***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: OBJECTIVES The purpose of this multicenter r and omized trial was to compare total mortality during therapy with amiodarone or an implantable cardioverter-defibrillator ( ICD ) in patients with nonischemic dilated cardiomyopathy ( NIDCM ) and nonsustained ventricular tachycardia ( NSVT ) . BACKGROUND Whether an ICD reduces mortality more than amiodarone in patients with NIDCM and NSVT is unknown . METHODS One hundred three patients with NIDCM , left ventricular ejection fraction < or = 0.35 , and asymptomatic NSVT were r and omized to receive either amiodarone or an ICD . The primary end point was total mortality . Secondary end points included arrhythmia-free survival , quality of life , and costs . RESULTS The study was stopped when the prospect i ve stopping rule for futility was reached . The percent of patients surviving at one year ( 90 % vs. 96 % ) and three years ( 88 % vs. 87 % ) in the amiodarone and ICD groups , respectively , were not statistically different ( p = 0.8 ) . Quality of life was also similar with each therapy ( p = NS ) . There was a trend with amiodarone , as compared to the ICD , towards improved arrhythmia-free survival ( p = 0.1 ) and lower costs during the first year of therapy ( $ 8,879 US dollars vs. $ 22,039 US dollars , p = 0.1 ) . CONCLUSIONS Mortality and quality of life in patients with NIDCM and NSVT treated with amiodarone or an ICD are not statistically different . There is a trend towards a more beneficial cost profile and improved arrhythmia-free survival with amiodarone therapy Background —Although implantable cardioverter-defibrillators ( ICDs ) reduce mortality in primary prevention patients with left ventricular systolic dysfunction , recent studies have question ed their overall role in clinical practice , especially in older patients and those with major comorbid conditions . Methods and Results —In a prospect i ve cohort of 965 patients with ischemic and nonischemic cardiomyopathies ( ejection fraction ≤35 % ) and no prior ventricular arrhythmias , we compared long-term mortality in patients who did ( n=494 [ 51 % ] ) and did not receive ICDs over a mean follow-up period of 34±16 months . Using a l and mark analysis , multivariable Cox proportional hazards models that included propensity scores for ICD implantation assessed the relationship between ICD therapy and mortality in the entire cohort and by age and the presence of major comorbid conditions . Data from these analyses were then used as inputs in a Markov model to generate incremental cost-effectiveness ratios for ICD therapy . Patients who received ICDs were similar in age and prevalence of most major comorbid conditions , including symptomatic heart failure . After multivariable adjustment , ICD therapy was associated with a 31 % lower risk for all-cause mortality ( adjusted hazard ratio , 0.69 ; 95 % CI , 0.50 to 0.96 ; P=0.03 ) . The relationship between ICD therapy and lower all-cause mortality was consistent after stratification by age ( < 65 , 65 to 74 , and ≥75 ) , ischemic etiology , ejection fraction ( > 25 % versus ≤25 % ) , and the presence of major comorbid conditions ( probability values for all interactions > 0.05 ) . Incremental cost-effectiveness ratios  for ICD therapy were similar between patients aged ≥75 years and younger patients but rose slightly in those with multiple comorbid conditions . Conclusions —Routine use of ICDs in primary prevention patients with left ventricular systolic dysfunction was associated with lower all-cause mortality , even among older patients and those with major comorbid conditions . Although their use needs to be individualized , our findings suggest that these groups should not be routinely excluded from ICD treatment BACKGROUND Implantable cardioverter-defibrillator ( ICD ) therapy has been shown to improve survival in patients with various heart conditions who are at high risk for ventricular arrhythmias . Whether benefit occurs in patients early after myocardial infa rct ion is unknown . METHODS We conducted the Defibrillator in Acute Myocardial Infa rct ion Trial , a r and omized , open-label comparison