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 —Pulmonary veins ( PVs ) play a pivotal role in initiating and perpetuating  atrial fibrillation ( AF ) . We investigated if PV electrical isolation from the left atrium is required for curing AF . Methods and Result —Fifty-one patients with paroxysmal or persistent AF underwent circumferential radiofrequency ablation of PV ostia performed with an anatomic approach . The end point of the ablation procedure was the recording of low peak-to-peak bipolar potentials ( < 0.1 mV ) inside the lesions . Left atrium pacing was used to assess the conduction between the PVs and the left atrium . During a mean follow-up period of 16.6±3.9 months , 41 patients ( 80.4 % ) were free of atrial arrhythmias . When patients with and without AF recurrence were analyzed , no significant difference was observed in the mean number of PVs in which the ablation end point was reached ( 3.4±1.2 versus 3.7±0.87 ) and PVs isolated ( 1.5±1.4 versus 1.6±1 ) . We noted that , although in 29 of 41 patients ( 71 % ) without AF recurrence , the ablation end point was reached in all PVs mapped , it was only possible to demonstrate the isolation of all PVs mapped in 2 patients . On the other h and , in 7 of 10 patients ( 70 % ) with AF recurrence , the ablation end point was reached in all PVs mapped , whereas one patient had all PVs isolated . Conclusions —Our findings show that with the use of a pure anatomic approach , it is possible to prevent AF in > 80 % of patients undergoing catheter ablation . Moreover , the isolation of PVs is not crucial for curing AF BACKGROUND Although radiofrequency ( RF ) ablation has long been the st and ard of care for atrial fibrillation ( AF ) ablation , cryoballoon technology has emerged as a feasible approach with promising results . Prospect i ve multicenter registry data referring to both ablation technologies in AF ablation are lacking so far . OBJECTIVE The purpose of this study was to report data from the German ablation registry with respect to efficacy and safety in pulmonary vein ablation with different energy sources for paroxysmal AF after 1-year follow-up . METHODS A total of 2306 patients with symptomatic paroxysmal AF from the German ablation registry were included in this analysis . The cohort was divided into two groups according to the ablation energy source used : cryoballoon and RF ablation .  MACCE was defined as a combination of death , myocardial infa rct ion , or stroke . RESULTS AF recurrence rate after a single ablation procedure at 1 year follow-up was not significantly different between the two groups ( 45.8 % after cryoablation and 45.4 % after RF ablation , P = .87 ) . Also , the rate of patients without AF recurrence and free of antiarrhythmic drug at 12-month follow-up was similar ( cryoablation 44.2 % and RF 41.4 % , P = .25 ) . MACCE occurred with an incidence of 0.7 % within 500 days after cryoablation and 1.4 % after RF ablation ( P = .30 ) . Persistent phrenic nerve palsy was more common after cryoablation compared to RF ablation ( 1.1 % vs. 0.3 % , P < .05 ) . CONCLUSION AF recurrence rate at 1-year follow-up was similar in RF ablation compared to cryoablation , whereas the spectrum and relevance of complications were significantly different between the two ablation methods . This finding might influence the choice of ablation method offered to the individual paroxysmal AF patient Background Radiofrequency and cryoballoon pulmonary vein isolation are common approaches for paroxysmal atrial fibrillation treatment , showing similar results in recent multicenter studies , including heterogeneous tools and protocol s. The aim of this study is to compare prospect ively in a single , high-volume center the outcome of paroxysmal atrial fibrillation ablation performed specifically by second-generation cryoballoon or contact force radiofrequency ablation . Methods Consecutive patients scheduled for paroxysmal atrial fibrillation transcatheter ablation have been included and prospect ively followed up . Aim ing to reduce potential bias deriving from baseline characteristics , a propensity score matching analysis has been performed to analyze safety and efficacy outcomes . Results Out of consecutive patients undergoing atrial fibrillation transcatheter ablation between January 2015 and December 2016 , 46 patients approached by cryoablation  were matched 1 : 1 by propensity score to a similar population treated by last-generation radiofrequency ablation .  