***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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    Input: BACKGROUND Heart failure patients with primary prevention implantable cardioverter-defibrillators ( ICD )  may experience an improvement in left ventricular ejection fraction ( LVEF ) over time . However , it is unclear how LVEF improvement affects subsequent risk for mortality and sudden cardiac death . OBJECTIVES This study sought to assess changes in LVEF after ICD implantation and the implication of these changes on subsequent mortality and ICD shocks . METHODS We conducted a prospect i ve cohort study of 538 patients with repeated LVEF assessment s after ICD implantation for primary prevention of sudden cardiac death . The primary endpoint was appropriate ICD shock defined as a shock for ventricular tachyarrhythmias . The secondary endpoint was all-cause mortality . RESULTS Over a mean follow-up of 4.9 years , LVEF decreased in 13.0 % , improved in 40.0 % , and was unchanged in 47.0 % of the patients . In the multivariate Cox models comparing patients with an improved LVEF with those with an unchanged LVEF , the hazard ratios were 0.33 ( 95 % confidence interval : 0.18 to 0.59 ) for mortality and 0.29 ( 95 % confidence interval : 0.11 to 0.78 ) for appropriate shock . During follow-up , 25 % of patients showed an improvement in LVEF to > 35 % and their risk of appropriate shock decreased but was not eliminated . CONCLUSIONS Among primary prevention ICD patients , 40.0 % had an improved LVEF during follow-up and 25 % had LVEF improved to > 35 % . Changes in LVEF were inversely associated with all-cause mortality and appropriate shocks for ventricular tachyarrhythmias . In patients whose follow-up LVEF improved to > 35 % , the risk of an appropriate shock remained but was markedly decreased Background —Heart failure with recovered or improved ejection fraction ( HFiEF ) has been proposed as a new category of HF . Whether HFiEF is clinical ly distinct from HF with persistently reduced ejection fraction remains to be vali date d. Methods and Results —Of the 5010 subjects enrolled in the Valsartan Heart Failure Trial ( Val-HeFT ) , 3519 had a baseline left ventricular EF of < 35 % and a follow-up echocardiographic assessment of EF at 12 months . Of these , 321 ( 9.1 % ) patients who had a 12-month EF of > 40 % constituted the subgroup with HFiEF . EF improved from 28.7±5.6 % to 46.5±5.6 % in the subgroup with HFiEF and remained reduced ( 25.2±6.2 % and 27.5±7.1 % ) in the subgroup with HF with reduced ejection fraction . The group with HFiEF had a less severe hemodynamic , biomarker , and neurohormonal profile , and it was treated with a more intense HF medication regimen . Subjects who had higher blood pressure  and those treated with a & bgr;-blocker or r and omized to valsartan had greater odds of being in the HFiEF group , whereas those with an ischemic pathogenesis , a more dilated left ventricle , and a detectable hs-troponin had lower odds of an improvement in EF . Recovery of the EF to > 40 % was associated with a better survival compared with persistently reduced EF . Conclusions —Our data support HFiEF as a stratum of HF with reduced ejection fraction with a more favorable outcome , which occurs in a minority of patients with HF with reduced ejection fraction who have a lower prevalence of ischemic heart disease , a less severe hemodynamic , biomarker , and neurohormonal profile , and who are treated with a more intense HF medication regimen . Clinical Trial Registration —URL : http://www . clinical trials.gov . Unique identifier : NCT00336336 Objectives The beneficial effects of cardiac resynchronization therapy ( CRT ) are thought to result from favorable left ventricular ( LV ) reverse remodeling , however CRT is only successful in about 70 % of patients . Whether response to CRT is associated with a decrease in ventricular arrhythmias ( VA ) is still discussed controversially . Therefore , we investigated the incidence of VA in CRT responders in comparison with non-responders . Methods In this nonr and omized , two-center , observational study patients with moderate-to-severe heart failure , LV ejection fraction ( LVEF ) ≤35 % , and QRS duration > 120 