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 The objective of this study was to investigate atrial myocardial properties through two-dimensional ( 2D ) myocardial imaging in patients with atrial fibrillation ( AF ) and its predictive role for recurrence after catheter ablation . Methods and results Echocardiographic examinations were performed in 40 patients with paroxysmal AF before catheter ablation and 40 age- and gender-matched healthy control subjects . Using a software package , bidimensional acquisitions were analyzed to measure longitudinal strain and strain rate for the left atrium ( LA ) . Systolic strain and strain rate in all eight segments , and its average values , were significantly reduced in AF patients compared to controls . During 9 months of follow-up after catheter ablation for AF , 11 of 40 AF patients had AF recurrence . AF recurrence was associated with gender , LA volume index , and average values of systolic strain and strain rate . By multivariate analysis , only average strain was an independent predictor of AF recurrence ( OR = 0.88 , 95 % CI 0.79 - 0.98 , p = 0.018 ) . Conclusions Lower systolic strain of LA was strongly associated with recurrence after catheter ablation . Thus , diverse adjunctive ablation strategies should be considered to reduce recurrence in patients with lower systolic strain AIMS The aim of this multicentre study was to determine the normal range and the clinical relevance of the myocardial function of the left atrium ( LA ) analysed by 2D speckle-tracking echocardiography ( 2DSTE ) . METHODS AND RESULTS We analysed 329 healthy adult subjects prospect ively included in 10 centres and a validation group of 377 patients with left ventricular diastolic dysfunction ( LVDD ) . LA myocardial function was analysed by LA strain rate peak during LA contraction ( LA-SRa ) and LA strain peak during LA relaxation ( LA-Strain ) . The range of values of LA myocardial function in healthy subjects was LA-SRa -2.11 ± 0.61 s(-1 ) and LA-Strain 45.5 ± 11.4 % , and the lowest expected values of these LA analyses ( calculated as -1.96 SD from the mean of healthy subjects ) were LA-SRa -0.91 s(-1 ) and LA-Strain 23.1 % . Concerning the clinical relevance of these LA myocardial analyses , LA-SRa and LA-Strain detected subtle LA dysfunction in patients with LVDD , even though LA volumetric measurements were normal . In addition , in these patients we found that the functional class ( dyspnoea-NYHA classification ) was inversely related to both LA-Strain and LA-SRa . CONCLUSION In the present multicentre study analysing a large cohort of healthy subjects and patients with LVDD , the normal range and the clinical relevance of the myocardial function of the LA using 2DSTE have been determined OBJECTIVE Since predictors of recurrence of atrial fibrillation ( AF ) after ablation procedures are poorly defined , this prospect i ve study was conducted to assess the value of left atrial ( LA ) deformation imaging with two-dimensional speckle-tracking ( 2D-ST ) to predict AF recurrences after successful ablation procedures . METHODS AND RESULTS One hundred and three consecutive patients ( age 58.1 ± 16.6 years , 72.8 % male ) with AF ( 76 paroxysmal , 27 persistent ) and 30 matched controls underwent transthoracic echocardiography and 2D-ST-LA-deformation analysis with assessment of LA-radial and LA-longitudinal strain ( Sr , Sl ) , and velocities derived from the apical 4- and 2-chamber views ( 4CV , 2CV ) . AF recurrence was assessed during 6 months of follow-up . For determination of AF-related LA changes , AF patients were compared to controls and patients with AF recurrences after ablation procedures ( n = 30 , 29.1 % ) were compared with patients who maintained sinus rhythm ( n = 73 , 70.9 % ) . Atrial deformation capabilities were significantly reduced ( P < 0.0005 ) in patients with AF ( 4CVSl 17.8 ± 13.5 % ; 4CVSr 22.3 ± 14.9 % ; 4CV-velocities 2.53 ± 0.97 seconds ) when compared with controls ( 4CVSl 31.3 ± 12.4 % ; 4CVSr 30.3 ± 9.1 % ; 4CV-velocities 3.48 ± 1.01 cm/s ) . Independent