of  ICD therapy ( in 332 patients ) and no ICD therapy ( in 342 patients ) 6 to 40 days after a myocardial infa rct ion . We enrolled patients who had reduced left ventricular function ( left ventricular ejection fraction , 0.35 or less ) and impaired cardiac autonomic function ( manifested as depressed heart-rate variability or an elevated average 24-hour heart rate on Holter monitoring ) . The primary outcome was mortality from any cause . Death from arrhythmia was a predefined secondary outcome . RESULTS During a mean ( + /-SD ) follow-up period of 30+/-13 months , there was no difference in overall mortality between the two treatment groups : of the 120 patients who died , 62 were in the ICD group and 58 in the control group ( hazard ratio for death in the ICD group , 1.08 ; 95 percent confidence interval , 0.76 to 1.55 ; P=0.66 ) . There were 12 deaths due to arrhythmia in the ICD group , as compared with 29 in the control group ( hazard ratio in the ICD group , 0.42 ; 95 percent confidence interval , 0.22 to 0.83 ; P=0.009 ) . In contrast , there were 50 deaths from nonarrhythmic causes in the ICD group and 29 in the control group ( hazard ratio in the ICD group , 1.75 ; 95 percent confidence interval , 1.11 to 2.76 ; P=0.02 ) . CONCLUSIONS Prophylactic ICD therapy does not reduce overall mortality in high-risk patients who have recently had a myocardial infa rct ion . Although ICD therapy was associated with a reduction in the rate of death due to arrhythmia , that was offset by an increase in the rate of death from nonarrhythmic causes IMPORTANCE R and omized clinical trials have shown that implantable cardioverter-defibrillator ( ICD ) therapy saves lives . Whether the survival of patients who received an ICD in primary prevention clinical trials differs from that of trial-eligible patients receiving a primary prevention ICD in clinical practice is unknown . OBJECTIVE To determine whether trial-eligible patients who received a primary prevention ICD as documented in a large national registry have a survival rate that differs from the survival rate of similar patients who received an ICD  in the 2 largest primary prevention clinical trials , MADIT-II ( n = 742 ) and SCD-HeFT ( n = 829 ) . DESIGN , SETTING , AND PATIENTS Retrospective analysis of data for patients enrolled in the National Cardiovascular Data Registry ICD Registry between January 1 , 2006 , and December 31 , 2007 , meeting the MADIT-II criteria ( 2464 propensity score-matched patients ) or the SCD-HeFT criteria ( 3352 propensity score-matched patients ) . Mortality data for the registry patients were collected through December 31 , 2009 . MAIN OUTCOME MEASURES Cox proportional hazards models were used to compare mortality from any cause . RESULTS The median follow-up time in MADIT-II , SCD-HeFT , and the ICD Registry was 19.5 , 46.1 , and 35.2 months , respectively . Compared with patients enrolled in the clinical trials , patients in the ICD Registry were significantly older and had a higher burden of comorbidities . In the matched cohorts , there was no significant difference in survival between MADIT-II-like patients in the registry and MADIT-II patients r and omized to receive an ICD ( 2-year mortality rates : 13.9 % and 15.6 % , respectively ; adjusted ICD Registry vs trial hazard ratio , 1.06 ; 95 % CI , 0.85 - 1.31 ; P = .62 ) . Likewise , the survival among SCD-HeFT-like patients in the registry was not significantly different from survival among patients r and omized to receive ICD therapy in SCD-HeFT ( 3-year mortality rates : 17.3 % and 17.4 % , respectively ; adjusted registry vs trial hazard ratio , 1.16 ; 95 % CI , 0.97 - 1.38 ; P = .11 ) . CONCLUSIONS AND RELEVANCE There was no significant difference in survival between clinical trial patients r and omized to receive an ICD and a similar group of clinical registry patients who received a primary prevention ICD . Our findings support the continued use of primary prevention ICDs in similar patients seen in clinical practice . