***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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    ***EXAMPLES*** 
    Input: Background — The relationship between diabetes mellitus and risk of inappropriate or appropriate therapy in patients receiving an implantable cardioverter-defibrillator ( ICD ) and resynchronization therapy  has not been investigated thoroughly . The effect of innovative ICD programming on therapy delivery in these patients is unknown . Methods and Results — The Multicenter Automatic Defibrillator Implantation Trial – Reduce Inappropriate Therapy ( MADIT-RIT ) r and omized patients with a primary prophylactic ICD indication to 3 different types of ICD programming : conventional programming with a ventricular tachycardia zone of 170 to 199 bpm ( arm A ) , high-rate cutoff with a ventricular tachycardia zone ≥200 bpm ( arm B ) , or 60-second-delayed therapy ( arm C ) . The end points of inappropriate therapy , appropriate therapy , and death were assessed among 485 patients with and 998 without diabetes mellitus . Innovative ICD programming reduced the risk of inappropriate therapy regardless of diabetes mellitus , although a trend toward a more pronounced effect of high-rate cutoff programming was seen in patients without diabetes mellitus ( P for interaction=0.06 ) . Diabetes mellitus was associated with a decreased risk of inappropriate therapy ( hazard ratio , 0.54 ; 95 % confidence interval , 0.36–0.80 ; P=0.002 ) and increased risk of appropriate therapy ( hazard ratio , 1.58 ; 95 % confidence interval , 1.17–2.14 ; P=0.003 ) . In diabetic patients , there was significantly increased risk of death in those who had inappropriate therapy ( hazard ratio , 4.17 ; 95 % confidence interval , 1.52–11.40 ; P=0.005 ) and appropriate therapy ( hazard ratio , 2.49 ; 95 % confidence interval , 1.06–5.87 ; P=0.037 ) compared with those who did not . Conclusions — Innovative high-rate cutoff or delayed ICD programming was associated with a reduction in inappropriate therapy in patients with and without diabetes mellitus . Diabetes mellitus was associated with lower risk of inappropriate therapy but higher risk of appropriate therapy . Appropriate and inappropriate ICD therapy was associated with increased mortality in diabetic patients . Clinical Trial Registration — URL : http://www . clinical trials.gov . Unique identifier : NCT00947310 BACKGROUND Current guidelines do not recommend implantable cardioverter-defibrillator ( ICD ) implantation  in patients with a life expectancy of < 1 year . Better methods are needed for identifying patients at high risk for early mortality despite ICD therapy . OBJECTIVE To develop and vali date a risk prediction score to identify patients at high risk for death within 1 year despite ICD therapy . DESIGN Detailed clinical data were collected on a large observational cohort of ICD patients from 3 tertiary care centers . One-third of the patients were r and omly selected to form the prediction group ( PG ) from which a risk score was developed using logistic regression . This score was then applied to the remaining two-thirds of the cohort ( validation group [ VG ] ) to assess the risk score 's predictive accuracy . RESULTS The total cohort included 2717 ICD patients ( mean age = 64.6 ± 14.5 , male = 77.2 % , primary prevention = 74.7 % ) . A simple risk score incorporating peripheral arterial disease , age ≥ 70 years , creatinine ≥ 2.0 mg/dL , and ejection fraction ≤20 % ( PACE ) accurately predicted 1-year mortality in the VG . Patients with a risk score of ≥3 had a > 4-fold excess 1-year mortality compared with patients with a risk score of <3 ( 16.5 % vs 3.5 % ; P < .0001 ) . LIMITATION Risk reduction provided by ICD therapy in this cohort is not known given the lack of a control group . CONCLUSIONS A simple risk score accurately predicts 1-year mortality in ICD patients , as patients with a PACE risk score of ≥3 are at high risk despite ICD therapy Background — Implantable cardioverter-defibrillators ( ICDs ) improve survival in selected patients with left ventricular systolic dysfunction in r and omized trials . Competing death without prior appropriate ICD