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: AIMS In congestive heart failure ( CHF ) patients with persistent atrial fibrillation ( AF ) , direct current cardioversion ( DCC ) may reveal participation of tachycardiamediated process to left ventricular ( LV ) dysfunction by restoring sinus rhythm ( SR ) . However , if DCC fails to restore SR , patients ' management remains challenging . The aim of the study was to assess the AF catheter ablation benefit in a selected group of CHF patients with LV ejection fraction ( LVEF ) < 40 % and persistent AF unresponsive to DCC , in whom a tachycardia-mediated process is thought to be predominant . METHODS AND RESULTS Between January 2008 and September 2011 , among 129 CHF patients with persistent AF referred to our institution , 34 ( 63.8 ± 9-year old , 24 men ) presented AF refractory to DCC with an estimated high likelihood of tachycardia-mediated LV dysfunction according to a specific set of criteria . These 34 patients underwent stepwise AF ablation and were closely followed up . After a mean 1.9 AF ablation procedures per patient and 17.6 ± 7 months after the last procedure , all patients were in SR . The New York Heart Association class improved from 2.8 ± 0.3 to 1 ± 0.2 ( P < 0.001 ) and the LVEF increased from 30.4 ± 6 to 54.6 ± 6 % ( P < 0.0001 ) after 3 - 6 months of SR , with a persistent benefit as long as the SR was maintained . CONCLUSION Atrial fibrillation catheter ablation in selected CHF patients with persistent AF refractory to DCC and without any other evidence for secondary LV dysfunction leads to a substantial LVEF improvement in the majority of them . However , redo procedures are frequent in order to achieve mid-term SR maintenance AIMS During radiofrequency ( RF ) delivery , lesion volume is highly dependent on contact force ( CF ) . It has recently been shown that changes of bipolar electrogram ( EGM ) predict transmurality . We hypothesized that there is a correlation between CF and EGM criteria of transmural lesion ( TL ) during RF . METHODS AND RESULTS We prospect ively studied consecutive 512 RF applications from atrial fibrillation ablation procedures .  A force-sensing ablation catheter ( Tacticath ( ® ) , Endosense ) was used to continuously measure CF and force-time integral ( FTI ) during each RF application . Distal bipolar EGM was analysed before , during , and after each RF application . Depending on initial EGM morphology , transmurality of lesions was defined by : ( i ) disappearance of the positivity after RF when there was QR morphology , ( ii ) diminution > 75 % of the positivity when there was QRS morphology , or ( iii ) disappearance of the R ' positivity when there was RSR ' morphology . Electrogram criteria were vali date d by electrophysiologists blinded to force measurements . Force-time integral was higher in TL than in non-transmural lesions ( NTLs ) : 652 ± 248 vs. 212 ± 140 gs ( P < 0.001 ) . Mean CF per RF pulse was higher in TL than in NTL : 26.3 ± 12.5 vs. 11.3 ± 10.3 g ( P < 0.001 ) . The best cut-off to predict TL was an FTI ≥ 392 gs [ sensitivity 0.89 , specificity ( Sp ) 0.93 , positive predictive value ( PPV ) 0.98 , and negative predictive value 0.67 ] and a higher FTI ( > 700 gs ) warrants transmurality of RF atrial lesions ( 100 % Sp and PPV ) . CONCLUSION Contact force and FTI during RF are correlated with TL . During RF delivery , a target FTI > 392 gs can be used as an endpoint Small , single-center studies suggest that catheter ablation of atrial fibrillation ( AF )  can improve ventricular function and reduce symptoms in patients with left ventricular ( LV ) dysfunction . However , ablation has not been compared with a pharmacologic strategy for AF . The authors evaluated patients with AF and symptomatic LV dysfunction ( ejection fraction < or = 45 % ) referred for pulmonary vein isolation ( PVI ) . They compared these patients with a matched cohort treated medically for AF and LV dysfunction via a retrospective case-control method . Fifteen patients ( 14 men , 56+/-11 years , 10 [ 67 % ] paroxysmal AF ) with AF for 4+/-3 years underwent PVI .  