Freedom from atrial fibrillation after 12 months ( 76 vs. 78 % , P = 0.804 ) and incidence of complications ( 4 vs. 6 % , P = 0.168 ) did not differ between the two groups . Radiological exposure was higher for the cryoballoon group ( 11 vs. 4 min , P < 0.001 ) , whereas procedural duration did not differ ( P = 0.174 ) . Aim ing to assess the potential impact of a learning curve in patients undergoing cryoablation , the first-third of patients ( n = 15 ) were compared with the remaining , reporting longer radiological exposure ( P < 0.001 ) , but similar safety and efficacy . Conclusion In this propensity score analysis , last-generation cryoballoon and radiofrequency catheters for atrial fibrillation ablation present similar efficacy and safety .  Cryoablation requires longer fluoroscopy exposure compared with radiofrequency , although this is reduced by increased experience INTRODUCTION There are limited comparative data on catheter ablation of atrial fibrillation ( CAAF ) using the second-generation cryoballoon ( CB-2 ) versus point-by-point radiofrequency ( RF ) . This study examines the acute/long-term CAAF outcomes using these 2 strategies . METHODS AND RESULTS In this multicenter , retrospective , nonr and omized analysis , procedural and clinical outcomes of 1,196 patients ( 76 % with paroxysmal AF ) undergoing CAAF using CB-2 ( n = 773 ) and open-irrigated , non-force sensing RF ( n = 423 ) were evaluated . Pulmonary vein isolation was achieved in 98 % with CB-2 and 99 % with RF ( P = 0.168 ) . CB-2 was associated with shorter ablation time ( 40 ± 14 min vs. 66 ± 26 min ; P < 0.001 ) and procedure time ( 145 ± 49 minutes vs. 188 ± 42 minutes ; P < 0.001 ) , but greater fluoroscopic utilization ( 29 ± 13 minutes vs. 23 ± 14 minutes ; P < 0.001 ) . While transient ( 7.6 % vs. 0 % ; P < 0.001 ) and persistent ( 1.2 % vs. 0 % ; P = 0.026 ) phrenic nerve palsy occurred exclusively with CB-2 , other adverse event rates were similar between CB-2 ( 1.6 % ) and RF ( 2.6 % ) ; P = 0.207 . However , freedom from AF/atrial flutter/tachycardia at 12 months following a single procedure without antiarrhythmic therapy was greater with CB-2 ( 76.6 % ) versus RF ( 60.4 % ) ; P < 0.001 . While this difference was evident in patients with paroxysmal AF ( P < 0.001 ) , it did not reach significance in those with persistent AF ( P = 0.089 ) . Additionally , CB-2 was associated with reduced long-term need for antiarrhythmic therapy ( 16.7 % vs. 22.0 % ; P = 0.024 ) and repeat ablations ( 14.6 % vs. 24.1 % ; P < 0.001 ) . CONCLUSION In this multicenter , retrospective , nonr and omized study , CAAF using CB-2 coupled with RF as occasionally required was associated with greater freedom from atrial arrhythmias at 12 months following a single procedure without antiarrhythmic therapy when compared to open-irrigated , non-force sensing RF , alone AIMS The second-generation cryoballoon ( CB2 ) with increased surface cooling has recently become available . The aim was to investigate the incidence and characteristics of phrenic nerve palsy ( PNP ) during pulmonary vein isolation ( PVI ) using the CB2 as compared with the first-generation balloon ( CB1 ) . METHODS AND RESULTS A total of 360 consecutive patients with atrial fibrillation underwent PVI with the CB1 ( 106 patients ) or the CB2 ( 254 patients ) .  