human
***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 In a previous study of 225 patients with sick-sinus syndrome r and omised to either single-chamber atrial pacing ( n=110 ) or single-chamber ventricular pacing ( n=115 ) , we found that after a mean follow-up of 3.3 years , atrial pacing was associated with significantly less atrial fibrillation and thromboembolism whereas there was no significant difference in mortality and heart failure between the two groups . We aim ed to find out whether this beneficial effect of atrial pacing is maintained during extended follow-up of up to 8 years . METHODS Follow-up visits for all patients were at 3 months , 12 months , then once a year at which patients had a physical examination , ECG recording , and pacemaker check-up . Endpoints were mortality , cardiovascular death , atrial fibrillation , thromboembolic events , heart failure , and atrioventricular block . Data was analysed on Dec 31 , 1996 . FINDINGS At long-term follow-up , 39 patients from the atrial group had died versus 57 from the ventricular group ( relative risk 0.66 [ 95 % CI 0.44 - 0.99 ] ; p=0.045 ) . 19 patients from the atrial group and 39 patients from the ventricular group died from a cardiovascular cause ( 0.47 [ 0.27 - 0.82 ] ; p=0.0065 ) . The cumulative incidences of atrial fibrillation and chronic atrial fibrillation were also significantly lower in the atrial group than in the ventricular group ( 0.54 [ 0.33 - 0.89 ] , p=0.012 and 0.35 [ 0.16 - 0.76 ] , p=0.004 , respectively ) . Thromboembolic events occurred in 13 patients in the atrial group and 26 in the ventricular group ( 0.47 [ 0.24 - 0.92 ] , p=0.023 ) . Heart failure was less severe in the atrial group than in the ventricular group ( p<0.05 ) . In multivariate analysis , atrial pacing was significantly associated with freedom from thromboembolic events ( 0.47 [ 0.24 - 0.92 ] , p=0.028 ) and survival from cardiovascular death ( 0.52 [ 0.30 - 0.91 ] , p=0.022 ) , but no longer with overall survival ( 0.71 [ 0.46 - 1.08 ] , p=0.11 ) or chronic atrial fibrillation ( 0.45 [ 0.20 - 1.05 ] , p=0.063 ) . Atrioventricular block occurred in four patients in the atrial group ( 0.6 % annual risk ) . INTERPRETATION The beneficial effect of atrial pacing found in our previous study is enhanced substantially over time . Patients with sick-sinus syndrome should be treated with an atrial rather than ventricular-pacing system because after long-term follow-up , atrial pacing is associated with a significantly higher survival , less atrial fibrillation , fewer thromboembolic complications , less heart failure , and a low-risk of atrioventricular block Background —Some current pacing systems can automatically detect and record atrial tachyarrhythmias that may be asymptomatic . We prospect ively studied a 312-patient ( pt ) subgroup of MOST ( MOde Selection Trial ) , a 2010-patient , 6-year r and omized trial of DDDR versus VVIR pacing in sinus node dysfunction ( SND ) . The purpose of the study was to correlate atrial high rate events ( AHREs ) detected by pacemaker diagnostics with clinical outcomes . Methods and Results —Pacemakers were programmed to log an AHRE when the atrial rate was > 220 bpm for 10 consecutive beats . Analysis was confined to patients with at least 1 AHRE duration exceeding 5 minutes . The 312 patients were median age 74 years , 55 % female , and 60 % had a history of SVT . 160 of 312 ( 51.3 % ) patients enrolled had at least 1 AHRE > 5 minutes duration over median follow-up of 27 months . Cox proportional hazards analysis assessed the relationship of AHREs with clinical events , adjusting for prognostic variables and baseline covariates . The presence of any AHRE was an independent predictor of the following : total mortality ( hazard ratio AHRE versus no AHRE and 95 % confidence intervals=2.48 [ 1.25 , 4.91 ] , P = 0.0092 ) ; death or nonfatal stroke ( 2.79 [ 1.51 , 5.15 ] , P = 0.0011 ) ; and atrial fibrillation ( 5.93 [ 2.88 , 12.2 ] , P = 0.0001 ) . There was no significant effect of pacing mode on