***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 —Recovery of function is possible in patients with ischemic cardiomyopathy when left ventricular dysfunction is caused by stunning or hibernation . It is plausible that recovery of function after revascularization may take a longer time in hibernating myocardium compared with stunned myocardium . Accordingly , the time courses of functional recovery in hibernating and stunned myocardium were compared . Methods and Results — Patients ( n=26 ) with ischemic cardiomyopathy undergoing surgical revascularization  were studied ; regional perfusion ( resting 201Tl single-photon emission CT ) , glucose utilization ( 18F-2-deoxyglucose single-photon emission CT ) , and contractile function ( 2D echocardiography ) were assessed before revascularization . Dysfunctional segments with normal perfusion/glucose utilization were considered to be stunned , and dysfunctional segments with reduced perfusion/preserved glucose utilization were considered to be hibernating . Contractile function was reevaluated 3 months ( early ) and 14 months ( late ) after revascularization . Of the 266 dysfunctional segments , 57 ( 22 % ) were stunned , 62 ( 23 % ) were hibernating , and 147 ( 55 % ) were scar tissue . In stunned myocardium , contractile function improved significantly at 3 months , without further improvement at 14 months ; 61 % of the stunned segments improved at 3 months , and 9 % improved at 14 months . In hibernating myocardium , contractile function improved at 3 months , with a further improvement at 14 months ; 31 % of the hibernating segments improved at 3 months , and 61 % showed ( additional ) recovery at 14 months . Conclusions —Stunned myocardium is likely to demonstrate early recovery of function , whereas hibernating myocardium may take a longer time to ( fully ) recover in function after revascularization Background —Low-dose dobutamine challenge ( DSMR ) by MRI was compared with delayed enhancement imaging with Gd-DTPA ( SCAR ) as a predictor of improvement of wall motion after revascularization ( RECOVERY ) . Methods and Results —In 29 patients with coronary artery disease ( 68±7 years of age , 2 women , 32±8 % ejection fraction ) , wall motion was evaluated semiquantitatively by MRI before and 3 months after revascularization .  SCAR and DSMR were performed before revascularization . The transmural extent of scar was assessed semiquantitatively . Binary prediction of RECOVERY was performed by logistic regression in 288 segments with wall motion abnormalities at rest . Receiver operating characteristic – area under curve ( AUC ) statistics were used to compare different models . Low-dose DSMR ( AUC 0.838 ) was superior to SCAR ( AUC 0.728 ) in predicting RECOVERY . SCAR did not improve accuracy of prediction by DSMR . Subgroup analysis showed superiority of DSMR for 1 % to 74 % transmural extent of infa rct ion . Conclusions —Low-dose DSMR is superior to SCAR in predicting RECOVERY . This advantage is largest in segments with a delayed enhancement of 1 % to 74 % OBJECTIVES To assess the acceptability and feasibility of functional tests as a gateway to angiography for management of coronary artery disease ( CAD ) , the ability of diagnostic strategies to identify patients who should undergo revascularisation , patient outcomes in each diagnostic strategy , and the most cost-effective diagnostic strategy for patients with suspected or known CAD . DESIGN A rapid systematic review of economic evaluations of alternative diagnostic strategies for CAD was carried out . A pragmatic and generalisable r and omised controlled trial was undertaken to assess the use of the functional cardiac tests : angiography ( controls ) ; single photon emission computed tomography ( SPECT ) ; magnetic resonance imaging ( MRI ) ; stress echocardiography . SETTING The setting was Papworth Hospital NHS Foundation Trust , a tertiary cardiothoracic referral centre . PARTICIPANTS Patients with suspected or known CAD and an exercise test result that required non-urgent angiography . INTERVENTIONS Patients were r and omised to one of the four initial diagnostic tests . MAIN OUTCOME MEASURES Eighteen months post-r and omisation : exercise time ( modified Bruce protocol ) ; cost-effectiveness compared with angiography ( diagnosis , treatment and follow-up costs ) . The aim was to demonstrate equivalence in exercise