ms undergoing CRT were included . After 6 months patients were classified as CRT responders or non-responders . Incidence of VA was compared between both groups by Kaplan-Meier analysis and Cox regression analysis . ROC analysis was performed to determine the aptitude of LVEF cut-off values to predict VA . Results In total 126 consecutive patients ( 64±11years ; 67%male ) were included , 74 were classified as responders and 52 as non-responders . While the mean LVEF at baseline was comparable in both groups ( 25±7 % vs. 24±8 % ; P = 0.4583 ) only the responder group showed an improvement of LVEF ( 36±6 % vs. 24±7 ; p<0.0001 ) under CRT . In total in 56 patients VA were observed during a mean follow-up of 28±14 months , with CRT responders experiencing fewer VA than non-responders ( 35 % vs. 58 % , p<0.0061 ) . Secondary preventive CRT implantation was associated with a higher likelihood of VA . As determined by ROC analysis an increase of LVEF by > 7 % was found to be a predictor of a significantly lower incidence of VA ( AUC = 0.606 ) . Conclusions Improvement of left ventricular function under cardiac resynchronization therapy goes along with a reduced incidence of ventricular arrhythmia Background — We hypothesized that patients with heart failure ( HF ) who recover left ventricular function ( HF-Recovered ) have a distinct clinical phenotype , biology , and prognosis compared with patients with HF with reduced ejection fraction ( HF-REF ) and those with HF with preserved ejection fraction ( HF-PEF ) . Methods and Results — The Penn Heart Failure Study ( PHFS ) is a prospect i ve cohort of 1821 chronic HF patients recruited from tertiary HF clinics . Participants were divided into 3 categories based on echocardiograms : HF-REF if EF was < 50 % , HF-PEF if EF was consistently ≥50 % , and HF-Recovered if EF on enrollment in PHFS was ≥50 % but prior EF was < 50 % . A significant portion of HF-Recovered patients had an abnormal biomarker profile at baseline , including 44 % with detectable troponin I , although in comparison , median levels of brain natriuretic factor , soluble fms-like tyrosine kinase receptor-1 , troponin I , and creatinine were greater in HF-REF and HF-PEF patients . In unadjusted Cox models over a maximum follow-up of 8.9 years , the hazard ratio for death , transplantation , or ventricular assist device placement in HF-REF patients was 4.1 ( 95 % confidence interval , 2.4–6.8 ; P<0.001 ) and in HF-PEF patients was 2.3 ( 95 % confidence interval , 1.2–4.5 ; P=0.013 ) compared with HF-Recovered patients . The unadjusted hazard ratio for cardiac hospitalization in HF-REF patients was 2.0 ( 95 % confidence interval , 1.5–2.7 ; P<0.001 ) and in HF-PEF patients was 1.3 ( 95 % confidence interval , 0.90–2.0 ; P=0.15 ) compared with HF-Recovered patients . Results were similar in adjusted models . Conclusions — HF-Recovered is associated with a better biomarker profile and event-free survival than HF-REF and HF-PEF . However , these patients still have abnormalities in biomarkers and experience a significant number of HF hospitalizations , suggesting persistent HF risk AIMS Some patients show such an important clinical improvement and reverse remodelling after cardiac resynchronization therapy ( CRT ) that anatomy and function approach normal . These patients have been called ' super-responders ' . The aim of our study was to identify predictors of becoming a super-responder after CRT . METHODS AND RESULTS Eighty-seven consecutive patients who underwent CRT were prospect ively studied . Before CRT and 6 months after , clinical and echocardiographic evaluation was performed . Patients with a decrease in New York Heart Association functional class > or=1 , a two-fold or more increase of left ventricular ejection fraction ( LVEF ) or a final LVEF > 45 % , and a decrease in LV end-systolic volume > 15 % were classified as super-responders . There were 12 % super-responders . At baseline , there were no significant differences between super-responders and the other patients , except for the fact that super-responders had significantly smaller mitral regurgitation and LV end-diastolic diameter ( LVEDD ) and a shorter duration of heart failure symptoms . Mitral regurgitation jet