities , specificities , positive predictive values ( PPVs ) , and negative predictive values ( NPVs ) were calculated for admission values of copeptin alone , hscTnT alone , and the combination of both markers . RESULTS For ruling out non-STEMI ( after excluding STEMI ) , an hscTnT concentration < 14 ng/L ( 99th percentile ) plus a copeptin concentration < 14 pmol/L yielded a diagnostic sensitivity of 97.7 % ( 95 % CI , 91.9%-99.7 % ) , an NPV of 99.03 % ( 95 % CI , 96.6%-99.9 % ) , a diagnostic specificity of 55.9 % ( 95 % CI , 50.6%-61.0 % ) , and a PPV of 34.4 % ( 95 % CI , 28.5%-40.7 % ) . ROC curve analysis of the continuous biomarker values on admission demonstrated no added value of using this marker combination for ruling out non-STEMI when hscTnT was used as the st and ard for diagnosing non-STEMI . CONCLUSIONS A strategy using copeptin with hscTnT at prespecified cutoffs improves the ruling out of non-STEMI , compared with using hscTnT alone ; thus , this strategy could help to obviate a prolonged stay in the emergency department BACKGROUND The role of the arginine-vasopressin ( AVP ) system in the response to myocardial ischemia is unclear . Copeptin , the C-terminal part of the AVP prohormone is secreted stoichiometrically with AVP . METHODS A total of 253 consecutive patients with suspected myocardial ischemia referred for rest/ergometry myocardial perfusion single-photon emission computed tomography ( SPECT ) were enrolled . We evaluated the response of copeptin during exercise and determined whether measurement of copeptin may be helpful in the detection of myocardial ischemia . RESULTS Myocardial ischemia on perfusion images was detected in 127 patients ( 50 % ) . Median copeptin levels increased significantly with exercise in patients with ischemia as well as in patients without ischemia ( from 3.8 [ IQR 2.8 - 6.6 ] to 12.3 [ IQR 5.2 - 39.6 ] pmol/l , P<0.001 ; and from 3.6 [ IQR 2.6 - 5.7 ] to 10.8 [ IQR 5.0 - 24.5 ] pmol/l , P<0.001 ) . Median exercise-induced changes in copeptin ( Deltacopeptin ) were similar in both groups ( 7.7 versus 5.1 pmol/l , P=0.150 ) . The area under the ROC curve for the ability of Deltacopeptin to detect myocardial ischemia was 0.552 . CONCLUSIONS Copeptin levels increased threefold with exercise , irrespective of the presence or absence of myocardial ischemia . Therefore , myocardial ischemia does not seem to be a major trigger of the AVP system . Measurement of copeptin does not seem helpful in the detection of exercise-induced myocardial ischemia BACKGROUND High-sensitivity cardiac troponin ( hs-cTn ) assays seem to improve the early diagnosis of acute myocardial infa rct ion ( AMI ) , but it is unknown how to best use them in clinical practice . Our objective was to develop and vali date an algorithm for rapid rule-out and rule-in of AMI . METHODS A prospect i ve multicenter study enrolling 872 unselected patients with acute chest pain presenting to the emergency department .  High-sensitivity cardiac troponin T ( hs-cTnT ) was measured in a blinded fashion at presentation and after 1 hour . The final diagnosis was adjudicated by 2 independent cardiologists . An hs-cTnT algorithm incorporating baseline values as well as absolute changes within the first hour was derived from 436 r and omly selected patients and vali date d in the remaining 436 patients . The primary prognostic end point was death during 30 days of follow-up . RESULTS Acute myocardial infa rct ion was the final diagnosis in 17 % of patients . After applying the hs-cTnT algorithm developed in the derivation cohort to the validation cohort , 259 patients ( 60 % ) could be classified as " rule-out , " 76 patients ( 17 % ) as " rule-in , " and 101 patients ( 23 % ) as in the " observational zone " within 1 hour . Overall , this result ed in a sensitivity and negative predictive value of 100 % for rule-out , a specificity and positive predictive value of 97 % and 84 % , respectively , for rule-in , and a prevalence of AMI of 8 % in the observational zone group . Cumulative 30-day survival was 99.8 % , 98.6 % , and 95.3 % ( P < .001 ) in patients classified as rule-out , observational zone , and rule-in , respectively . CONCLUSIONS Using a simple algorithm incorporating hs-cTnT baseline values and absolute changes within the first hour allowed a safe rule-out as well as an accurate rule-in of AMI within 1 hour in 77 % of unselected patients with acute chest pain . This novel strategy may obviate the need for prolonged monitoring and serial blood sampling in 3 of 4 patients Objective To investigate the diagnostic and prognostic role of heart-type fatty acid-binding protein ( hFABP ) compared with copeptin and in addition to high-sensitivity cardiac troponin T ( hs-cTnT ) in patients with chest pain suspected of acute myocardial infa rct ion ( AMI ) . Design Diagnostic and prognostic performances of hFABP , copeptin and hs-cTnT were evaluated and compared . The final diagnosis was adjudicated by two independent cardiologists . Setting This prospect i ve observational multicentre study took place in four primary and one secondary hospital from April 2006 to September 2009 . Patients We enrolled 1247 consecutive patients with suspected AMI to the emergency department . For analysis , patients were included , if baseline levels for hs-cTnT and hFABP were available ( n=1074 ) , patients with ST-segment elevation myocardial infa rct ion ( STEMI ) were excluded for the diagnostic analysis ( n=43 ) . Interventions Treatment was left to the discretion of the emergency physician . Main outcome measures AMI and mortality . Results 4 % of the patients had STEMI and 16 % of the patients had non-STEMI . Patients with AMI had significantly higher levels of hFABP  at presentation ( p<0.001 ) . Neither the combination with hFABP nor with copeptin increased the diagnostic accuracy of hs-cTnT at admission , quantified by the area under the receiver operating characteristic curve ( AUC ) ( p>0.05 ) . The negative predictive value regarding 90-day , 1-year and 2-year mortality was 100 % ( 99–100 ) , 99 % ( 98–100 ) and 
    Output:
    
Conclusion : Despite substantial between- study heterogeneity , this meta- analysis demonstrates that copeptin significantly improves baseline cTn sensitivity .