***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 — The incretin hormone glucagon-like peptide-1 ( GLP-1 ) has been shown to have cardioprotective properties in animal models of ischemia and infa rct ion due to promotion of myocardial glucose uptake and suppression of apoptosis . We investigated whether GLP-1 protected the heart from dysfunction caused by supply ischemia during percutaneous coronary intervention ( PCI ) . Methods and Results — Twenty patients with normal left ventricular ( LV ) function and single-vessel coronary disease within the left anterior descending artery undergoing elective PCI were studied . A conductance catheter was placed into the LV through the femoral artery , and pressure-volume loops were recorded at baseline and during a 1-minute low-pressure balloon occlusion at the site of the stenosis . The patients were r and omized to receive an infusion of either GLP-1(7–36 ) amide at 1.2 pmol/kg per minute or saline immediately after the first balloon occlusion . Coronary balloon occlusion caused LV stunning in the control group with cumulative LV dysfunction on subsequent occlusion that was not seen in the GLP-1 group . GLP-1 improved recovery of LV systolic and diastolic function at 30 minutes after balloon occlusion compared with control ( delta dP/dtmax from baseline , −1.6 % versus −12.2 % ; P=0.02 ) and reduced the LV dysfunction after the second balloon occlusion ( delta dP/dtmax , −13.1 % versus −25.3 % ; P=0.01 ) . Conclusions — In this pilot study , infusion of GLP-1 has been demonstrated to reduce ischemic LV dysfunction after supply ischemia during coronary balloon occlusion in humans and mitigates stunning . The findings require confirmation in a larger scale clinical trial . Clinical Trial Registration — URL : http://www.is rct n.org . Unique identifier : IS RCT N 77442023 BACKGROUND Although poststress myocardial stunning is regarded as a marker for severe coronary artery disease ( CAD ) , no study has yet compared the diagnostic value of poststress stunning with transient ischemic dilation ( TID ) of the left ventricle ( LV ) for detecting multivessel CAD . METHODS AND RESULTS A total of 271 patients with suspected or known CAD underwent adenosine triphosphate ( ATP ) loading and at-rest gated single-photon emission computed tomography . We assessed myocardial perfusion with a 20-segment model , and analyzed the changes in LV volumetric analysis induced by ATP and an automatically derived TID ratio . In 147 patients with multivessel CAD , the prevalence of multi-territorial ischemia was higher , and the post-ATP increase in end-systolic volume ( ESV ) and TID ratio were greater , than in the 124 with insignificant or single-vessel CAD ( P<0.0001 , for all cases ) . The receiver-operating characteristic curves analysis revealed cutoff values for ESV of 5 ml and a TID ratio of 1.11 . Multivariate logistic regression analysis revealed that the combination of a poststress increase in ESV of ≥5 ml and multi-territorial ischemia best identified multivessel CAD , with a sensitivity of 78 % and a specificity of 84 % , whereas the TID ratio was not shown to be an independent predictor . CONCLUSIONS Post-ATP stress myocardial stunning is superior to the TID ratio for detecting multivessel CAD Background Postischemic global and regional left ventricular ( LV ) dysfunction on stressgated single photon emission computed tomography ( SPECT ) imaging is attributed widely to myocardial stunning . We sought to determine the specificity of gated SPECT for the detection of myocardial stunning after ischemic stress . Methods and Results Twenty-seven patients with an ischemic response to stress on dual-isotope exercise SPECT were enrolled prospect ively .  Transthoracic echocardiography was performed just before stress gated SPECT for assessment of regional wall motion and quantitative LV ejection fraction ( LVEF ) . The 17 myocardial segments for each patient were scored for myocardial perfusion by stress gated SPECT , and regional wall motion by stress gated SPECT and echo . Of the 459 myocardial segments , 41 % had perfusion defects , 15 % had stress gated SPECT regional wall motion abnormality , 4.8 % had poststress echo regional wall motion abnormality , and 3.9 % had baseline regional wall motion abnormality . Overall , a stress gated SPECT regional wall motion abnormality had a sensitivity of 100 % and a specificity of 89 % . Among reversible perfusion defects of moderate severity or more , a stress gated SPECT regional wall motion abnormality had a specificity of 41 % and a positive predictive value of 8 % . Stress gated SPECT LVEF was similar to poststress echo LVEF for all patients , but significantly lower in patients with reversible perfusion defects of moderate severity or more . Conclusion Post-stress gated SPECT imaging overestimates global and regional myocardial stunning . Caution should be exercised in interpreting poststress global or regional LV function on stress gated SPECT in scans with reversible ischemia AIMS To prospect ively compare the agreement of left ventricular volumes and ejection fraction by M-mode echocardiography ( echo ) , 2D echo , radionuclide ventriculography and cardiovascular magnetic resonance performed in patients with chronic stable heart failure . It is important to know whether the results of each technique are interchangable , and thereby how the results of large studies in heart failure utilizing one technique can be applied using another . Some studies have compared cardiovascular magnetic resonance with echo or radionuclude ventriculography but few contain patients with heart failure and none have compared these techniques with the current fast breath-hold acquisition cardiovascular magnetic resonance . METHODS AND RESULTS Fifty two patients with chronic stable heart failure taking part in the CHRISTMAS Study , underwent M-mode echo , 2D echo , radionuclude ventriculography and cardiovascular magnetic resonance within 4 weeks . The scans were analysed independently in blinded fashion by