the presence or absence of AHREs . Conclusions —AHRE detected by pacemakers in patients with SND identify patients that are more than twice as likely to die or have a stroke , and 6 times as likely to develop atrial fibrillation as similar patients without AHRE Background — Atrial fibrillation ( AF ) after cardiac surgery is associated with increased risk of complications , length of stay , and cost of care . Observational evidence suggests that patients who have undergone previous statin therapy have a lower incidence of postoperative AF . We tested this observation in a r and omized , controlled trial . Methods and Results — Two hundred patients undergoing elective cardiac surgery with cardiopulmonary bypass , without previous statin treatment or history of AF , were enrolled . Patients were r and omized to atorvastatin ( 40 mg/d , n=101 ) or placebo  ( n=99 ) starting 7 days before operation . The primary end point was incidence of postoperative AF ; secondary end points were length of stay , 30-day major adverse cardiac and cerebrovascular events , and postoperative C-reactive protein ( CRP ) variations . Atorvastatin significantly reduced the incidence of AF versus placebo ( 35 % versus 57 % , P=0.003 ) . Accordingly , length of stay was longer in the placebo versus atorvastatin arm ( 6.9±1.4 versus 6.3±1.2 days , P=0.001 ) . Peak CRP levels were lower in patients without AF ( P=0.01 ) , irrespective of r and omization assignment . Multivariable analysis showed that atorvastatin treatment conferred a 61 % reduction in risk of AF ( odds ratio 0.39 , 95 % confidence interval 0.18 to 0.85 , P=0.017 ) , whereas high postoperative CRP levels were associated with increased risk ( odds ratio 2.0 , 95 % confidence interval 1.2 to 7.0 , P=0.01 ) . The incidence of major adverse cardiac and cerebrovascular events at 30 days was similar in the 2 arms . Conclusions — Treatment with atorvastatin 40 mg/d , initiated 7 days before surgery , significantly reduces the incidence of postoperative AF after elective cardiac surgery with cardiopulmonary bypass and shortens hospital stay . These results may influence practice patterns with regard to adjuvant pharmacological therapy before cardiac surgery BACKGROUND Increasing evidence suggests that atrial fibrillation ( AF ) is an inflammatory disease . Statins is an anti-inflammatory agent . The present study was conducted to test the efficacy of atorvastatin in preventing paroxysmal AF or atrial high rate episodes ( AHEs ) in patients with bradyarrhythmias and implantation of an atrial-based or dual-chamber pacemaker . METHODS The effect of atorvastatin on time to the first attack of AF or AHE ( > or = 180 per minute and > or = 1 or 10 minutes ) , which was accurately detected by pacemaker interrogation , was evaluated in an open-label prospect i ve r and omized design for 1 year of follow-up . RESULTS Fifty-two patients ( 23 males , 70 + /- 13 years old ) were r and omized to the  statin group ( atorvastatin 20 mg/d ) and 54 ( 25 males , 72 + /- 13 years old ) to the  nonstatin group . Event-free survivals from AHE > or = 1 minute were not significantly different between the 2 groups ( log-rank P = .410 ) . However , patients in the nonstatin group were more likely to develop AHE > or = 10 minutes than those in the statin group ( log-rank P = .028 ) . Atrial high rate episode > or = 10 minutes occurred in 3 ( 5.8 % ) of 51 patients in the statin group after 1 year of follow-up , and 10 ( 19.2 % ) of 52 patients ( odds ratio 0.26 , P = .041 ) in the nonstatin group . The mean left atrial volume of the statin group was significantly lower than that of the nonstatin group at the end of follow-up ( 39.7 + /- 1.7 vs 43.7 + /- 1.9 mL , P < .0001 ) . CONCLUSIONS The present study demonstrated the efficacy of atorvastatin in preventing significant AF ( > or = 10 minutes ) and left atrial enlargement in patients with bradyarrhythmias and implantation of a pacemaker BACKGROUND Dual-chamber ( atrioventricular ) and single-chamber ( ventricular ) pacing are alternative