***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 The calcium sensitizer levosimendan has been used in cardiac surgery for the treatment of postoperative low cardiac output syndrome ( LCOS ) and difficult weaning from cardiopulmonary bypass ( CPB ) . OBJECTIVES To evaluate the effects of preoperative treatment with levosimendan on 30-day mortality , the risk of developing LCOS and the requirement for inotropes , vasopressors and intra-aortic balloon pumps in patients with severe left ventricular dysfunction . METHODS Patient with severe left ventricular dysfunction and an ejection fraction < 25 % undergoing coronary artery bypass grafting with CPB were admitted 24 h before surgery and were r and omly assigned to receive levosimendan ( loading dose 10 μg/kg followed by a 23 h continuous infusion of 0.1μg/kg/min ) or a placebo . RESULTS From December 1 , 2002 to June 1 , 2008 , a total of 252 patients were enrolled ( 127 in the levosimendan group and 125 in the control group ) . Individuals treated with levosimendan exhibited a lower incidence of complicated weaning from CPB ( 2.4 % versus 9.6 % ; P<0.05 ) , decreased mortality ( 3.9 % versus 12.8 % ; P<0.05 ) and a lower incidence of LCOS ( 7.1 % versus 20.8 % ; P<0.05 ) compared with the control group . The levosimendan group also had a lower requirement for inotropes ( 7.9 % versus 58.4 % ; P<0.05 ) , vasopressors ( 14.2 % versus 45.6 % ; P<0.05 ) and intra-aortic balloon pumps ( 6.3 % versus 30.4 % ; P<0.05 ) . CONCLUSION Patients with severe left ventricle dysfunction ( ejection fraction < 25 % ) undergoing coronary artery bypass grafting with CPB who were pretreated with levosimendan  exhibited lower mortality , a decreased risk for developing LCOS and a reduced requirement for inotropes , vasopressors and intra-aortic balloon pumps . Studies with a larger number of patients are required to confirm whether these findings represent a new strategy to reduce the operative risk in this high-risk patient population Background —The short-term infusion of levosimendan ( Levo ) improves hemodynamic function in patients with decompensated heart failure . The metabolites of Levo have a prolonged half-life , and one is hemodynamically active . The goal of this study was to determine whether the hemodynamic effects of Levo are sustained during a long-term infusion and beyond the discontinuation of drug infusion . Methods and Results — Patients with decompensated heart failure received escalating infusion rates of intravenous Levo  ( n=98 ) or placebo  ( n=48 ) for 6 hours . At the end of 6 hours , 85 of the Levo-treated patients were continued on open-label drug for a total of 24 hours , at which time they were r and omized 1:1 to an additional 24 hours of Levo ( n=43 ) or placebo (n=42).The hemodynamic effects observed at 24 hours were maintained at 48 hours in both the continuation and withdrawal groups and did not differ between groups . Although the plasma concentration of Levo decreased rapidly in the withdrawal group , concentrations of the active metabolite OR-1896 were similar in the continuation and withdrawal groups at 24 hours and increased further ( 3.5-fold to 4-fold ) and to a similar extent in both groups at 48 hours . Conclusions —The hemodynamic effects of Levo were maintained during a 48-hour continuous infusion and for at least 24 hours after discontinuation of a 24-hour infusion . The active metabolite OR-1896 increased for at least 24 hours after cessation of drug infusion and may account for the prolonged hemodynamic effects of Levo Importance Low cardiac output syndrome after cardiac surgery is associated with high morbidity and mortality in patients with impaired left ventricular function . Objective To assess the ability of preoperative levosimendan to prevent postoperative low cardiac output syndrome . Design , Setting , and Participants R and omized , double-blind , placebo-controlled trial conducted in 13 French cardiac surgical centers . Patients with a left ventricular ejection fraction less than or equal to 40 % and scheduled for isolated