predictors for AF recurrence after ablation procedures were 2CV-LA-global-strain ( Sr , P = 0.03 ; Sl , P = 0.003 ) , 4CV-LA-gobal-strain ( Sr , P = 0.03 ; Sl , P = 0.02 ) , and regional LA-septal wall-Sl ( P = 0.008 ) . LA-global-strain parameters were superior to regional LA function analysis for the prediction of AF recurrences , with cutoff values ( cov ) , hazard ratios ( HR ) , positive and negative predictive values ( PPV , NPV ) were : 4CVSl cov , 10.79 % ( HR 27.8 , P < 0.0005 ; PPV 78.8 % , NPV 93.9 % ) , 4CVSr cov , -16.65 % ( HR 24.8 , P < 0.0005 ; PPV 69.4 % , NPV 96.6 % ) , 2CVSl cov , 12.31 % ( HR 22.7 , P < 0.0005 ; PPV 75.8 % , NPV 95.3 % ) , and 2CVSr cov , -14.9 % ( HR 12.9 , P < 0.0005 ; PPV 64.3 % , NPV 93.2 % ) . CONCLUSION Compared with controls , AF itself seems to decrease LA deformation capabilities . The assessment of global LA strain with 2D-ST identifies patients with high risk for AF recurrence after ablation procedures . This imaging technique may help to improve therapeutic guiding for patients with AF The incremental value of left atrial ( LA ) deformation analysis by speckle tracking echocardiography compared with LA volume or LA ejection fraction as a cardiovascular risk marker has not been evaluated prospect ively . We sought to compare LA function by speckle tracking echocardiography to other conventional LA parameters for prediction of adverse cardiovascular outcomes . This prospect i ve study included 312 adults ( mean age 71 ± 6 years , 56 % men ) in sinus rhythm who were followed for development of first atrial fibrillation , congestive heart failure , stroke , transient ischemic attack , myocardial infa rct ion , coronary revascularization , and cardiovascular death .  Global peak atrial longitudinal strain ( PALS ) by speckle tracking echocardiography was measured in all subjects by averaging all atrial segments . Left atrium was assessed with biplane LA volume , LA ejection fraction , 4-chamber LA area , and M-mode dimension . Of 312 subjects at baseline , 43 had 61 new events during a mean follow-up of 3.1 ± 1.4 years . All LA parameters , traditional parameters , and parameters derived by speckle tracking echocardiography were independently predictive of combined outcomes ( p < 0.0001 for all comparisons ) . Overall performance for prediction of cardiovascular events was greatest for global PALS ( area under receiver operator characteristic curve : global PALS 0.83 , indexed LA volume 0.71 , LA ejection fraction 0.69 , LA area 0.64 , LA diameter 0.59 ) . A grade d association between degree of LA enlargement and risk of cardiovascular events was evident only for global PALS and indexed LA volume . In conclusion , global PALS is a strong and independent predictor of cardiovascular events and appears to be superior to conventional parameters of LA analysis BACKGROUND Given the potential complications of atrial fibrillation ( AF ) recurrence after ablation , better predictors of the effectiveness of the procedure are necessary to guide patient selection . AIM This prospect i ve study was conducted to evaluate the clinical relevance of global left atrial longitudinal strain ( GLAS ) and AF recurrence after catheter ablation . METHODS In 115 consecutive patients with AF ( persistent , n=62 ; paroxysmal , n=53 ) ,  transthoracic echocardiography was performed before catheter ablation to assess baseline left atrial mechanical function using speckle tracking echocardiography ( STE ) . RESULTS After 12 months of follow-up , 22 ( 35.5 % ) patients in the persistent AF group and 15 ( 28.3 % ) in the paroxysmal AF group exhibited AF recurrence . In both the paroxysmal and persistent AF population s , patients with recurrence presented with significantly impaired GLAS compared with patients without recurrence . Patients with recurrence also had a significantly higher pro-B-type natriuretic peptide concentration . A receiver operator curve analysis yielded area under the curve values of 0.94 and 0.86 for paroxysmal and persistent AF , respectively . In a multivariable Cox