Baseline ejection fraction was 37%+/-6 % and New York Heart Association ( NYHA ) class was 2.0+/-1.0 . Fifteen controls ( 13 men , 63+/-14 years , 11 [ 73 % ] paroxysmal AF ) with AF for 5+/-4 years were treated medically for AF . Baseline ejection fraction was 34%+/-11 % and NYHA class was 2.0+/-0.7 . The groups were similar in all respects . During a follow-up of 16+/-13 months after complete PVI , ejection fraction improved ( P=.001 ) to 50%+/-13 % and normalized in 8 patients ( 53 % ) . NYHA class improved to 1.3+/-0.5 ( P=.01 ) . In the medically treated group , after follow-up of 16+/-12 months , no improvement in ejection fraction ( 36%+/-12 % ) or NYHA class ( 1.8+/-0.7 ) was seen . Compared with pharmacologic therapy , PVI significantly improved LV function and NYHA class in patients with AF and symptomatic LV dysfunction . These provocative findings provide potent rationale for a r and omized clinical trial comparing ablation with pharmacologic therapy OBJECTIVES This study sought to investigate the efficacy and safety of catheter ablation for atrial fibrillation ( AF ) in patients with heart failure with preserved ejection fraction ( HFPEF ) . BACKGROUND AF is a precipitating factor for clinical deterioration of HFPEF . METHODS Catheter ablation for AF was performed in a consecutive 74 patients with compensated HFPEF ( left ventricular [ LV ] ejection fraction > 50 % ) . AF-free probability after catheter ablation and factors relating to maintenance of sinus rhythm were investigated . LV strain and strain rate were assessed by echocardiography at baseline and over 12 months after ablation . RESULTS During a 34 ± 16-month follow-up period , single- and multiple-procedure drug-free success rates were 27 % ( n = 20 ) and 45 % ( n = 33 ) , respectively . Multiple procedures and pharmaceutically assisted success rate was 73 % ( n = 54 ) . No major complications occurred during follow-up . Multivariate Cox regression analyses revealed that AF type ( other than long-st and ing persistent AF ) and lack of hypertension were independently associated with maintenance of sinus rhythm ( hazard ratio [ HR ] : 1.81 , 95 % confidence interval [ CI ] : 1.03 to 3.17 , p = 0.04 ; HR : 0.49 , 95 % CI : 0.24 to 0.96 , p = 0.04 , respectively ) . LV systolic indices ( LV ejection fraction , LV strain/strain rate at systole ) and diastolic indices ( E/E ' , ratio of LV strain rate at diastole with early transmitral flow ) were improved only in patients maintaining sinus rhythm at follow-up . CONCLUSIONS Our results suggest that AF can be effectively and safely treated with a composite of repeat procedures and pharmaceuticals in patients with HFPEF . However , the current study was a single-arm analysis ; therefore , larger r and omized control studies are needed to verify the benefit of AF ablation in this cohort OBJECTIVES We aim ed to determine the safety and efficacy of pulmonary vein isolation ( PVI ) in atrial fibrillation ( AF ) patients with impaired left ventricular ( LV ) systolic function . BACKGROUND To date , PVI has been performed primarily in patients with normal LV function . Yet , many AF patients have impaired LV systolic function . The outcomes of PVI in patients with impaired LV systolic function are unknown . METHODS We included 377 consecutive patients undergoing PVI between December 2000 and January 2003 . Ninety-four patients had impaired LV function ( ejection fraction [ EF ] < 40 % ) , and they comprised the study group . The control group was the remaining 283 patients who had a normal EF . End points included AF recurrence and changes in EF and quality of life ( QoL ) . RESULTS Mean EF was 36 % in our study group , compared with 54 % in controls . After initial PVI , 73 % of patients with impaired EF and 87 % of patients with normal EF were free of AF recurrence at 14 + /- 6 months ( p = 0.03 ) . In the study group , there was a nonsignificant increase in EF of 4.6 % and significant improvement in QoL. Complication rates were low and included a 1 % risk of pulmonary vein stenosis . CONCLUSIONS Although the AF recurrence rate after initial PVI in impaired EF patients was higher than in normal EF subjects , nearly three-fourths of patients with impaired EF remained AF-free . Although our sample size was nonr and omized , our results suggest PVI may be a feasible therapeutic option in AF patients with impaired EF . R and omized studies