***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: INTRODUCTION Atrial fibrillation ( AF ) is the most common complication after coronary artery bypass grafting ( CABG ) . Conventional clinical practice is to treat AF after its onset in the postoperative period . However effective prophylaxis can result in reduced morbidity and hospital stay . This prospect i ve study was design ed to assess the efficacy of right atrial pacing in the prevention of postoperative AF following CABG . METHODS All patients who had isolated first time CABG on cardiopulmonary bypass between January 2007 and June 2007 , operated by one surgeon were included in this study ( study group ) . During the same period , isolated CABG carried out by other surgeons in the same unit and not paced served as control ( control group ) . In the study group ( n=24 ) right atrial pacing was continued for 96h in the postoperative period . The end points of the study were occurrence of AF , death in postoperative period or discharge from hospital . RESULTS In the study group 5 patients could not be paced because of persistent tachycardia or failure of atrial electrodes . There was a statistically significant reduction in the incidence of postoperative atrial fibrillation from 31.1 % in control group to 5.2 % ( p-value 0.03 ) in patients who were paced . CONCLUSIONS The preliminary results of this study suggest that prophylactic right atrial pacing significantly reduced the incidence of AF following CABG . However these results need to be confirmed in a larger cohort of patients in a prospect i ve r and omised trial Background  Atrial fibrillation ( AF )  increases the morbidity of CABG . The pathophysiology is uncertain , and its prevention remains suboptimal . This prospect i ve , r and omized study was design ed to define the role of cardiopulmonary bypass ( CPB ) and cardioplegic arrest in the pathogenesis of this complication . Methods and Results Two hundred patients were prospect ively r and omized to ( 1 ) on-pump conventional surgery [ ( 100 patients , 79 men , mean age 63 ( 40 to 77 ) years ) ] with normothermic CPB and cardioplegic arrest of the heart or ( 2 ) off-pump surgery [ ( 100 patients , 82 men , mean age 63 ( 38 to 86 ) years ) ] on the beating heart .  Heart rate and rhythm were continuously monitored with an automated arrhythmia detector during the first 72 hours after surgery . Thereafter , routine clinical observation was performed and continuous monitoring restarted in the case of arrhythmia . The association of perioperative factors with AF was investigated by univariate analysis . Significant variables were then included into a stepwise logistic regression model to ascertain their independent influence on the occurrence of AF . There were no significant baseline differences between groups . Thirty-nine patients in the on-pump group and 8 patients in the off-pump group had postoperative sustained AF ( P = 0.001 ) . Univariate analysis showed that CPB inclusive of cardioplegic arrest , postoperative inotropic support , intubation time , chest infection , and hospital length of stay were predictors of AF ( all P < 0.05 ) . However , stepwise multivariate regression analysis identified CPB inclusive of cardioplegic arrest as the only independent predictor of postoperative AF ( OR 7.4 ; CI 3.4 to 17.9 ) . Conclusions CPB inclusive of cardioplegic arrest is the main independent predictor of postoperative AF in patients undergoing coronary revascularization Background — Atrial fibrillation ( AF ) after coronary artery bypass graft surgery is a difficult problem and a continuing source of morbidity and mortality . However , the prognostic implication s of postoperative AF are still in dispute . Our aim was to ascertain the impact of AF after coronary artery bypass graft on postoperative survival and to assess its prognostic role in cause-specific mortality . Methods and Results — We conducted a prospect i ve observational study of 1832 patients undergoing isolated coronary artery bypass graft between January 2000 and December 2005 at 2 cardiac surgery centers in northern Italy . Patients affected by postoperative AF were identified and followed up until death or study end ( April 30 , 2007 ) . A total of 570 patients ( 31 % ) developed AF after coronary surgery  . Patients affected by postoperative AF experienced a longer hospital stay ( 7 days [ 25th to 75th percentile , 7 to 10 days ] versus 7 days [ 25th to 75th percentile , 6 to 8 days ] ; P<0.001 ) . Hospital mortality also was higher in AF patients ( 3.3 % versus 0.5 % ; P<0.001 ) . On discharge , 1806 patients were alive ; 143 were lost to follow-up . The remaining 1663 were followed up for a median of 51 months ( 25th to 75th percentile , 41 to 63 months ) ; 126 of them died after a median of 14 months ( 25th to 75th percentile , 5 to 32 months ) . Long-term mortality rates were significantly higher for patients with postoperative AF ( 2.99 per 100 person-years ; 95 % confidence interval , 2.33 to 3.84 ; 61 deaths ) compared with those without the arrhythmia ( 1.34 per 100 person-years ; 95 % confidence interval , 1.05 to 1.71 ; 65 deaths ) , with an adjusted hazard ratio of 2.13 ( P<0.001 ) and 2.56 ( P=0.001 ) when also accounting for the prescription of warfarin at discharge . With Cox regression , patients with AF were shown to be at higher risk of dying from embolism ( adjusted hazard ratio , 4.33 ; 95 % confidence interval , 1.78 to 10.52 ) but not from other causes . Conclusions — Postoperative AF affects early and late mortality after isolated coronary artery bypass graft surgery . Patients affected by AF are at higher risk of fatal embolic events . Careful postoperative surveillance with a specific antiarrhythmic and antithrombotic prophylaxis , aim ed at reducing AF and its complications , is recommended OBJECTIVE The study objective was to determine the predictors of postoperative atrial fibrillation ( POAF ) in patients r and omized to conventional coronary artery bypass graft ( on-pump coronary artery bypass [ ONCAB ] ) versus beating heart coronary surgery ( off-pump coronary artery bypass [ OPCAB ] ) .  METHODS The subgroup of 2103 patients ( of 2203 enrollees ) in the R and omized On Versus Off Bypass trial with no POAF was studied ( 1056 patients in the ONCAB group and 1047 patients in the OPCAB group ) . Univariate and multivariate analyses were used to identify the predictors of POAF and the impact of POAF on outcomes . RESULTS Use of ONCAB versus OPCAB was not associated with increased rates of POAF . Older age ( P < .0001 ) , white race ( P < .001 ) , and hypertension ( P < .002 ) were predictors of POAF on multivariate analysis . In general , POAF led to a higher rates of reintubation ( ONCAB : 6.3 % vs 0.8 % no POAF , P < .001 ; OPCAB : 7.4 % vs 1.8 % no POAF , P < .0001 ) and prolonged ventilatory support ( ONCAB : 7.1 % vs 2.3 % no POAF , P = .001 ; OPCAB : 9.2 % vs 3.4 % no POAF , P = .0003 ) . The rate of any early adverse outcome was higher in patients with POAF ( all patients : 10 % POAF vs 4.7 % no POAF , P < .0001 ; ONCAB : 9 % POAF vs 4.3 % no POAF , P = .008 ; OPCAB : 11 % POAF vs 5.1 % no POAF , P = .001 ) . The 1-year all cause mortality was higher with POAF for both groups ( ONCAB : 5.4 % POAF vs 2 % no POAF , P = .009 ; OPCAB : 5.1 % POAF vs 2.6 % no POAF , P = .07 ) . POAF was independently associated with early composite end point ( odds ratio [ OR ] , 2.23 ; confidence interval [ CI ] , 1.55 - 3.22 ; P < .0001 ) , need for new mechanical support ( OR , 3.25 ; CI , 1.39 - 7.61 ; P = .007 ) , prolonged ventilatory support ( OR , 2.93 ; CI , 1.89 - 4.55 ; P < .0001 ) , renal failure ( OR , 5.42 ; CI , 1.94 - 15.15 ; P = .001 ) , and mortality at 12 months ( OR , 1.94 ; CI , 1.14 - 3.28 ; P = .01 ) . CONCLUSIONS In the R and omized On Versus Off Bypass trial , the strategy of revascularization did not affect the rate of POAF . Age , race , and hypertension were predictors of POAF . POAF was independently associated with a higher short-term morbidity and higher 1-year mortality rates OBJECTIVE Atrial fibrillation is the most frequently encountered postoperative arrhythmic complication after coronary artery bypass grafting .  