therapy might preclude benefit from ICD implantation in a less selected routine-care population . Methods and Results — We selected all patients with ischemic or dilated cardiomyopathy with an ICD implanted for primary or secondary prevention from a single-center prospect i ve registry between 1994 and 2006 . The end point was time to first appropriate ICD therapy/confirmed ventricular fibrillation or death without prior appropriate ICD therapy . We analyzed cumulative incidence functions and used competing risk regression to study predictors of appropriate ICD therapy or prior death . In 442 patients , 73 deaths  occurred during a median follow-up of 3.6 years ( maximum , 12.7 years ) . The cumulative incidence of first appropriate ICD therapy until year 7 was 52 % , whereas 11 % died without prior ICD therapy . The cumulative incidence of appropriate ICD therapy for ventricular fibrillation was 13 % , whereas 23 % died without prior therapy for ventricular fibrillation . Appropriate ICD therapy was twice as likely in secondary prevention compared with primary prevention , whereas death rates before ICD therapy were similar in both groups . Diuretic use for heart failure compared with nonuse predicted a 4-fold-increased risk of death prior to ICD therapy , although the incidence of appropriate ICD therapy was similar in both groups . Conclusion — In a contemporary ICD population , the risk of death without prior appropriate ICD therapy is substantial , especially in patients with advanced heart failure BACKGROUND AND AIM Effectiveness of implantable cardioverter-defibrillators ( ICD ) in patients with reduced left ventricular ejection fraction after myocardial infa rct ion has been documented in large r and omised trials . We analysed the predictive value of clinical factors at the time of implantation for adequate ICD interventions and mortality risk . METHODS We analysed 121 consecutive patients ( 15 women , 106 [ 88 % ] men ; mean age 62 ± 10 years ) with coronary artery disease in whom ICD was implanted for primary prevention between 2001 and 2007 . Mean duration of follow-up was 876 ± 538 days . RESULTS Forty-four ( 36.4 % ) patients had adequate ICD interventions . In the Cox analysis , wider QRS complexes ( hazard ration [ HR ] per each 10 ms increment : 1.13 , confidence interval [ CI ] 1.039 - 1.229 , p = 0.0045 ) and younger age at the time of ICD implantation ( HR per each 10 year increment : 0.7 , CI 0.5 - 0.9 , p = 0.0081 ) were associated with a higher probability of adequate intervention . Wider QRS complexes were associated with a higher probability of electrical storm ( HR 1.059 , CI 1.014 - 1.045 , p = 0.0002 ) . During follow-up , 21 ( 17.4 % ) patients died . In the Cox analysis , wider QRS complexes ( HR per each 10 ms increment : 1.123 , CI 1.011 - 1.248 , p = 0.0306 [ in univariate analysis only ] ) , older age at the time of implantation ( HR per each 10 year increment : 1.7 , CI 1.1 - 2.8 , p = 0.0396 ) and higher NYHA class ( HR 4.4 , CI 1.7 - 11.5 , p = 0.0022 ) were associated with increased mortality . Mortality was reduced by previous revascularisation ( HR 0.3 , CI 0.1 - 0.7 , p = 0.006 ) . CONCLUSIONS Patients with wider QRS complexes at the time of ICD implantation had a higher probability of adequate device intervention and mortality risk . QRS complex widening was also associated with a higher incidence of electrical storm BACKGROUND Sudden death from cardiac causes remains a leading cause of death among patients with congestive heart failure ( CHF ) . Treatment with amiodarone or an implantable cardioverter-defibrillator ( ICD ) has been proposed to improve the prognosis in such patients . METHODS We r and omly assigned 2521 patients with New York Heart Association ( NYHA ) class II or III CHF and a left ventricular ejection fraction ( LVEF ) of 35 percent or less to conventional therapy for CHF plus placebo ( 847 patients ) , conventional therapy plus amiodarone ( 845 patients ) , or conventional therapy plus a conservatively programmed , shock-only , single-lead ICD ( 829 patients ) . Placebo and amiodarone were administered in a double-blind fashion . The primary end point was death from