treatment approaches for sinus-node dysfunction that causes clinical ly significant bradycardia . However , it is unknown which type of pacing results in the better outcome . METHODS We r and omly assigned a total of 2010 patients with sinus-node dysfunction to dual-chamber pacing ( 1014 patients ) or ventricular pacing ( 996 patients ) and followed them for a median of 33.1 months . The primary end point was death from any cause or nonfatal stroke . Secondary end points included the composite of death , stroke , or hospitalization for heart failure ; atrial fibrillation ; heart-failure score ; the pacemaker syndrome ; and the quality of life . RESULTS The incidence of the primary end point did not differ significantly between the dual-chamber group ( 21.5 percent ) and the ventricular-paced group ( 23.0 percent , P=0.48 ) . In patients assigned to dual-chamber pacing , the risk of atrial fibrillation was lower ( hazard ratio , 0.79 ; 95 percent confidence interval , 0.66 to 0.94 ; P=0.008 ) , and heart-failure scores were better ( P<0.001 ) . The differences in the rates of hospitalization for heart failure and of death , stroke , or hospitalization for heart failure were not significant in unadjusted analyses but became marginally significant in adjusted analyses . Dual-chamber pacing result ed in a small but measurable increase in the quality of life , as compared with ventricular pacing . CONCLUSIONS In sinus-node dysfunction , dual-chamber pacing does not improve stroke-free survival , as compared with ventricular pacing . However , dual-chamber pacing reduces the risk of atrial fibrillation , reduces signs and symptoms of heart failure , and slightly improves the quality of life . Overall , dual-chamber pacing offers significant improvement as compared with ventricular pacing BACKGROUND The epidemiology and clinical implication s of asymptomatic atrial tachyarrhythmias ( AT ) including both atrial fibrillation and flutter in pacemaker recipients with and without arrhythmia history are not well understood . The Atrial High Rate Episodes ( A-HIRATE ) in Pacemaker Patients Trial was design ed to identify and compare the incidence of AT in patients with and without previously diagnosed AT and a st and ard indication for dual chamber pacing  , and to provide useful diagnostic information for clinical management . METHODS Four hundred twenty-seven patients were implanted with a pacemaker ( Kappa 7 - 900 , Medtronic , Inc. , Minneapolis , MN , USA ) capable of detecting and storing multiple atrial high rate episodes ( AHRE ) and followed for 2 years . Group I included 331 patients without prior history of AT and Group II included 96 patients with prior AT history . RESULTS Pacemaker diagnostics appropriately detected 93 % of review ed AHRE . The rate of occurrence of first AHRE was significantly higher ( P < 0.0001 ) in Group II patients , as was average AHRE burden . The rate of first AHRE occurrence was 88.6 % for patients in Group II and 53.8 % in Group I at 24 months post-implant . The rate of AHRE occurrence was similar in both groups after the first month post-implant . The majority of stored AHRE were asymptomatic ; symptoms did not correspond to an actual AHRE in most patients . CONCLUSIONS The incidence of AT in pacemaker recipients is high . Most device-detected AHRE are asymptomatic . Prior history of AT is associated with higher arrhythmia burden . AHRE diagnostics have a high positive predictive value for identifying AT events OBJECTIVE It has been recently reported that AF is associated with tissue inflammation . Statins reduce C-reactive protein ( CRP ) levels . However , the effect of statin on atrial fibrillation ( AF ) is unclear . The purpose of the present study was to evaluate the effect 
    Output:
    
agent
Statistical heterogeneity between included studies was not detected ( chi(2 ) = 1.68 , P = 0.43 , I(2 ) = 0 % ) , although significant clinical differences were found in terms of study design , patient population s , statins use and dosage and AF-monitoring capabilities .
