***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 Recently concluded multicenter studies have shown that none of an array of echocardiographic indicators of ventricular dyssynchrony have enough sensitivity and specificity for predicting response to cardiac resynchronization therapy ( CRT ) . Inotropic contractile reserve ( ICR ) on dobutamine stress echocardiography can differentiate viable myocardium from scar and is a predictor of improvement in regional and global left ventricular function in patients with cardiomyopathy . Its role in patients undergoing CRT is unknown . The aim of this study was to evaluate the role of ICR in predicting response to CRT in patients with markedly remodeled left ventricles . METHODS Fifty-four patients ( mean age , 69±11 years ; 63 % men ) referred for clinical ly indicated CRT were evaluated . All patients underwent low-dose dobutamine stress echocardiography to assess for ICR , defined as an improvement in contractility in more than five of 16 left ventricular segments . RESULTS During a mean follow-up period of 206±167 days , 31 patients ( 57 % ) were responders , as defined by a 5-point increase in ejection fraction after CRT . The presence of ICR was a stronger predictor of response to CRT ( area under the curve , 0.94 ; χ2=39.0 ; P<.0001 ) compared with dyssynchrony ( area under the curve , 0.74 ; χ2=10.07 ; P=.002 ) . It was a significant predictor of response ( odds ratio , 2.84 ; 95 % confidence interval , 1.59 to 5.09 ; P<.0001 ) , even after controlling for the other predictors , and provided incremental prognostic value beyond that provided by QRS duration and dyssynchrony ( increase in area under the curve from 0.47 to 0.75 to 0.93 ; P=.030 and P=.008 ) . CONCLUSIONS In patients referred for CRT , ICR was a stronger predictor of response and provided incremental value beyond that of current known predictors of response to CRT ( dyssynchrony and QRS duration ) . Dobutamine stress echocardiography may have an important role in identifying CRT responders , and further multicenter studies are needed to confirm this BACKGROUND The assessment of myocardial viability has been used to identify patients with coronary artery disease and left ventricular dysfunction in whom coronary-artery bypass grafting ( CABG ) will provide a survival benefit . However , the efficacy of this approach is uncertain . METHODS In a sub study of patients with coronary artery disease and left ventricular dysfunction who were enrolled in a r and omized trial of medical therapy with or without CABG  , we used single-photon-emission computed tomography ( SPECT ) , dobutamine echocardiography , or both to assess myocardial viability on the basis of prespecified thresholds . RESULTS Among the 1212 patients enrolled in the r and omized trial , 601 underwent assessment of myocardial viability . Of these patients , we r and omly assigned 298 to receive medical therapy plus CABG and 303 to receive medical therapy alone . A total of 178 of 487 patients with viable myocardium ( 37 % ) and 58 of 114 patients without viable myocardium ( 51 % ) died ( hazard ratio for death among patients with viable myocardium , 0.64 ; 95 % confidence interval [ CI ] , 0.48 to 0.86 ; P=0.003 ) . However , after adjustment for other baseline variables , this association with mortality was not significant ( P=0.21 ) . There was no significant interaction between viability status and treatment assignment with respect to mortality ( P=0.53 ) . CONCLUSIONS The presence of viable myocardium was associated with a greater likelihood of survival in patients with coronary artery disease and left ventricular dysfunction , but this relationship was not significant after adjustment for other baseline variables . The assessment of myocardial viability did not identify patients with a differential survival benefit from CABG , as compared with medical therapy alone . ( Funded by the National Heart , Lung , and Blood Institute ; STICH Clinical Trials.gov number , NCT00023595 . ) AIMS Contradicting reports have been published regarding the relation between a dobutamine-induced increase in either cardiac dyssynchrony or left-ventricular ejection fraction ( LVEF ) and the response to cardiac resynchronization therapy ( CRT ) . Using  apical rocking ( ApRock ) as