with more patients and longer follow-up are warranted Atrial fibrillation ( AF ) represents the most common sustained cardiac arrhythmia in patients with heart failure ( HF ) . AF in HF patients is associated with worsening of symptoms and also results in a substantial increase in mortality . Although HF patients in sinus rhythm have a better outcome than patients with AF , several r and omized studies investigating pharmacological rhythm control versus rate control have shown no advantage of one strategy over the other in terms of patient outcomes . Catheter-based ablation therapy is a newer therapeutic option with a rapidly evolving and changing role in the management of this arrhythmia . In the present review , the authors discuss the epidemiology , pathophysiology and prognostic significance of AF in patients with HF . Exclusively addressed are studies investigating catheter-based ablation for rhythm-control and rate-control therapies in the management of AF in HF patients Background and Purpose — More than 2 million Americans have atrial fibrillation , and without antithrombotic therapy , their stroke rate is increased 5-fold . In r and omized controlled trials , warfarin prevented 65 % of ischemic strokes ( hazard ratio [ HR ] , 0.35 ; 95 % CI , 0.26 to 0.48 ) compared with no antithrombotic therapy . However , the effectiveness of warfarin therapy outside of clinical trials is unknown , especially in black and Hispanic population s. Our goal was to quantify use of warfarin therapy , frequency of International Normalized Ratio monitoring , and effectiveness for stroke prophylaxis in Medicare beneficiaries with atrial fibrillation . Methods — This was a cohort study of Medicare beneficiaries with atrial fibrillation who were hospitalized between March 1998 and April 1999 in all 50 US states . The primary outcome was incident hospitalizations for ischemic stroke based on vali date d International Classification of Diseases , 9th Revision , Clinical Modification codes . Results — Two thirds of ideal anticoagulation c and i date s were prescribed warfarin on hospital discharge . In unadjusted analyses , the stroke rates per 100 patient years of warfarin therapy were 5.2 in ( non-Hispanic ) white Medicare beneficiaries , 10.6 in black beneficiaries , and 12.2 in Hispanic beneficiaries . After adjusting for comorbid conditions , warfarin prescription was more frequent and monitoring more regular in white Medicare beneficiaries than in black or Hispanic beneficiaries ( P<0.0001 ) . Warfarin use was associated with 35 % fewer ischemic strokes ( HR , 0.65 ; 95 % CI , 0.55 to 0.76 ) compared with no antithrombotic therapy but was less effective in black and Hispanic beneficiaries ( P for interaction=0.048 ) . Conclusions — The use , monitoring , and effectiveness of warfarin therapy are suboptimal in Medicare beneficiaries , especially in black and Hispanic beneficiaries BACKGROUND Transcatheter left atrial appendage ( LAA ) ligation may represent an alternative to oral anticoagulation for stroke prevention in atrial fibrillation . OBJECTIVES This study sought to assess the early safety and efficacy of transcatheter ligation of the LAA for stroke prevention in atrial fibrillation . METHODS This was a retrospective , multicenter study of consecutive patients undergoing LAA ligation with the Lariat device at 8 U.S. sites . The primary endpoint was procedural success , defined as device success ( suture deployment and < 5 mm leak by post-procedure transesophageal echocardiography ) , and no major complication at discharge ( death , myocardial infa rct ion , stroke , Bleeding Academic Research Consortium bleeding type 3 or greater , or cardiac surgery ) . Post-discharge management was per operator discretion . RESULTS A total of 154 patients were enrolled .  Median CHADS2 
    Output:
    
agent
RECENT FINDINGS Several r and omized control trials and systematic review s demonstrate the safety and efficacy of atrial fibrillation ablation in patients with heart failure and left ventricular systolic dysfunction .
In multiple trials , these patients have shown clinical benefit from atrial fibrillation ablation including improved left ventricular systolic function , quality of life , and clinical heart failure symptoms .