Statins may represent a novel treatment strategy to prevent the occurrence of AF in patients with PM , especially for those who had a PM implanted due to sinus node dysfunction .
***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 In a previous study of 225 patients with sick-sinus syndrome r and omised to either single-chamber atrial pacing ( n=110 ) or single-chamber ventricular pacing ( n=115 ) , we found that after a mean follow-up of 3.3 years , atrial pacing was associated with significantly less atrial fibrillation and thromboembolism whereas there was no significant difference in mortality and heart failure between the two groups . We aim ed to find out whether this beneficial effect of atrial pacing is maintained during extended follow-up of up to 8 years . METHODS Follow-up visits for all patients were at 3 months , 12 months , then once a year at which patients had a physical examination , ECG recording , and pacemaker check-up . Endpoints were mortality , cardiovascular death , atrial fibrillation , thromboembolic events , heart failure , and atrioventricular block . Data was analysed on Dec 31 , 1996 . FINDINGS At long-term follow-up , 39 patients from the atrial group had died versus 57 from the ventricular group ( relative risk 0.66 [ 95 % CI 0.44 - 0.99 ] ; p=0.045 ) . 19 patients from the atrial group and 39 patients from the ventricular group died from a cardiovascular cause ( 0.47 [ 0.27 - 0.82 ] ; p=0.0065 ) . The cumulative incidences of atrial fibrillation and chronic atrial fibrillation were also significantly lower in the atrial group than in the ventricular group ( 0.54 [ 0.33 - 0.89 ] , p=0.012 and 0.35 [ 0.16 - 0.76 ] , p=0.004 , respectively ) . Thromboembolic events occurred in 13 patients in the atrial group and 26 in the ventricular group ( 0.47 [ 0.24 - 0.92 ] , p=0.023 ) . Heart failure was less severe in the atrial group than in the ventricular group ( p<0.05 ) . In multivariate analysis , atrial pacing was significantly associated with freedom from thromboembolic events ( 0.47 [ 0.24 - 0.92 ] , p=0.028 ) and survival from cardiovascular death ( 0.52 [ 0.30 - 0.91 ] , p=0.022 ) , but no longer with overall survival ( 0.71 [ 0.46 - 1.08 ] , p=0.11 ) or chronic atrial fibrillation ( 0.45 [ 0.20 - 1.05 ] , p=0.063 ) . Atrioventricular block occurred in four patients in the atrial group ( 0.6 % annual risk ) . INTERPRETATION The beneficial effect of atrial pacing found in our previous study is enhanced substantially over time . Patients with sick-sinus syndrome should be treated with an atrial rather than ventricular-pacing system because after long-term follow-up , atrial pacing is associated with a significantly higher survival , less atrial fibrillation , fewer thromboembolic complications , less heart failure , and a low-risk of atrioventricular block Background —Some current pacing systems can automatically detect and record atrial tachyarrhythmias that may be asymptomatic . We prospect ively studied a 312-patient ( pt ) subgroup of MOST ( MOde Selection Trial ) , a 2010-patient , 6-year r and omized trial of DDDR versus VVIR pacing in sinus node dysfunction ( SND ) . The purpose of the study was to correlate atrial high rate events ( AHREs ) detected by pacemaker diagnostics with clinical outcomes . Methods and Results —Pacemakers were programmed to log an AHRE when the atrial rate was > 220 bpm for 10 consecutive beats . Analysis was confined to patients with at least 1 AHRE duration exceeding 5 minutes . The 312 patients were median age 74 years , 55 % female , and 60 % had a history of SVT . 