surrogate dyssynchrony parameter , we investigated the dobutamine stress echocardiography (DSE)-induced changes in left-ventricular ( LV ) dyssynchrony and LVEF and their potential pathophysiological interdependence . METHODS AND RESULTS Fifty-eight guideline -selected CRT c and i date s were prospect ively enrolled for low-dose DSE . Dyssynchrony was quantified by the amplitude of ApRock . An LVEF increase during stress of > 5 % was regarded significant . Scar burden was assessed by magnetic resonance imaging . Mean follow-up after CRT implantation was 41 ± 13 months for the occurrence of cardiac death . ApRock during DSE predicted CRT response ( AUC 0.88 , 95 % CI 0.77 - 0.99 , P < 0.001 ) and correlated inversely with changes in EF ( r = -0.6 , P < 0.001 ) . Left-ventricular ejection fraction changes during DSE were not associated with CRT response ( P = 0.082 ) . Linear regression analysis revealed an inverse association of LVEF changes during DSE with both , total scar burden ( B = -2.67 , 95CI -3.77 to -1.56 , P < 0.001 ) and the DSE-induced change in ApRock amplitude ( B = -1.23 , 95 % CI -1.53 to -0.94 , P < 0.001 ) . Kaplan-Meier analysis revealed that DSE-induced increase in ApRock , but not LVEF , was associated with improved long-term survival . CONCLUSION During low-dose DSE in CRT c and i date s with baseline dyssynchrony , myocardial contractile reserve predominantly results in more dyssynchrony , but less in an increase in LVEF . Dyssynchrony at baseline and its dobutamine-induced changes are predictive of both response and long-term survival following CRT BACKGROUND Cardiac resynchronization therapy ( CRT ) is effective in patients with heart failure , but 30 % to 50 % of subjects are classified as nonresponders . Identifying responders remains a challenging task . AIMS The LODO-CRT trial investigated the association between left ventricular contractile reserve ( LVCR ) and clinical and echocardiographic long-term CRT response . METHODS This is a multicenter , prospect i ve , observational study . Left ventricular contractile reserve was detected using a dobutamine stress echocardiography test , defined as an ejection fraction increase of > 5 points . Clinical CRT response was defined as the absence of major cardiovascular events ( ie , cardiovascular death or heart failure hospitalization ) . Echocardiographic response was defined as a left ventricle end-systolic volume reduction of > 10 % . RESULTS A total of 221 CRT-indicated patients were studied ( 80 % presented LVCR ) . During a mean follow-up of 15 ± 5 months , 17 patients died and 16 were hospitalized due to heart failure . The proportion of clinical responders was 155 ( 88 % ) of 177 and 33 ( 75 % ) of 44 ( P = .036 ) in the groups with and without LVCR , respectively . Kaplan-Meier analysis showed a significant difference in cardiac survival/hospitalization between patients with and without LVCR . The proportion of echocardiographic responders was 144 ( 87 % ) of 166 and 16 ( 42 % ) of 38 in the groups with and without LVCR ( P < .001 ) , respectively ; LVCR showed 90 % sensitivity and 87 % positive predictive value to prefigure echocardiographic CRT responders . Multivariable analysis identified LVCR and interventricular dyssynchrony as independent predictors of CRT response . The concomitant presence of both factors showed 99 % specificity and 83 % sensitivity in detecting responders . CONCLUSION The presence of LVCR helps in predicting a clinical and echocardiographic CRT response . Concomitant assessment of LVCR and interventricular dyssynchrony accurately stratifies responder and nonresponder patients Background Stress echocardiography ( SE ) has an established role in evidence -based guidelines , but recently its breadth and variety of applications have extended well beyond coronary artery disease ( CAD ) . We lack a prospect i ve research study of SE applications , in and beyond CAD , also considering a variety of signs in addition to regional wall motion abnormalities . Methods In a prospect i ve , multicenter , international , observational study design , > 100 certified high-volume SE labs ( initially from Italy , Brazil , Hungary , and Serbia ) will be networked with an organized system of clinical , laboratory and imaging data collection at the time