proportional-hazards analysis , GLAS was an independent predictor of AF recurrence after catheter ablation in both the paroxysmal AF group ( hazard ratio : 0.79 , 95 % confidence interval : 0.67 - 0.96 ; P=0.01 ) and the persistent AF group ( hazard ratio : 0.81 , 95 % confidence interval : 0.71 - 0.93 ; P=0.004 ) . CONCLUSIONS In both paroxysmal and persistent AF , decreased baseline left atrial deformation capabilities assessed by two-dimensional STE can help to identify patients at high risk of AF recurrence after catheter ablation . This variable may help to guide c and i date selection and improve therapeutic strategies Background Atrial fibrillation ( AF ) is a common arrhythmia with relevant impact on mortality and morbidity .  Pulmonary vein isolation ( PVI ) is an established therapy in patients who remain symptomatic under optimal medical therapy . However , up to 70 % of patients present with recurrence of AF after PVI . Therefore , identifying ideal c and i date s is an unmet clinical need . Left atrial ( LA ) fibrosis is associated with reduced LA function . Analysis of LA mechanics using 2D speckle tracking echocardiography ( STE ) might give more insight into LA substrates and be therefore of predictive value . Methods This prospect i ve single-center pilot study included 31 patients ( mean age , 62.3 ± 9.1 years ; 19 males ) with AF who underwent PVI and 20 matched healthy controls ( mean age , 60.6 ± 6.6 years ; 10 males ) .  2D STE strain indices of LA reservoir ( RLA ) , conduit , and , if feasible , contractile function , were analyzed before and 6 months after PVI . Assessment of the LV diastolic function was based on st and ard indices . Responders to PVI were defined as being asymptomatic and free of AF in a 7-day Holter-ECG after 6 months . Results At baseline , all patients with AF had significantly lower reservoir and contractile function compared with controls . After 6 months , 17 patients ( 54.8 % ) were identified as responders . At baseline , the reservoir function was significantly higher in responders compared with nonresponders ( 32.7 ± 11.1 vs. 22.9 ± 10.9 % ; P = 0.019 ) . Only in responders , RLA and contractile LA function improved and reached normal values whereas LA function remained unchanged in nonresponders . In a ROC analysis , a RLA value of ≥19.5 % discriminated responders and nonresponders in patients with persistent AF with a sensitivity of 86 % and a specificity of 100 % ( P = 0.012 ; area under the curve 0.943 ; CI , 0.81–1.0 ) . Conclusions LA reservoir function helps to predict efficacy of PVI after 6 months . Only in responders , reservoir , and contractile function normalized within 6 months after PVI indicating a lower level of atrial remodeling at baseline . No deleterious effects of ablation were detected in nonresponders During the past three decades , catheter and surgical ablation of  atrial fibrillation ( AF ) have evolved from investigational procedures to their current role as effective treatment options for patients with AF .  Surgical ablation of AF , using either st and ard , minimally invasive , or hybrid techniques , is available in most major hospitals throughout the world . Catheter ablation of AF is even more widely available , and is now the most commonly performed catheter ablation procedure . In 2007 , an initial Consensus Statement on Catheter and Surgical AF Ablation was developed as a joint effort of the Heart Rhythm Society ( HRS ) , the European Heart Rhythm Association ( EHRA ) , and the European Cardiac Arrhythmia Society (ECAS).1 The 2007 document was also developed in collaboration with the Society of Thoracic Surgeons ( STS ) and the American College of Cardiology ( ACC ) . This Consensus Statement on Catheter and Surgical AF Ablation was rewritten in 2012 to reflect the many advances in AF ablation that had occurred in the interim.2 The rate of advancement in the tools , techniques , and outcomes of AF ablation continue to increase 
    Output:
    
agent
Lower values of PALS are associated with an increased risk of AF recurrence after RFA .