area , LVEDD , and duration of heart failure symptoms were correlated with this super-response . Moreover , an evolution of symptoms for < 12 months was an independent predictor of super-response to CRT . CONCLUSION Patients in earlier phases of the cardiomyopathy , with a less altered ventricular geometry , seem to have a greater probability of becoming super-responders AIMS The aim of this study was to determine the relationship between improved ejection fraction ( EF ) and occurrence of arrhythmias in patients with cardiac resynchronization therapy devices with defibrillator function ( CRT-D ) . The hypothesis was that patients who experienced a marked improvement in EF also had fewer appropriate defibrillator interventions . METHODS AND RESULTS We analysed data of 270 patients from 2 prospect i ve registries with follow-up of ≥12 months and echocardiography performed ≥8 months after CRT-D implantation . The discriminator was whether left ventricular ejection fraction ( LVEF ) improved to > 35 % [ cut-off for primary prevention implantable cardioverter-defibrillator ( ICD ) implantation ] . Mean age was 61±11 years , LVEF 22±5 % , and follow-up 40±22 months . Ischaemic cardiomyopathy was present in 48 % , and secondary prevention indication was present in 25 % . Implantable cardioverter-defibrillator interventions were delivered to 35 % of patients . Echocardiography ( 20±15 months after implantation ) showed an improvement in LVEF from 22 % ( SD 5.4 % ) to 30 % ( SD 9.8 % ) . Improvement to > 35 % was seen in 21 % of patients . Those who improved to > 35 % had fewer ICD interventions than those who did not ( 23 vs.38 % ; P-value 0.03 ) . Analysing only patients with a primary prevention indication and stratifying again in patients with and without improvement of LVEF to > 35 % , the latter had highly significant more ICD-therapies ( 6 vs. 31 % ; P-value 0.0008 ) . CONCLUSION Patients with CRT-D for primary prevention , whose LVEF improved to > 35 % during mid-term follow-up , are at low risk of first ICD therapies beyond year 1 . If similar findings are reported in other patient cohorts , this might impact on decision-making at the time of battery depletion BACKGROUND As left ventricular ejection fraction ( LVEF ) may improve , worsen , or remain the same over time , patients ' prognosis may also be expected to change because of the change in LVEF , among other factors . OBJECTIVE To evaluate the effect of LVEF change on outcome in the Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation ( DEFINITE ) trial . METHODS Patients with nonischemic cardiomyopathy with LVEF<36 % , history of symptomatic heart failure , and the presence of significant ventricular ectopic activity were enrolled in the DEFINITE trial . Follow-up LVEF measurements were obtained annually in only a minority ( 17 % ) of trial participants . This study therefore evaluated survival and arrhythmic end points in patients whose LVEF was reassessed between 90 and 730 days after enrollment . RESULTS During the 90 - 730-day postr and omization period , 187 of 449 ( 42 % ) enrolled patients who survived at least 90 days had at least 1 follow-up LVEF measurement ; these patients were younger and white ; had diabetes , better 6-minute walk test results , and higher BMI ; were more likely to have appropriate shocks ; and had fewer deaths compared to those without follow-up LVEF measurements . Patients whose LVEF improved had reduced mortality compared to patients whose LVEF decreased ( hazard ratio 0.09 ; 95 % confidence interval 0.02 - 0.39 ; P = .001 ) . Survival free of appropriate shocks was not significantly related to LVEF improvement during follow-up . CONCLUSIONS LVEF improvement was associated with improved survival , but not with a significant decrease in appropriate shocks . These data highlight that appropriate caution should be exercised not to extrapolate the positive effect of improved L 
    Output:
    
Conclusion In heart failure patients , we identified several baseline characteristics in favour of an improved LVEF , in response to evidence based therapy .
Patients with improved LVEF had significantly lower risks of mortality and appropriate shocks compared with patients with persistently reduced LVEF