160 of 312 ( 51.3 % ) patients enrolled had at least 1 AHRE > 5 minutes duration over median follow-up of 27 months . Cox proportional hazards analysis assessed the relationship of AHREs with clinical events , adjusting for prognostic variables and baseline covariates . The presence of any AHRE was an independent predictor of the following : total mortality ( hazard ratio AHRE versus no AHRE and 95 % confidence intervals=2.48 [ 1.25 , 4.91 ] , P = 0.0092 ) ; death or nonfatal stroke ( 2.79 [ 1.51 , 5.15 ] , P = 0.0011 ) ; and atrial fibrillation ( 5.93 [ 2.88 , 12.2 ] , P = 0.0001 ) . There was no significant effect of pacing mode on the presence or absence of AHREs . Conclusions —AHRE detected by pacemakers in patients with SND identify patients that are more than twice as likely to die or have a stroke , and 6 times as likely to develop atrial fibrillation as similar patients without AHRE Background — Atrial fibrillation ( AF ) after cardiac surgery is associated with increased risk of complications , length of stay , and cost of care . Observational evidence suggests that patients who have undergone previous statin therapy have a lower incidence of postoperative AF . We tested this observation in a r and omized , controlled trial . Methods and Results — Two hundred patients undergoing elective cardiac surgery with cardiopulmonary bypass , without previous statin treatment or history of AF , were enrolled . Patients were r and omized to atorvastatin ( 40 mg/d , n=101 ) or placebo  ( n=99 ) starting 7 days before operation . The primary end point was incidence of postoperative AF ; secondary end points were length of stay , 30-day major adverse cardiac and cerebrovascular events , and postoperative C-reactive protein ( CRP ) variations . Atorvastatin significantly reduced the incidence of AF versus placebo ( 35 % versus 57 % , P=0.003 ) . Accordingly , length of stay was longer in the placebo versus atorvastatin arm ( 6.9±1.4 versus 6.3±1.2 days , P=0.001 ) . Peak CRP levels were lower in patients without AF ( P=0.01 ) , irrespective of r and omization assignment . Multivariable analysis showed that atorvastatin treatment conferred a 61 % reduction in risk of AF ( odds ratio 0.39 , 95 % confidence interval 0.18 to 0.85 , P=0.017 ) , whereas high postoperative CRP levels were associated with increased risk ( odds ratio 2.0 , 95 % confidence interval 1.2 to 7.0 , P=0.01 ) . The incidence of major adverse cardiac and cerebrovascular events at 30 days was similar in the 2 arms . Conclusions — Treatment with atorvastatin 40 mg/d , initiated 7 days before surgery , significantly reduces the incidence of postoperative AF after elective cardiac surgery with cardiopulmonary bypass and shortens hospital stay . These results may influence practice patterns with regard to adjuvant pharmacological therapy before cardiac surgery BACKGROUND Increasing evidence suggests that atrial fibrillation ( AF ) is an inflammatory disease . Statins is an anti-inflammatory agent . The present study was conducted to test the efficacy of atorvastatin in preventing paroxysmal AF or atrial high rate episodes ( AHEs ) in patients with bradyarrhythmias and implantation of an atrial-based or dual-chamber pacemaker . METHODS The effect of atorvastatin on time to the first attack of AF or AHE ( > or = 180 per minute and > or = 1 or 10 minutes ) , which was accurately detected by pacemaker interrogation , was evaluated in an open-label prospect i ve r and omized design for 1 year of follow-up . RESULTS Fifty-two patients ( 23 males , 70 + /- 13 years old ) were r and omized to the  statin group ( atorvastatin 20 mg/d ) and 54 ( 25 males , 72 + /- 13 years old ) to the  nonstatin group . Event-free survivals from AHE > or = 1 minute were not significantly different between the 2 groups ( log-rank P = .410 ) . However , patients in the nonstatin group were more likely to develop AHE > or = 10 minutes than those in the statin group ( log-rank P = .028 ) . Atrial high rate episode > or = 10 minutes occurred in 3 ( 5.8 % ) of 51 patients in the statin group after 1 year of follow-up , and 10 ( 19.2 % ) of 52 patients ( odds ratio 0.26 , P = .041 ) in the nonstatin group . The mean left atrial volume of the statin group was significantly lower than that of the nonstatin group at the end of follow-up ( 39.7 + /- 1.7 vs 43.7 + /- 1.9 mL , P < .0001 ) . CONCLUSIONS The present study demonstrated the efficacy of atorvastatin in