any cause . RESULTS The median LVEF in patients was 25 percent ; 70 percent were in NYHA class II , and 30 percent were in class III CHF . The cause of CHF was ischemic in 52 percent and nonischemic in 48 percent . The median follow-up was 45.5 months . There were 244 deaths ( 29 percent ) in the placebo group , 240 ( 28 percent ) in the amiodarone group , and 182 ( 22 percent ) in the ICD group . As compared with placebo , amiodarone was associated with a similar risk of death ( hazard ratio , 1.06 ; 97.5 percent confidence interval , 0.86 to 1.30 ; P=0.53 ) and ICD therapy was associated with a decreased risk of death of 23 percent ( 0.77 ; 97.5 percent confidence interval , 0.62 to 0.96 ; P=0.007 ) and an absolute decrease in mortality of 7.2 percentage points after five years in the overall population . Results did not vary according to either ischemic or nonischemic causes of CHF , but they did vary according to the NYHA class . CONCLUSIONS In patients with NYHA class II or III CHF and LVEF of 35 percent or less , amiodarone has no favorable effect on survival , whereas single-lead , shock-only ICD therapy reduces overall mortality by 23 percent BACKGROUND Patients with reduced left ventricular function after myocardial infa rct ion are at risk for life-threatening ventricular arrhythmias . This r and omized trial was design ed to evaluate the effect of an implantable defibrillator on survival in such patients . METHODS Over the course of four years , we enrolled 1232 patients with a prior myocardial infa rct ion and a left ventricular ejection fraction of 0.30 or less . Patients were r and omly assigned in a 3:2 ratio to receive an implantable defibrillator ( 742 patients ) or conventional medical therapy ( 490 patients ) . Invasive electrophysiological testing for risk stratification was not required . Death from any cause was the end point . RESULTS The clinical characteristics at base line and the prevalence of medication use at the time of the last follow-up visit were similar in the two treatment groups . During an average follow-up of 20 months , the mortality rates were 19.8 percent in the conventional-therapy group and 14.2 percent in the defibrillator group . The hazard ratio for the risk of death from any cause in the defibrillator group as compared with the conventional-therapy group was 0.69 ( 95 percent confidence interval , 0.51 to 0.93 ; P=0.016 ) . The effect of defibrillator therapy on survival was similar in subgroup analyses stratified according to age , sex , ejection fraction , New York Heart Association class , and the QRS interval . CONCLUSIONS In patients with a prior myocardial infa rct ion and advanced left ventricular dysfunction , prophylactic implantation of a defibrillator improves survival and should be considered as a recommended therapy Background Less than 50 % of patients implanted with an implantable cardioverter-defibrillator ( ICD )  receive device therapy during the follow-up . The aim of our study was to prospect ively evaluate the predictive role of appropriate ICD therapy on long-term survival of patients implanted for primary or secondary sudden death prevention . Methods From 2002 to 2003 , 139 consecutive patients [ mean age 66 ± 9 years , male 77 % , ischemic heart disease 56 % , New York Heart Association functional class > II ( 74 % ) , primary prevention 74 % , mean left ventricular ejection fraction 30 ± 9 % , cardiac resynchronization ICD 65 % ] were enrolled . We collected and evaluated device therapies for at least 18 months and recorded survival status for more than 5 years . Results Over a median follow-up of 18 months , 54 ( 39 % ) patients received at least one ICD intervention , with 28 patients receiving only appropriate ICD therapies , 13 only inappropriate therapies and 13 receiving both therapies . At a mean follow-up of 63 ± 12 months , 30 deaths occurred in 130 patients ( 23 % 
    Output:
    
In this meta- analysis of contemporary clinical studies , all-cause mortality is predicted by a variety of clinical characteristics including LVEF .
On the other h and , the risk of appropriate shocks might be associated with impaired LVEF and ischemic cardiomyopathy .