or combined coronary artery bypass grafting with cardiopulmonary bypass were enrolled from June 2013 until May 2015 and followed during 6 months ( last follow-up , November 30 , 2015 ) . Interventions Patients were assigned to a 24-hour infusion of levosimendan 0.1 µg/kg/min ( n = 167 ) or placebo ( n = 168 ) initiated after anesthetic induction . Main Outcomes and Measures Composite end point reflecting low cardiac output syndrome with need for a catecholamine infusion 48 hours after study drug initiation , need for a left ventricular mechanical assist device or failure to wean from it at 96 hours after study drug initiation when the device was inserted preoperatively , or need for renal replacement therapy at any time postoperatively . It was hypothesized that levosimendan would reduce the incidence of this composite end point by 15 % in comparison with placebo . Results Among 336 r and omized patients ( mean age , 68 years ; 16 % women ) , 333 completed the trial . The primary end point occurred in 87 patients ( 52 % ) in the levosimendan group and 101 patients ( 61 % ) in the placebo group ( absolute risk difference taking into account center effect , −7 % [ 95 % CI , −17 % to 3 % ] ; P = .15 ) . Predefined subgroup analyses found no interaction with ejection fraction less than 30 % , type of surgery , and preoperative use of & bgr;-blockers , intra-aortic balloon pump , or catecholamines . The prevalence of hypotension ( 57 % vs 48 % ) , atrial fibrillation ( 50 % vs 40 % ) , and other adverse events did not significantly differ between levosimendan and placebo . Conclusions and Relevance Among patients with low ejection fraction who were undergoing coronary artery bypass grafting with cardiopulmonary bypass , levosimendan compared with placebo did not result in a significant difference in the composite end point of prolonged catecholamine infusion , use of left ventricular mechanical assist device , or renal replacement therapy . These findings do not support the use of levosimendan for this indication . Trial Registration EudraCT Number : 2012 - 000232 - 25 ; clinical trials.gov Identifier : OBJECTIVES An analysis is made of the clinical profile , evolution and differences in morbidity and mortality of low cardiac output syndrome ( LCOS ) in the postoperative period of cardiac surgery , according to the 3 diagnostic subgroups defined by the SEMICYUC Consensus 2012 . DESIGN A multicenter , prospect i ve cohort study was carried out . SETTING ICUs of Spanish hospitals with cardiac surgery . PATIENTS A consecutive sample of 2,070 cardiac surgery patients was included , with the analysis of 137 patients with LCOS .  INTERVENTIONS No intervention was carried out . RESULTS The mean patient age was 68.3±9.3 years ( 65.2 % males ) , with a EuroSCORE II of 9.99±13 . NYHA functional class III-IV ( 52.9 % ) , left ventricular ejection fraction<35 % ( 33.6 % ) , AMI ( 31.9 % ) , severe PHT ( 21.7 % ) , critical preoperative condition ( 18.8 % ) , prior cardiac surgery ( 18.1 % ) ,  PTCA/stent placement ( 16.7 % ) . According to subgroups , 46 patients fulfilled hemodynamic criteria of LCOS ( group A ) , 50 clinical criteria ( group B ) , and the rest ( n=41 ) presented cardiogenic shock ( group C ) . Significant differences were observed over the evolutive course between the subgroups in terms of time subjected to mechanical ventilation ( 114.4 , 135.4 and 180.3min in groups A , B and C , respectively ; P<.001 ) , renal replacement requirements ( 11.4 , 14.6 and 36.6 % ; P=.007 ) , multiorgan failure ( 16.7 , 13 and 47.5 % ) , and mortality ( 13.6 , 12.5 and 35.9 % ; P=.01 ) . The mean maximum lactate concentration was higher in cardiogenic shock patients ( P=.002 ) . CONCLUSIONS The clinical evolution of these patients leads to high morbidity and mortality . We found differences between the subgroups in terms of the postoperative clinical course and mortality This study compared the effects of simendan , a calcium sensitizer , with those of milrinone and enalapril on survival of rats with healed myocardial infa rct ion . Seven days after ligation-induced myocardial infa rct ion , the rats were r and omized to control , milrinone , enalapril , or simendan groups . All compounds were administered via the drinking water for 312 days , at which time there was 80 % mortality in the control group -- the study 's primary endpoint . The infa rct sizes were similar across all groups . At endpoint , the mortality rates were : 63 % ( milrinone ) , 56 % ( enalapril ) and 53 % ( simendan ) ; the risk reductions were 25 % ( P = 0.04 vs. control ) and 28 % ( P = 0.02 vs. control ) with enalapril and simendan , respectively . Milrinone had no statistically significant effect on the survival rate . These findings suggest that , like enalapril , simendan improved survival in rats with healed myocardial infa rct ion Background : Off-pump coronary artery bypass surgery ( OPCAB ) is often complicated by hemodynamic instability , especially in patients with prior left ventricular ( LV ) dysfunction and appropriate choice of inotrope plays a vital role in perioperative management of these patients . Aim and Objective : To study hemodynamic effects and immediate outcome of prophylactic infusion of levosimendan in patients with the LV dysfunction undergoing OPCAB surgery and whether this strategy helps in successful conduct of OPCAB surgery . Material s and Methods : After Institutional Ethics Committee approval , 60 patients posted for elective OPCAB surgery were r and omly divided into two groups ( n = 30 each ) . Patients with the LV ejection fraction < 30 % were included . Study group was started on injection levosimendan ( @ 0.1 μg/kg/min ) in the previous night before surgery and continued for 24 h including intraoperative period . Hemodynamic monitoring included heart rate , invasive blood pressure , cardiac index ( CI ) , pulmonary capillary wedge pressure ( PCWP ) , pulse oximetry , and arterial blood gases with serum lactates at as T0 ( baseline ) , T1 ( 15 min after obtuse marginal and /or PDA anastomoses ) , T2 ( at end of surgery ) , T3 ( 6 h after surgery in Intensive Care Unit [ ICU ] ) , T4 ( 12 h after surgery ) , and T5 ( 24 h after surgery in ICU ) . Vasopressor was added to maintain mean arterial pressure > 60 mmHg . Chi-square/Fisher 's exact/Mid P exact test and Student 's t-tests were applied for categorical and continuous data . Results : CI was greater and PCWP reduced significantly in Group L during intraoperative and early postoperative period . Serum lactate concentration was lower in patients pretreated with levosimendan . Incidence of postoperative atrial fibrillation ( POAF ) ( 36.6 vs. 6.6 % ; P = 0.01 ) , low cardiac output syndrome ( LCOS ) ( 30 % vs. 6 % ; P = 0.02 ) , and acute kidney injury ( 23.3 % vs. 6.7 % ; P = 0.04 ) was less in Group L. Three patients ( 10 % ) in control group required conversion to cardiopulmonary bypass ( CPB ) as compared to none in the study group . There was no difference regarding ICU or hospital stay and mortality in both groups . Conclusion : Preoperative levosimendan helps in successful conduct of OPCAB and reduces the incidence of LCOS , POAF , conversion to CPB , and requirement of intra-aortic balloon pump CONTEXT Atrial fibrillation is a common , but potentially preventable , complication following coronary artery bypass graft ( CABG ) surgery . OBJECTIVES To assess the nature and consequences of atrial fibrillation after CABG surgery and to develop a comprehensive risk index that can better identify patients at risk for atrial fibrillation . DESIGN , SETTING , AND PARTICIPANTS Prospect i ve observational study of 4657 patients undergoing CABG surgery between November 1996 and June 2000 at 70 centers located within 17 countries , selected using a systematic sampling technique . From a derivation cohort of 3093 patients , associations between predictor variables and postoperative atrial fibrillation were identified to 
    Output:
    
Subgroup analyses revealed that such a benefit was mainly observed in the isolated CABG , the preoperative administration , with-bolus and on-pump subgroups .