PALS provides prognostic value in clinical practice
***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 objective of this study was to investigate atrial myocardial properties through two-dimensional ( 2D ) myocardial imaging in patients with atrial fibrillation ( AF ) and its predictive role for recurrence after catheter ablation . Methods and results Echocardiographic examinations were performed in 40 patients with paroxysmal AF before catheter ablation and 40 age- and gender-matched healthy control subjects . Using a software package , bidimensional acquisitions were analyzed to measure longitudinal strain and strain rate for the left atrium ( LA ) . Systolic strain and strain rate in all eight segments , and its average values , were significantly reduced in AF patients compared to controls . During 9 months of follow-up after catheter ablation for AF , 11 of 40 AF patients had AF recurrence . AF recurrence was associated with gender , LA volume index , and average values of systolic strain and strain rate . By multivariate analysis , only average strain was an independent predictor of AF recurrence ( OR = 0.88 , 95 % CI 0.79 - 0.98 , p = 0.018 ) . Conclusions Lower systolic strain of LA was strongly associated with recurrence after catheter ablation . Thus , diverse adjunctive ablation strategies should be considered to reduce recurrence in patients with lower systolic strain AIMS The aim of this multicentre study was to determine the normal range and the clinical relevance of the myocardial function of the left atrium ( LA ) analysed by 2D speckle-tracking echocardiography ( 2DSTE ) . METHODS AND RESULTS We analysed 329 healthy adult subjects prospect ively included in 10 centres and a validation group of 377 patients with left ventricular diastolic dysfunction ( LVDD ) . LA myocardial function was analysed by LA strain rate peak during LA contraction ( LA-SRa ) and LA strain peak during LA relaxation ( LA-Strain ) . The range of values of LA myocardial function in healthy subjects was LA-SRa -2.11 ± 0.61 s(-1 ) and LA-Strain 45.5 ± 11.4 % , and the lowest expected values of these LA analyses ( calculated as -1.96 SD from the mean of healthy subjects ) were LA-SRa -0.91 s(-1 ) and LA-Strain 23.1 % . Concerning the clinical relevance of these LA myocardial analyses , LA-SRa and LA-Strain detected subtle LA dysfunction in patients with LVDD , even though LA volumetric measurements were normal . In addition , in these patients we found that the functional class ( dyspnoea-NYHA classification ) was inversely related to both LA-Strain and LA-SRa . CONCLUSION In the present multicentre study analysing a large cohort of healthy subjects and patients with LVDD , the normal range and the clinical relevance of the myocardial function of the LA using 2DSTE have been determined OBJECTIVE Since predictors of recurrence of atrial fibrillation ( AF ) after ablation procedures are poorly defined , this prospect i ve study was conducted to assess the value of left atrial ( LA ) deformation imaging with two-dimensional speckle-tracking ( 2D-ST ) to predict AF recurrences after successful ablation procedures . METHODS AND RESULTS One hundred and three consecutive patients ( age 58.1 ± 16.6 years , 72.8 % male ) with AF ( 76 paroxysmal , 27 persistent ) and 30 matched controls underwent transthoracic echocardiography and 2D-ST-LA-deformation analysis with assessment of LA-radial and LA-longitudinal strain ( Sr , Sl ) , and velocities derived from the apical 4- and 2-chamber views ( 4CV , 2CV ) . AF recurrence was assessed during 6 months of follow-up . For determination of AF-related LA changes , AF patients were compared to controls and patients with AF recurrences after ablation procedures ( n = 30 , 29.1 % ) were compared with patients who maintained sinus rhythm ( n = 73 , 70.9 % ) . Atrial deformation capabilities were significantly reduced ( P < 0.0005 ) in patients with AF ( 4CVSl 17.8 ± 13.5 % ; 4CVSr 22.3 ± 14.9 % ; 4CV-velocities 2.53 ± 0.97 seconds ) when compared with controls ( 4CVSl 31.3 ± 12.4 % ; 