SUMMARY Atrial fibrillation ablation in heart failure patients remains well tolerated with an overall efficacy comparable to atrial fibrillation ablation in patients without heart failure .
There is consistent evidence for the clinical benefit of atrial fibrillation ablation in heart failure patients with left ventricular systolic dysfunction and limited evidence for atrial fibrillation ablation in heart failure patients with preserved ejection fraction .
Currently , there is insufficient data regarding the safety and efficacy of left atrial appendage closure devices in heart failure patients
***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: AIMS In congestive heart failure ( CHF ) patients with persistent atrial fibrillation ( AF ) , direct current cardioversion ( DCC ) may reveal participation of tachycardiamediated process to left ventricular ( LV ) dysfunction by restoring sinus rhythm ( SR ) . However , if DCC fails to restore SR , patients ' management remains challenging . The aim of the study was to assess the AF catheter ablation benefit in a selected group of CHF patients with LV ejection fraction ( LVEF ) < 40 % and persistent AF unresponsive to DCC , in whom a tachycardia-mediated process is thought to be predominant . METHODS AND RESULTS Between January 2008 and September 2011 , among 129 CHF patients with persistent AF referred to our institution , 34 ( 63.8 ± 9-year old , 24 men ) presented AF refractory to DCC with an estimated high likelihood of tachycardia-mediated LV dysfunction according to a specific set of criteria . These 34 patients underwent stepwise AF ablation and were closely followed up . After a mean 1.9 AF ablation procedures per patient and 17.6 ± 7 months after the last procedure , all patients were in SR . The New York Heart Association class improved from 2.8 ± 0.3 to 1 ± 0.2 ( P < 0.001 ) and the LVEF increased from 30.4 ± 6 to 54.6 ± 6 % ( P < 0.0001 ) after 3 - 6 months of SR , with a persistent benefit as long as the SR was maintained . CONCLUSION Atrial fibrillation catheter ablation in selected CHF patients with persistent AF refractory to DCC and without any other evidence for secondary LV dysfunction leads to a substantial LVEF improvement in the majority of them . However , redo procedures are frequent in order to achieve mid-term SR maintenance AIMS During radiofrequency ( RF ) delivery , lesion volume is highly dependent on contact force ( CF ) . It has recently been shown that changes of bipolar electrogram ( EGM ) predict transmurality . We hypothesized that there is a correlation between CF and EGM criteria of transmural lesion ( TL ) during RF . METHODS AND RESULTS We prospect ively studied consecutive 512 RF applications from atrial fibrillation ablation procedures .  A force-sensing ablation catheter ( Tacticath ( ® ) , Endosense ) was used to continuously measure CF and force-time integral ( FTI ) during each RF application . Distal bipolar EGM was analysed before , during , and after each RF application . Depending on initial EGM morphology , transmurality of lesions was defined by : ( i ) disappearance of the positivity after RF when there was QR morphology , ( ii ) diminution > 75 % of the positivity when there was QRS morphology , or ( iii ) disappearance of the R ' positivity when there was RSR ' morphology . Electrogram criteria were vali date d by electrophysiologists blinded to force measurements . Force-time integral was higher in TL than in non-transmural lesions ( NTLs ) : 652 ± 248 vs. 212 ± 140 gs ( P < 0.001 ) . Mean CF per RF pulse was higher in TL than in NTL : 26.3 ± 12.5 vs. 11.3 ± 10.3 g ( P < 0.001 ) . The best cut-off to predict TL was an FTI ≥ 392 gs [ sensitivity 0.89 , specificity ( Sp ) 0.93 , positive predictive value ( PPV ) 0.98 , and negative predictive value 0.67 ] and a higher FTI ( > 700 gs ) warrants transmurality of RF atrial lesions ( 100 % Sp and PPV ) . CONCLUSION Contact force and FTI during RF are correlated with TL . During RF delivery , a target FTI > 392 gs can be used as an endpoint Small , single-center studies suggest that catheter ablation of atrial fibrillation ( AF )  can improve ventricular function and reduce symptoms in patients with left ventricular ( LV ) dysfunction . However , ablation has not been compared with a pharmacologic strategy for AF . The authors evaluated patients with AF and symptomatic LV dysfunction ( ejection fraction < or = 45 % ) referred for pulmonary vein isolation ( PVI ) . They compared these patients with a matched cohort treated medically for AF and LV dysfunction via a retrospective case-control method . Fifteen patients ( 14 men , 56+/-11 years , 10 [ 67 % ] paroxysmal AF ) with AF for 4+/-3 years underwent PVI .  