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00000609 Background —Prophylactic implantable defibrillators ( ICDs ) improve survival in patients with impaired ventricular function after myocardial infa rct ion ( MI ) , but it is uncertain whether mortality risk and survival benefit depend on the elapsed time from MI . Methods and Results —The Multicenter Automatic Defibrillator Implantation Trial II examined the impact of ICDs on survival in post-MI patients with ejection fractions ≤30 % . In 1159 patients , mean time from most recent MI to enrollment was 81±78 months . Patients were r and omized to an ICD ( n=699 ) or conventional care ( n=460 ) in a 3:2 ratio . Mortality rates ( deaths per 100 person-years of follow-up ) in both treatment groups were analyzed by time from MI divided into quartiles ( < 18 , 18 to 59 , 60 to 119 , and ≥120 months ) . In conventional care patients , these rates increased as time from MI increased ( 7.8 % , 8.4 % , 11.6 % , 14.0 % ; P = 0.03 ) . Mortality rates in ICD patients were consistently lower in each quartile and showed minimal increase over time ( 7.2 % , 4.9 % , 8.2 % , 9.0 % ; P = 0.19 ) . Covariate-adjusted hazard ratios for risk of death associated with ICD therapy were 0.97 ( 95 % CI , 0.51 to 1.81 ; P = 0.92 ) for recent MI ( < 18 months ) and 0.55 ( 95 % CI , 0.39 to 0.78 ; P = 0.001 ) for remote MI ( ≥18 months ) . Conclusions —Mortality risk in patients with ejection fractions ≤30 % increases as a function of time from MI . The survival benefit associated with ICDs appears to be greater for remote MI and remains substantial for up to ≥15 years after MI Background — Patients with idiopathic dilated cardiomyopathy ( DCM ) and impaired left ventricular ejection fraction have an increased risk of dying suddenly . Methods and Results — Patients with recent onset of DCM ( ≤9 months ) and an ejection fraction ≤30 % were r and omly assigned to the implantation of an implantable cardioverter-defibrillator ( ICD ) or control . The primary end point of the trial was all-cause mortality at 1 year of follow-up . The trial was terminated after the inclusion of 104 patients because the all-cause mortality rate at 1 year did not reach the expected 30 % in the control group . In August 2000 , the vital status of all patients was up date d by contacting patients , relatives , or local registration offices . One hundred four patients were enrolled in the trial : Fifty were assigned to ICD therapy and 54 to the control group . Mean follow-up was 22.8±4.3 months , on the basis of investigators ’ follow-up . After 1 year , 6 patients were dead ( 4 in the ICD group and 2 in the control group ) . No sudden death occurred during the first and second years of follow-up . In August 2000 , after a mean follow-up of 5.5±2.2 years , 30 deaths had occurred ( 13 in the ICD group and 17 in the control group ) . Cumulative survival was not significantly different between the two groups ( 93 % and 80 % in the control group versus 92 % and 86 % in the ICD group after 2 and 4 years , respectively ) . Conclusions —This trial did not provide evidence in favor of prophylactic ICD implantation in patients with DCM of recent onset and impaired left ventricular ejection fraction BACKGROUND The mortality rate among patients with coronary artery disease , abnormal ventricular function , and unsustained ventricular tachycardia is high . The usefulness of electrophysiologic testing for risk stratification in these patients is unclear . METHODS We performed electrophysiologic testing in patients who had coronary artery disease , a left ventricular ejection fraction of 40 percent or less , and asymptomatic , unsustained ventricular tachycardia . Patients in whom sustained ventricular tachyarrhythmias could be induced were r and omly assigned to receive either antiarrhythmic therapy guided by electrophysiologic testing or no antiarrhythmic therapy . The primary end point was cardiac arrest or death from arrhythmia .  Patients without inducible tachyarrhythmias were followed in a registry . We compared 
    Output:
    
Men vs. women : RORs of implantable cardioverter defibrillators vs. no implantable cardioverter defibrillators for all-cause mortality .
Younger vs. older subgroups :  RORs of implantable cardioverter defibrillators vs. no implantable cardioverter defibrillators