4CVSr 30.3 ± 9.1 % ; 4CV-velocities 3.48 ± 1.01 cm/s ) . Independent predictors for AF recurrence after ablation procedures were 2CV-LA-global-strain ( Sr , P = 0.03 ; Sl , P = 0.003 ) , 4CV-LA-gobal-strain ( Sr , P = 0.03 ; Sl , P = 0.02 ) , and regional LA-septal wall-Sl ( P = 0.008 ) . LA-global-strain parameters were superior to regional LA function analysis for the prediction of AF recurrences , with cutoff values ( cov ) , hazard ratios ( HR ) , positive and negative predictive values ( PPV , NPV ) were : 4CVSl cov , 10.79 % ( HR 27.8 , P < 0.0005 ; PPV 78.8 % , NPV 93.9 % ) , 4CVSr cov , -16.65 % ( HR 24.8 , P < 0.0005 ; PPV 69.4 % , NPV 96.6 % ) , 2CVSl cov , 12.31 % ( HR 22.7 , P < 0.0005 ; PPV 75.8 % , NPV 95.3 % ) , and 2CVSr cov , -14.9 % ( HR 12.9 , P < 0.0005 ; PPV 64.3 % , NPV 93.2 % ) . CONCLUSION Compared with controls , AF itself seems to decrease LA deformation capabilities . The assessment of global LA strain with 2D-ST identifies patients with high risk for AF recurrence after ablation procedures . This imaging technique may help to improve therapeutic guiding for patients with AF The incremental value of left atrial ( LA ) deformation analysis by speckle tracking echocardiography compared with LA volume or LA ejection fraction as a cardiovascular risk marker has not been evaluated prospect ively . We sought to compare LA function by speckle tracking echocardiography to other conventional LA parameters for prediction of adverse cardiovascular outcomes . This prospect i ve study included 312 adults ( mean age 71 ± 6 years , 56 % men ) in sinus rhythm who were followed for development of first atrial fibrillation , congestive heart failure , stroke , transient ischemic attack , myocardial infa rct ion , coronary revascularization , and cardiovascular death .  Global peak atrial longitudinal strain ( PALS ) by speckle tracking echocardiography was measured in all subjects by averaging all atrial segments . Left atrium was assessed with biplane LA volume , LA ejection fraction , 4-chamber LA area , and M-mode dimension . Of 312 subjects at baseline , 43 had 61 new events during a mean follow-up of 3.1 ± 1.4 years . All LA parameters , traditional parameters , and parameters derived by speckle tracking echocardiography were independently predictive of combined outcomes ( p < 0.0001 for all comparisons ) . Overall performance for prediction of cardiovascular events was greatest for global PALS ( area under receiver operator characteristic curve : global PALS 0.83 , indexed LA volume 0.71 , LA ejection fraction 0.69 , LA area 0.64 , LA diameter 0.59 ) . A grade d association between degree of LA enlargement and risk of cardiovascular events was evident only for global PALS and indexed LA volume . In conclusion , global PALS is a strong and independent predictor of cardiovascular events and appears to be superior to conventional parameters of LA analysis BACKGROUND Given the potential complications of atrial fibrillation ( AF ) recurrence after ablation , better predictors of the effectiveness of the procedure are necessary to guide patient selection . AIM This prospect i ve study was conducted to evaluate the clinical relevance of global left atrial longitudinal strain ( GLAS ) and AF recurrence after catheter ablation . METHODS In 115 consecutive patients with AF ( persistent , n=62 ; paroxysmal , n=53 ) ,  transthoracic echocardiography was performed before catheter ablation to assess baseline left atrial mechanical function using speckle tracking echocardiography ( STE ) . RESULTS After 12 months of follow-up , 22 ( 35.5 % ) patients in the persistent AF group and 15 ( 28.3 % ) in the paroxysmal AF group exhibited AF recurrence . In both the paroxysmal and persistent AF population s , patients with recurrence presented with significantly impaired GLAS compared with patients without recurrence . Patients with recurrence also had a significantly higher pro-B-type natriuretic peptide concentration . A receiver operator curve analysis yielded area under the curve values of 0.94 and 0.86 