Right PN function was monitored by continuous stimulation and palpation during septal PV ablation . Persistent PNP ( present at discharge ) occurred in 2.8 and 1.9 % ( P = 0.63 ) of patients , transient PNP ( full recovery before discharge ) in 5.9 and 3.8 % ( P = 0.41 ) of patients in the CB2 and CB1 group , respectively . Phrenic nerve palsy during ablation at the right inferior PV was observed in 0 % ( CB1 ) and 4.3 % ( CB2 , P = 0.03 ) of patients . Using the CB2 , a trend of reduced incidence of persistent PNP over quartiles of consecutive patients was observed [ 4.8 % ( Q1 ) vs. 0 % ( Q4 ) ; P = 0.077 ] . At the culprit PV , PNP occurred after 3.5 ± 2.1 ( CB1 ) and 1.1 ± 0.4 applications ( CB2 ; P = 0.036 ) . Complete recovery of PN function occurred after 29 ± 11 ( CB1 ) and 259 ± 137 days ( CB2 ; P = 0.004 ) . CONCLUSIONS The rate of transient/persistent PNP associated with the use of the CB2 was 5.9 and 2.8 % , respectively . Time to restitution of PN function was longer using the CB2 BACKGROUND Catheter ablation is an established treatment for atrial fibrillation ( AF ) .  Cryoballoon ablation ( CBA ) has emerged as an alternative to radiofrequency ablation ( RFA ) . However , there are few data comparing these modalities for treatment of paroxysmal AF ( pAF ) in the U.S. POPULATION The purpose of this study was to compare procedural times , safety , and efficacy of CBA against RFA . METHODS A single-center prospect i ve cohort study evaluated patients who underwent catheter ablation for pAF using CBA or RFA between January 1 , 2010 and October 31 , 2013 . Patients with prior ablation and those without rhythm follow-up for at least 3 months were excluded . The primary end point was freedom from AF , atrial flutter , and atrial tachycardia ( FFAF ) > 30 seconds after a 3-month blanking period without requirement for antiarrhythmic drugs . We also compared rates of successful pulmonary vein isolation ( PVI ) , fluoroscopy and procedure times , and major complication rates . RESULTS A total of 201 patients were included ( CBA = 101 , RFA = 100 ) . The rate of successful PVI was 99.3 % in CBA versus 97.4 % in RFA ( P = 0.08 ) . Procedure times were shorter with CBA ( 192.9 ± 44.0 minutes vs 283.7 ± 78.0 minutes , P < 0.001 ) as well as total fluoroscopy times ( 46.0 ± 22.4 minutes vs 73.0 ± 30.1 minutes , P < 0.001 ) . Overall complication rates were equivalent ; however , fewer cardiac perforations occurred with CBA ( 0 % vs 4 % , P = 0.042 ) . The 1-year FFAF rates were 60.3 % for CBA and 61.1 % for RFA ( log rank P = 0.93 ) . CONCLUSION CBA was associated with equivalent 1-year FFAF rate as RFA for pAF . Procedure and fluoroscopy times were shorter for CBA and fewer cardiac perforations occurred Purpose Recent data show no benefit of additional ablation beyond pulmonary vein isolation ( PVI ) in persistent atrial fibrillation ( AF ) . Evidence suggests that radiofrequency energy ( RF ) and cryoballoon ( CRYO ) have comparable efficacy for PVI . We aim ed to assess the outcomes after a single catheter ablation procedure , comparing PVI using CRYO vs. RF ablation for PVI plus additional ablation in a cohort of patients with persistent AF . Methods In this prospect i ve multicenter propensity score-matched comparison , 59 consecutive patients undergoing CRYO ablation of persistent AF were matched to 59 patients treated with RF from November 2010 to June 2012 . Results During a mean follow-up of 15.6 ± 11.5 months , 43.2 % of patients presented atrial arrhythmia relapse after a blanking period of 3 months , which was comparable between the two groups ( 40.7 % in CRYO vs. 45.8 % in RF , Log rank P = 0.14 ; HR = 0.67 , 95 % CI 0.38–1.1 
    Output:
    
agent
Conclusion In patients with paroxysmal atrial fibrillation  , cryoballoon and radiofrequency ablation produce similar results in terms of freedom from recurrent atrial fibrillation or atrial tachyarrhythmias but with a different safety profile , being cryoballoon ablation less associated with cardiac complications but more likely to cause phrenic nerve palsy