preventing significant AF ( > or = 10 minutes ) and left atrial enlargement in patients with bradyarrhythmias and implantation of a pacemaker BACKGROUND Dual-chamber ( atrioventricular ) and single-chamber ( ventricular ) pacing are alternative treatment approaches for sinus-node dysfunction that causes clinical ly significant bradycardia . However , it is unknown which type of pacing results in the better outcome . METHODS We r and omly assigned a total of 2010 patients with sinus-node dysfunction to dual-chamber pacing ( 1014 patients ) or ventricular pacing ( 996 patients ) and followed them for a median of 33.1 months . The primary end point was death from any cause or nonfatal stroke . Secondary end points included the composite of death , stroke , or hospitalization for heart failure ; atrial fibrillation ; heart-failure score ; the pacemaker syndrome ; and the quality of life . RESULTS The incidence of the primary end point did not differ significantly between the dual-chamber group ( 21.5 percent ) and the ventricular-paced group ( 23.0 percent , P=0.48 ) . In patients assigned to dual-chamber pacing , the risk of atrial fibrillation was lower ( hazard ratio , 0.79 ; 95 percent confidence interval , 0.66 to 0.94 ; P=0.008 ) , and heart-failure scores were better ( P<0.001 ) . The differences in the rates of hospitalization for heart failure and of death , stroke , or hospitalization for heart failure were not significant in unadjusted analyses but became marginally significant in adjusted analyses . Dual-chamber pacing result ed in a small but measurable increase in the quality of life , as compared with ventricular pacing . CONCLUSIONS In sinus-node dysfunction , dual-chamber pacing does not improve stroke-free survival , as compared with ventricular pacing . However , dual-chamber pacing reduces the risk of atrial fibrillation , reduces signs and symptoms of heart failure , and slightly improves the quality of life . Overall , dual-chamber pacing offers significant improvement as compared with ventricular pacing BACKGROUND The epidemiology and clinical implication s of asymptomatic atrial tachyarrhythmias ( AT ) including both atrial fibrillation and flutter in pacemaker recipients with and without arrhythmia history are not well understood . The Atrial High Rate Episodes ( A-HIRATE ) in Pacemaker Patients Trial was design ed to identify and compare the incidence of AT in patients with and without previously diagnosed AT and a st and ard indication for dual chamber pacing  , and to provide useful diagnostic information for clinical management . METHODS Four hundred twenty-seven patients were implanted with a pacemaker ( Kappa 7 - 900 , Medtronic , Inc. , Minneapolis , MN , USA ) capable of detecting and storing multiple atrial high rate episodes ( AHRE ) and followed for 2 years . Group I included 331 patients without prior history of AT and Group II included 96 patients with prior AT history . RESULTS Pacemaker diagnostics appropriately detected 93 % of review ed AHRE . The rate of occurrence of first AHRE was significantly higher ( P < 0.0001 ) in Group II patients , as was average AHRE burden . The rate of first AHRE occurrence was 88.6 % for patients in Group II and 53.8 % in Group I at 24 months post-implant . The rate of AHRE occurrence was similar in both groups after the first month post-implant . The majority of stored AHRE were asymptomatic ; symptoms did not correspond to an actual AHRE in most patients . CONCLUSIONS The incidence of AT in pacemaker recipients is high . Most device-detected AHRE are asymptomatic . Prior history of AT is associated with higher arrhythmia burden . AHRE diagnostics have a high positive predictive value for identifying AT events OBJECTIVE It has been recently reported that AF is associated with tissue inflammation . Statins reduce C-reactive protein ( CRP ) levels . However , the effect of statin on atrial fibrillation ( AF ) is unclear . The purpose of the present study was to evaluate the effect 
    Output:
    