Ischemic preconditioning has proved a potent endogenous factor in suppressing ischemia-reperfusion-induced arrhythmias . The protective effect of ischemic preconditioning on atrial fibrillation after coronary artery bypass grafting has not been studied . The purpose of the present study was to investigate whether ischemic preconditioning had an effect on postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting . METHODS Eighty-five patients undergoing coronary artery bypass grafting  were r and omized into ischemic preconditioning and control groups . Holter data from 24-hour electrocardiography were collected 1 day before the operation to the second postoperative day . Atrial fibrillation was registered as positive if any atrial fibrillation event occurred . RESULTS The overall incidence of postoperative atrial fibrillation and sustained atrial fibrillation was 34.1 % and 27.1 % , respectively . The occurrence of atrial fibrillation was significantly lower in the ischemic preconditioning group ( 21.4 % in patients undergoing ischemic preconditioning and 46.5 % in control subjects , P = .015 ) . Preoperative recent unstable angina did not influence the incidence of atrial fibrillation . Patients with atrial fibrillation had longer intensive care unit stays and compromised postoperative hemodynamic outcomes . Binary logistic regression analysis showed that  ischemic preconditioning , preoperative mean heart rate , and postoperative pulmonary capillary wedge pressure were the independent predictors of atrial fibrillation . CONCLUSIONS Postcoronary artery bypass grafting atrial fibrillation is associated with more complicated postoperative outcome . Higher preoperative heart rate and postoperative pulmonary capillary wedge pressure were the independent predictors of atrial fibrillation . Recent unstable angina is not related to the occurrence of postcoronary artery bypass grafting atrial fibrillation . Ischemic preconditioning significantly suppresses postcoronary artery bypass grafting atrial fibrillation , suggesting that ischemic preconditioning can be used as an effective prophylactic method for postoperative atrial fibrillation OBJECTIVES Despite all the advances in cardiac surgery , atrial fibrillation ( AF ) remains a common postoperative complication with unclear predisposing factors . Postoperative AF is often a short-lived and a self-limiting condition , but can result in debilitating and even lethal consequences . The aim of this study is to assess the effect of AF on patients postcardiac surgery . METHODS In this retrospective study , we prospect ively review ed patient data for our institution for a 10-year period ; a total of 17,379 patients with preoperative sinus rhythm ( SR ) who underwent cardiac surgery were included , of which 4984 ( 28.7 % ) had developed postoperative AF for any length of time . After propensity matching for the preoperative characteristics between the two groups ; the group with AF and the group who remained in SR , postoperative complications , in-hospital mortality , mid-term survival rate ( five years ) , and long-term survival rate ( 10 years ) were compared . RESULTS Before and after adjusting for the preoperative characteristics and type of the operation , postoperative complications , such as renal failure , surgical wound infection , stroke and myocardial infa rct ion were significantly higher in the AF group compared to the SR group ( P < 0.001 ) . Inotropic support , use of intra-aortic balloon pump , and ventilation time were also considerably higher in the AF patients ( P < 0.001 ) . In-hospital mortality was also higher in the AF group . Likewise , 30-day , mid-term and long-term mortality rates were found to be considerably higher in the AF group . CONCLUSIONS Despite all the modern anti-arrhythmic drugs , the incidence of AF remains unchanged . Patients who develop AF postcardiac surgery show a significantly worse outcome compared to those without AF . This study also highlights the importance of ant 
    Output:
    
Meta- analysis showed that the number of preoperative hypertension patients in POAF group was significantly higher ( P < 0.05 ) , while we found that there are no significant differences between two groups in Asia patients by subgroup analysis , which is in contrast to other outcomes .
Preoperative hypertension and preoperative antihypertensive medication in patients undergoing cardiac operations seem to be associated with higher risk of POAF