Baseline ejection fraction was 37%+/-6 % and New York Heart Association ( NYHA ) class was 2.0+/-1.0 . Fifteen controls ( 13 men , 63+/-14 years , 11 [ 73 % ] paroxysmal AF ) with AF for 5+/-4 years were treated medically for AF . Baseline ejection fraction was 34%+/-11 % and NYHA class was 2.0+/-0.7 . The groups were similar in all respects . During a follow-up of 16+/-13 months after complete PVI , ejection fraction improved ( P=.001 ) to 50%+/-13 % and normalized in 8 patients ( 53 % ) . NYHA class improved to 1.3+/-0.5 ( P=.01 ) . In the medically treated group , after follow-up of 16+/-12 months , no improvement in ejection fraction ( 36%+/-12 % ) or NYHA class ( 1.8+/-0.7 ) was seen . Compared with pharmacologic therapy , PVI significantly improved LV function and NYHA class in patients with AF and symptomatic LV dysfunction . These provocative findings provide potent rationale for a r and omized clinical trial comparing ablation with pharmacologic therapy OBJECTIVES This study sought to investigate the efficacy and safety of catheter ablation for atrial fibrillation ( AF ) in patients with heart failure with preserved ejection fraction ( HFPEF ) . BACKGROUND AF is a precipitating factor for clinical deterioration of HFPEF . METHODS Catheter ablation for AF was performed in a consecutive 74 patients with compensated HFPEF ( left ventricular [ LV ] ejection fraction > 50 % ) . AF-free probability after catheter ablation and factors relating to maintenance of sinus rhythm were investigated . LV strain and strain rate were assessed by echocardiography at baseline and over 12 months after ablation . RESULTS During a 34 ± 16-month follow-up period , single- and multiple-procedure drug-free success rates were 27 % ( n = 20 ) and 45 % ( n = 33 ) , respectively . Multiple procedures and pharmaceutically assisted success rate was 73 % ( n = 54 ) . No major complications occurred during follow-up . Multivariate Cox regression analyses revealed that AF type ( other than long-st and ing persistent AF ) and lack of hypertension were independently associated with maintenance of sinus rhythm ( hazard ratio [ HR ] : 1.81 , 95 % confidence interval [ CI ] : 1.03 to 3.17 , p = 0.04 ; HR : 0.49 , 95 % CI : 0.24 to 0.96 , p = 0.04 , respectively ) . LV systolic indices ( LV ejection fraction , LV strain/strain rate at systole ) and diastolic indices ( E/E ' , ratio of LV strain rate at diastole with early transmitral flow ) were improved only in patients maintaining sinus rhythm at follow-up . CONCLUSIONS Our results suggest that AF can be effectively and safely treated with a composite of repeat procedures and pharmaceuticals in patients with HFPEF . However , the current study was a single-arm analysis ; therefore , larger r and omized control studies are needed to verify the benefit of AF ablation in this cohort OBJECTIVES We aim ed to determine the safety and efficacy of pulmonary vein isolation ( PVI ) in atrial fibrillation ( AF ) patients with impaired left ventricular ( LV ) systolic function . BACKGROUND To date , PVI has been performed primarily in patients with normal LV function . Yet , many AF patients have impaired LV systolic function . The outcomes of PVI in patients with impaired LV systolic function are unknown . METHODS We included 377 consecutive patients undergoing PVI between December 2000 and January 2003 . Ninety-four patients had impaired LV function ( ejection fraction [ EF ] < 40 % ) , and they comprised the study group . The control group was the remaining 283 patients who had a normal EF . End points included AF recurrence and changes in EF and quality of life ( QoL ) . RESULTS Mean EF was 36 % in our study group , compared with 54 % in controls . After initial PVI , 73 % of patients with impaired EF and 87 % of patients with normal EF were free of AF recurrence at 14 + /- 6 months ( p = 0.03 ) . In the study group , there was a nonsignificant increase