time between those r and omised to functional tests and those r and omised to angiography [ defined as the confidence interval ( CI ) for mean difference from angiography within 1 minute ] . RESULTS The 898 patients were r and omised to  angiography  ( n = 222 ) , SPECT ( n = 224 ) , MRI ( n = 226 ) or stress echo ( n = 226 ) . Initial diagnostic tests were completed successfully with unequivocal results for 98 % of angiography , 94 % of SPECT ( p = 0.05 ) , 78 % of MRI ( p < 0.001 ) and 90 % of stress echocardiography patients ( p < 0.001 ) . Some 22 % of SPECT patients , 20 % of MRI patients and 25 % of stress echo patients were not subsequently referred for an angiogram . Positive functional tests were confirmed by positive angiography in 83 % of SPECT patients , 89 % of MRI patients and 84 % of stress echo patients . Negative functional tests were followed by positive angiograms in 31 % of SPECT patients , 52 % of MRI patients and 48 % of stress echo patients tested . The proportions that had coronary artery bypass graft surgery were 10 % ( angiography ) , 11 % ( MRI ) and 13 % ( SPECT and stress echo ) and percutaneous coronary intervention 25 % ( angiography ) , 18 % ( SPECT ) and 23 % ( MRI and stress echo ) . At 18 months , comparing SPECT and stress echo with angiography , a clinical ly significant difference in total exercise time can be ruled out . The MRI group had significantly shorter mean total exercise time of 35 seconds and the upper limit of the CI was 1.14 minutes less than in the angiography group , so a difference of at least 1 minute can not be ruled out . At 6 months post-treatment , SPECT and angiography had equivalent mean exercise time . Compared with angiography , the MRI and stress echo groups had significantly shorter mean total exercise time of 37 and 38 seconds , respectively , and the upper limit of both CIs was 1.16 minutes , so a difference of at least 1 minute can not be ruled out . The differences were mainly attributable to revascularised patients . There were significantly more non-fatal adverse events in the stress echo group , mostly admissions for chest pain , but no significant difference in the number of patients reporting events . Mean ( 95 % CI ) total additional costs over 18 months , compared with angiography , were 415 pounds ( -310 pounds to 1084 pounds ) for SPECT , 426 pounds ( -247 pounds to 1088 pounds ) for MRI and 821 pounds ( 10 pounds to 1715 pounds ) for stress echocardiography , with very little difference in quality -adjusted life-years ( QALYs ) amongst the groups ( less than 0.04 QALYs over 18 months ) . Cost-effectiveness was mainly influenced by test costs , clinicians ' willingness to trust negative functional tests and by a small number of patients who had a particularly difficult clinical course . CONCLUSIONS Between 20 and 25 % of patients can avoid invasive testing using functional testing as a gateway to angiography , without substantial effects on outcomes . The SPECT strategy was as useful as angiography in identifying patients who should undergo revascularisation and the additional cost was not significant , in fact it would be reduced further by restricting the rest test to patients who have a positive stress test . MRI had the largest number of test failures and , in this study , had the least practical use in screening patients with suspected CAD , although it had similar outcomes to stress echo and is still an evolving technology . Stress echo patients had a 10 % test failure rate , significantly shorter total exercise time and time to angina at 6 months post-treatment , and a greater number of adverse events , leading to significantly higher costs . Given the level of skill required for stress echo , it may be best to reserve this test for those who have a contraindication to SPECT and are unable or unwilling to have MRI . Further research , using blinded re assessment of functional test results and angiograms , is required to formally assess diagnostic accuracy . Longer-term cost-effectiveness analysis , and further studies of MRI and new generation computed tomography are also required Background Monitoring contrast medium wash-in kinetics in hyperemic myocardium by magnetic resonance ( MR ) allows for the detection of stenosed coronary arteries . In this prospect i ve study , the quality of a multislice MR approach with respect to the detection and sizing