a single investigator at three core laboratories . Of the echocardiograms , 86 % had sufficient image quality to obtain left ventricular ejection fraction by M-mode method , but only 69 % by 2D Simpson 's biplane analysis . All 52 patients tolerated the radionuclude ventriculography and cardiovascular magnetic resonance , and all these scans were analysable . The mean left ventricular ejection fraction by M-mode cube method was 39+/-16 % and 29+/-15 % by Teichholz M-mode method . The mean left ventricular ejection fraction by 2D echo Simpson 's biplane was 31+/-10 % , by radionuclude ventriculography was 24+/-9 % and by cardiovascular magnetic resonance was 30+/-11 . All the mean left ventricular ejection fractions by each technique were significantly different from all other techniques ( P<0.001 ) , except for cardiovascular magnetic resonance ejection fraction and 2D echo ejection fraction by Simpson 's rule ( P=0.23 ) . The Bl and -Altman limits of agreement encompassing four st and ard deviations was widest for both cardiovascular magnetic resonance vs cube M-mode echo and cardiovascular magnetic resonance vs Teichholz M-mode echo at 66 % each , and was 58 % for radionuclude ventriculography vs cube M-mode echo , 44 % for cardiovascular magnetic resonance vs Simpson 's 2D echo , 39 % for radionuclide ventriculography vs Simpson 's 2D echo , and smallest at 31 % for cardiovascular magnetic resonance-radionuclide ventriculography . Similarly , the end-diastolic volume and end-systolic volume by 2D echo and cardiovascular magnetic resonance revealed wide limits of agreement ( 52 ml to 216 ml and 11 ml to 188 ml , respectively ) . CONCLUSION These results suggest that ejection fraction measurements by various techniques are not interchangeable . The conclusions and recommendations of research studies in heart failure should therefore be interpreted in the context of locally available techniques . In addition , there are very wide variances in volumes and ejection fraction between techniques , which are most marked in comparisons using echocardiography . This suggests that cardiovascular magnetic resonance is the preferred technique for volume and ejection fraction estimation in heart failure patients , because of its 3D approach for non-symmetric ventricles and superior image quality OBJECTIVES We sought to evaluate the usefulness of a comprehensive assessment of four cardiovascular magnetic resonance imaging (CMR)-derived myocardial viability indexes in the setting of myocardial stunning . BACKGROUND Cardiovascular magnetic resonance imaging allows the simultaneous assessment of several viability indexes . METHODS We studied 40 patients with a first ST-segment elevation myocardial infa rct ion ( MI ) and an open infa rct -related artery . At the first week , using CMR , wall motion ( WM ) , and four viability indexes were determined : wall thickness , WM improvement with low-dose dobutamine , perfusion , and transmural extent of necrosis . We created a comprehensive score based on the presence and the relative power of these viability indexes for predicting normal WM at the sixth month . RESULTS Of 153 dysfunctional segments at the first week , 59 ( 39 % ) exhibited normal WM at the sixth month . According to the odds ratio of viability indexes for predicting normal WM , we developed a five-level predictive score . The proportions of segments showing normal WM at sixth month were as follows ; Level 1 ( 0 indexes ) : 0 of 13 ( 0 % ) ; Level 2 ( normal thickness and /or perfusion ) : 14 of 82 ( 17 % ) ; Level 3 ( dobutamine response ) : 5 of 11 ( 45 % ) ; Level 4 ( non-transmural necrosis ) : 20 of 26 ( 77 % ) ; Level 5 ( non-transmural necrosis and dobutamine response ) : 20 of 21 ( 95 % ) , p < 0.0001 for the trend . These proportions were similar in a matched prospect i ve validation group comprising 16 patients ( 0 % , 18 % , 62 % , 77 % , and 90 % for levels 1 to 5 , respectively , p < 0.0001 for the trend ) . CONCLUSIONS A comprehensive analysis of the four more widely used CMR-derived viability indexes is useful for predicting late systolic function after myocardial infa rct ion Background Reperfusion strategies salvage myocardium at risk in acute myocardial infa rct ion ( MI ) . This clinical study was performed to determine whether areas without evidence of delayed MRI contrast enhancement in MI correspond to viability by means of percent systolic wall thickening ( % SWT ) and enddiastolic wall thickness ( EDWT ) in chronic infa rct ion . Methods Twenty MRI studies were performed in ten patients within 6 days of MI and 3 months post-MI . On a segmental basis the percentage of viable myocardium as defined by contrast-enhanced MRI ( no delayed MRI contrast enhancement ) in acute MI was measured and was compared with % SWT and EDWT in chronic MI . Results Of the 1718 segments in acute infa rct ion in which the percentage of viable myocardium was measured 1333 were found to be completely viable by means of contrast-enhanced MRI ( no delayed MRI contrast enhancement ) . All of these segments revealed % SWT on day 90 post-MI , and 97 % of segments were viable by means of an EDWT of more than 5.5 mm . In 85 segments the proportion of viable myocardium was 50–99 % ( mean 56±8 % ) , with 92 % segments found to be viable by means of % SWT and 92 % by EDWT , and of 156 segments with viable myocardium between 1–49 % ( 36±8 % ) 79 % were found to be viable by means of % SWT and 82 % by EDWT . Corresponding proportions of 144 segments with transmural delayed MRI contrast enhancement in acute MI were 45 % and 17 % . Conclusions In acute reperfused MI viable myocardium as delineated by contrast-enhanced MRI is correlated with clinical parameters of viability . Delayed MRI contrast enhancement resolves nontransmural MI and may become a valuable clinical tool when planning revascularization procedures 
    Output:
    
DE-CMR has a higher sensitivity , whereas LDD-CMR has a higher specificity for the detection of viable stunned myocardium following myocardial infa rct ion .