of physical or pharmacological SE , with structured follow-up information . The study is endorsed by the Italian Society of Cardiovascular Echography and organized in 10 subprojects focusing on : contractile reserve for prediction of cardiac resynchronization or medical therapy response ; stress B-lines in heart failure ; hypertrophic cardiomyopathy ; heart failure with preserved ejection fraction ; mitral regurgitation after either transcatheter or surgical aortic valve replacement ; outdoor SE in extreme physiology ; right ventricular contractile reserve in repaired Tetralogy of Fallot ; suspected or initial pulmonary arterial hypertension ; coronary flow velocity , left ventricular elastance reserve and B-lines in known or suspected CAD ; identification of sub clinical familial disease in genotype-positive , phenotype- negative healthy relatives of inherited disease ( such as hypertrophic cardiomyopathy ) . Results We expect to recruit about 10,000 patients over a 5-year period ( 2016 - 2020 ) , with sample sizes ranging from 5,000 for coronary flow velocity/ left ventricular elastance/ B-lines in CAD to around 250 for hypertrophic cardiomyopathy or repaired Tetralogy of Fallot . This data -base will allow to investigate technical questions such as feasibility and reproducibility of various SE parameters and to assess their prognostic value in different clinical scenarios . Conclusions The study will create the cultural , informatic and scientific infrastructure connecting high-volume , accredited SE labs , sharing common criteria of indication , execution , reporting and image storage of SE to obtain original safety , feasibility , and outcome data in evidence -poor diagnostic fields , also outside the established core application of SE in CAD based on regional wall motion abnormalities . The study will st and ardize procedures , vali date emerging signs , and integrate the new information with established knowledge , helping to build a next-generation SE lab without inner walls Background —In some patients with heart failure , & bgr;-blockers can improve left ventricular ( LV ) function and reduce morbidity and mortality . We hypothesized that gadolinium-enhanced cardiovascular magnetic resonance imaging ( CMR ) can predict reversible myocardial dysfunction and remodeling in heart failure patients treated with & bgr;-blockers .  Methods and Results —Forty-five patients with chronic heart failure underwent CMR .  Contrast imaging using gadolinium was performed to obtain high-resolution spatial maps of myocardial scarring and viability . Cine imaging was performed to assess LV function and morphology and was repeated in 35 patients after 6 months of & bgr;-blockade . Gadolinium CMR demonstrated scarring in 30 of 45 patients ( 67 % ) . Scarring was found in 100 % of patients with ischemic cardiomyopathy ( 28 of 28 ) but in only 12 % with nonischemic cardiomyopathy ( 2 of 17 ) . In the 35 patients who were maintained on & bgr;-blockers  and had a second study , there was an inverse relation between the extent of scarring at baseline and the likelihood of contractile improvement 6 months later ( P < 0.001 ) . For instance , contractility improved in 56 % ( 674 of 1207 ) of regions with no scarring but in only 3 % with > 75 % scarring ( 8 of 232 ) . Multivariate analysis showed that the amount of dysfunctional but viable myocardium by CMR was an independent predictor of the change in ejection fraction ( P = 0.01 ) , mean wall motion score ( P = 0.0007 ) , LV end-diastolic volume index ( P = 0.007 ) , and LV end-systolic volume index ( P ≤0.0001 ) . Conclusions —For heart failure patients treated with & bgr;-blockers  , gadolinium-enhanced CMR predicts the response in LV function and remodeling OBJECTIVE To underst and whether patients with post-ischemic dilated cardiomyopathy and myocardial viability ( MV ) could benefit from cardiac resynchronization therapy ( CRT ) in terms of clinical , echocardiographic and neuro- hormonal parameters compared to patients without MV . METHODS One hundred and four consecutive patients were enrolled in a prospect i ve observational cohort study . Using do 
    Output:
    
Conclusion The presence of LVCR during SE with either dobutamine or exercise is associated with a greater chance of response to CRT .