in EF of 4.6 % and significant improvement in QoL. Complication rates were low and included a 1 % risk of pulmonary vein stenosis . CONCLUSIONS Although the AF recurrence rate after initial PVI in impaired EF patients was higher than in normal EF subjects , nearly three-fourths of patients with impaired EF remained AF-free . Although our sample size was nonr and omized , our results suggest PVI may be a feasible therapeutic option in AF patients with impaired EF . R and omized studies with more patients and longer follow-up are warranted Atrial fibrillation ( AF ) represents the most common sustained cardiac arrhythmia in patients with heart failure ( HF ) . AF in HF patients is associated with worsening of symptoms and also results in a substantial increase in mortality . Although HF patients in sinus rhythm have a better outcome than patients with AF , several r and omized studies investigating pharmacological rhythm control versus rate control have shown no advantage of one strategy over the other in terms of patient outcomes . Catheter-based ablation therapy is a newer therapeutic option with a rapidly evolving and changing role in the management of this arrhythmia . In the present review , the authors discuss the epidemiology , pathophysiology and prognostic significance of AF in patients with HF . Exclusively addressed are studies investigating catheter-based ablation for rhythm-control and rate-control therapies in the management of AF in HF patients Background and Purpose — More than 2 million Americans have atrial fibrillation , and without antithrombotic therapy , their stroke rate is increased 5-fold . In r and omized controlled trials , warfarin prevented 65 % of ischemic strokes ( hazard ratio [ HR ] , 0.35 ; 95 % CI , 0.26 to 0.48 ) compared with no antithrombotic therapy . However , the effectiveness of warfarin therapy outside of clinical trials is unknown , especially in black and Hispanic population s. Our goal was to quantify use of warfarin therapy , frequency of International Normalized Ratio monitoring , and effectiveness for stroke prophylaxis in Medicare beneficiaries with atrial fibrillation . Methods — This was a cohort study of Medicare beneficiaries with atrial fibrillation who were hospitalized between March 1998 and April 1999 in all 50 US states . The primary outcome was incident hospitalizations for ischemic stroke based on vali date d International Classification of Diseases , 9th Revision , Clinical Modification codes . Results — Two thirds of ideal anticoagulation c and i date s were prescribed warfarin on hospital discharge . In unadjusted analyses , the stroke rates per 100 patient years of warfarin therapy were 5.2 in ( non-Hispanic ) white Medicare beneficiaries , 10.6 in black beneficiaries , and 12.2 in Hispanic beneficiaries . After adjusting for comorbid conditions , warfarin prescription was more frequent and monitoring more regular in white Medicare beneficiaries than in black or Hispanic beneficiaries ( P<0.0001 ) . Warfarin use was associated with 35 % fewer ischemic strokes ( HR , 0.65 ; 95 % CI , 0.55 to 0.76 ) compared with no antithrombotic therapy but was less effective in black and Hispanic beneficiaries ( P for interaction=0.048 ) . Conclusions — The use , monitoring , and effectiveness of warfarin therapy are suboptimal in Medicare beneficiaries , especially in black and Hispanic beneficiaries BACKGROUND Transcatheter left atrial appendage ( LAA ) ligation may represent an alternative to oral anticoagulation for stroke prevention in atrial fibrillation . OBJECTIVES This study sought to assess the early safety and efficacy of transcatheter ligation of the LAA for stroke prevention in atrial fibrillation . METHODS This was a retrospective , multicenter study of consecutive patients undergoing LAA ligation with the Lariat device at 8 U.S. sites . The primary endpoint was procedural success , defined as device success ( suture deployment and < 5 mm leak by post-procedure transesophageal echocardiography ) , and no major complication at discharge ( death , myocardial infa rct ion , stroke , Bleeding Academic Research Consortium bleeding type 3 or greater , or cardiac surgery ) . Post-discharge management was per operator discretion . RESULTS A total of 154 patients were enrolled .  Median CHADS2 
    Output:
    