of compromised myocardium was determined and compared with positron emission tomography ( PET ) and quantitative coronary angiography . Methods and Results A total of 48 patients and 18 healthy subjects were studied by MR using a multislice hybrid echo-planar pulse sequence for monitoring the myocardial first pass kinetics of gadolinium-diethylenetriamine pentaacetic acid bismethylamide ( Omniscan ; 0.1 mmol/kg injected at 3 mL/s IV ) during hyperemia ( dipyridamole 0.56 mg/kg ) . Signal intensity upslope as a measure of myocardial perfusion was calculated in 32 sectors per heart from pixelwise parametric maps in the subendocardial layer and for full wall thickness . Before coronary angiography , coronary flow reserve ( hyperemia induced by dipyridamole 0.56 mg/kg ) was determined in corresponding sectors by 13N-ammonia PET . Receiver-operator characteristic analysis of subendocardial upslope data revealed a sensitivity and specificity of 91 % and 94 % , respectively , for the detection of coronary artery disease as defined by PET ( mean coronary flow reserve minus 2SD of controls ) and a sensitivity and specificity of 87 % and 85 % , respectively , in comparison with quantitative coronary angiography ( diameter stenosis ≥50 % ) . The number of pathological sectors per patient on PET and MR studies correlated linearly ( slope , 0.94;r = 0.76;P < 0.0001 ) . Conclusions The presented MR approach reliably identifies patients with coronary artery stenoses and provides information on the amount of compromised myocardium , even when perfusion abnormalities are confined to the subendocardial layer . This modality may qualify for its clinical application in the management of coronary artery disease Background — Although impairment in perfusion reserve is well recognized in hibernating myocardium , there is substantial controversy as to whether resting myocardial blood flow ( MBF ) is reduced in such circumstances . Quantitative first-pass cardiovascular magnetic resonance ( CMR ) perfusion imaging allows absolute quantification of MBF . We hypothesized that MBF assessed at rest by quantitative CMR perfusion imaging is reduced in hibernating myocardium . Methods and Results — Twenty-seven patients with 1 or 2-vessel coronary disease and at least 1 dysfunctional myocardial segment undergoing PCI  were studied with preprocedure , early ( 24 hours ) , and late ( 9 months ) postprocedure CMR imaging . First-pass perfusion images at rest were acquired in 3 short-axis planes by use of a T1-weighted turboFLASH sequence . In each slice , MBF was determined for 8 myocardial segments in mL · min−1 · g−1 by deconvolution of signal intensity curves with an arterial input function measured in the left ventricular blood pool . Cine MRI for assessment of global and segmental function and delayed enhancement MRI for detection of viability were also obtained . All coronary lesions were 80 % to 95 % stenosis in severity . Over all segments , mean MBF normalized by rate-pressure product ( “ corrected MBF ” ) was 1.2±0.3 mL · min−1 · g−1 · ( mm Hg · bpm/104)−1 in segments without significant coronary stenosis and 0.7±0.2 mL · min−1 · g−1 · ( mm Hg · bpm/104)−1 in segments with coronary stenosis before PCI ( mixed model controlling for slice and segment z=−23.9 , P<0.001 ) . Early after the procedure , the MBF was 1.2±0.2 mL · min−1 · g−1 · ( mm Hg · bpm/104)−1 in revascularized segments and 1.3±0.2 mL · min−1 · g−1 · ( mm Hg · bpm/104)−1 in nondiseased segments ( z=−6.1 , P<0.001 ) . Late after PCI , the systolic wall thickening and end-diastolic wall thickness both increased significantly more ( both P<0.001 ) in the myocardial segments subtended by severe coronary stenosis ( 8±17 % to 40±19 % and 6.5±1.1 to 9.3±2 mm , respectively ) than in the myocardial segments supplied by nondiseased vessels . Mean MBF in dysfunctional segments with significantly improved contraction after revascularization was 0.8±0.2 mL · min−1 · g−1 · ( mm Hg · bpm/104)−1 before PCI and 1.2±0.2 mL · min−1 · g−1 · ( mm Hg · bpm/10 
    Output:
    
All currently used diagnostic strategies were cost-effective compared with no testing at current National Institute for Health and Care Excellence thresholds .
All the diagnostic pathways are a cost-effective use of NHS re sources .
The cost-effectiveness analyses suggest that CE CMR and revascularising everyone were the optimal strategies .