for paroxysmal and persistent AF , respectively . In a multivariable Cox proportional-hazards analysis , GLAS was an independent predictor of AF recurrence after catheter ablation in both the paroxysmal AF group ( hazard ratio : 0.79 , 95 % confidence interval : 0.67 - 0.96 ; P=0.01 ) and the persistent AF group ( hazard ratio : 0.81 , 95 % confidence interval : 0.71 - 0.93 ; P=0.004 ) . CONCLUSIONS In both paroxysmal and persistent AF , decreased baseline left atrial deformation capabilities assessed by two-dimensional STE can help to identify patients at high risk of AF recurrence after catheter ablation . This variable may help to guide c and i date selection and improve therapeutic strategies Background Atrial fibrillation ( AF ) is a common arrhythmia with relevant impact on mortality and morbidity .  Pulmonary vein isolation ( PVI ) is an established therapy in patients who remain symptomatic under optimal medical therapy . However , up to 70 % of patients present with recurrence of AF after PVI . Therefore , identifying ideal c and i date s is an unmet clinical need . Left atrial ( LA ) fibrosis is associated with reduced LA function . Analysis of LA mechanics using 2D speckle tracking echocardiography ( STE ) might give more insight into LA substrates and be therefore of predictive value . Methods This prospect i ve single-center pilot study included 31 patients ( mean age , 62.3 ± 9.1 years ; 19 males ) with AF who underwent PVI and 20 matched healthy controls ( mean age , 60.6 ± 6.6 years ; 10 males ) .  2D STE strain indices of LA reservoir ( RLA ) , conduit , and , if feasible , contractile function , were analyzed before and 6 months after PVI . Assessment of the LV diastolic function was based on st and ard indices . Responders to PVI were defined as being asymptomatic and free of AF in a 7-day Holter-ECG after 6 months . Results At baseline , all patients with AF had significantly lower reservoir and contractile function compared with controls . After 6 months , 17 patients ( 54.8 % ) were identified as responders . At baseline , the reservoir function was significantly higher in responders compared with nonresponders ( 32.7 ± 11.1 vs. 22.9 ± 10.9 % ; P = 0.019 ) . Only in responders , RLA and contractile LA function improved and reached normal values whereas LA function remained unchanged in nonresponders . In a ROC analysis , a RLA value of ≥19.5 % discriminated responders and nonresponders in patients with persistent AF with a sensitivity of 86 % and a specificity of 100 % ( P = 0.012 ; area under the curve 0.943 ; CI , 0.81–1.0 ) . Conclusions LA reservoir function helps to predict efficacy of PVI after 6 months . Only in responders , reservoir , and contractile function normalized within 6 months after PVI indicating a lower level of atrial remodeling at baseline . No deleterious effects of ablation were detected in nonresponders During the past three decades , catheter and surgical ablation of  atrial fibrillation ( AF ) have evolved from investigational procedures to their current role as effective treatment options for patients with AF .  Surgical ablation of AF , using either st and ard , minimally invasive , or hybrid techniques , is available in most major hospitals throughout the world . Catheter ablation of AF is even more widely available , and is now the most commonly performed catheter ablation procedure . In 2007 , an initial Consensus Statement on Catheter and Surgical AF Ablation was developed as a joint effort of the Heart Rhythm Society ( HRS ) , the European Heart Rhythm Association ( EHRA ) , and the European Cardiac Arrhythmia Society (ECAS).1 The 2007 document was also developed in collaboration with the Society of Thoracic Surgeons ( STS ) and the American College of Cardiology ( ACC ) . This Consensus Statement on Catheter and Surgical AF Ablation was rewritten in 2012 to reflect the many advances in AF ablation that had occurred in the interim.2 The rate of advancement in the tools , techniques , and outcomes of AF ablation continue to increase 
    Output:
    