***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 —Pulmonary veins ( PVs ) play a pivotal role in initiating and perpetuating  atrial fibrillation ( AF ) . We investigated if PV electrical isolation from the left atrium is required for curing AF . Methods and Result —Fifty-one patients with paroxysmal or persistent AF underwent circumferential radiofrequency ablation of PV ostia performed with an anatomic approach . The end point of the ablation procedure was the recording of low peak-to-peak bipolar potentials ( < 0.1 mV ) inside the lesions . Left atrium pacing was used to assess the conduction between the PVs and the left atrium . During a mean follow-up period of 16.6±3.9 months , 41 patients ( 80.4 % ) were free of atrial arrhythmias . When patients with and without AF recurrence were analyzed , no significant difference was observed in the mean number of PVs in which the ablation end point was reached ( 3.4±1.2 versus 3.7±0.87 ) and PVs isolated ( 1.5±1.4 versus 1.6±1 ) . We noted that , although in 29 of 41 patients ( 71 % ) without AF recurrence , the ablation end point was reached in all PVs mapped , it was only possible to demonstrate the isolation of all PVs mapped in 2 patients . On the other h and , in 7 of 10 patients ( 70 % ) with AF recurrence , the ablation end point was reached in all PVs mapped , whereas one patient had all PVs isolated . Conclusions —Our findings show that with the use of a pure anatomic approach , it is possible to prevent AF in > 80 % of patients undergoing catheter ablation . Moreover , the isolation of PVs is not crucial for curing AF BACKGROUND Although radiofrequency ( RF ) ablation has long been the st and ard of care for atrial fibrillation ( AF ) ablation , cryoballoon technology has emerged as a feasible approach with promising results . Prospect i ve multicenter registry data referring to both ablation technologies in AF ablation are lacking so far . OBJECTIVE The purpose of this study was to report data from the German ablation registry with respect to efficacy and safety in pulmonary vein ablation with different energy sources for paroxysmal AF after 1-year follow-up . METHODS A total of 2306 patients with symptomatic paroxysmal AF from the German ablation registry were included in this analysis . The cohort was divided into two groups according to the ablation energy source used : cryoballoon and RF ablation .  MACCE was defined as a combination of death , myocardial infa rct ion , or stroke . RESULTS AF recurrence rate after a single ablation procedure at 1 year follow-up was not significantly different between the two groups ( 45.8 % after cryoablation and 45.4 % after RF ablation , P = .87 ) . Also , the rate of patients without AF recurrence and free of antiarrhythmic drug at 12-month follow-up was similar ( cryoablation 44.2 % and RF 41.4 % , P = .25 ) . MACCE occurred with an incidence of 0.7 % within 500 days after cryoablation and 1.4 % after RF ablation ( P = .30 ) . Persistent phrenic nerve palsy was more common after cryoablation compared to RF ablation ( 1.1 % vs. 0.3 % , P < .05 ) . CONCLUSION AF recurrence rate at 1-year follow-up was similar in RF ablation compared to cryoablation , whereas the spectrum and relevance of complications were significantly different between the two ablation methods . This finding might influence the choice of ablation method offered to the individual paroxysmal AF patient Background Radiofrequency and cryoballoon pulmonary vein isolation are common approaches for paroxysmal atrial fibrillation treatment , showing similar results in recent multicenter studies , including heterogeneous tools and protocol s. The aim of this study is to compare prospect ively in a single , high-volume center the outcome of paroxysmal atrial fibrillation ablation performed specifically by second-generation cryoballoon or contact force radiofrequency ablation . Methods Consecutive patients scheduled for paroxysmal atrial fibrillation transcatheter ablation have been included and prospect ively followed up . Aim ing to reduce potential bias deriving from baseline characteristics , a propensity score matching analysis has been performed to analyze safety and efficacy outcomes . Results Out of consecutive patients undergoing atrial fibrillation transcatheter ablation between January 2015 and December 2016 , 46 patients approached by cryoablation  were matched 1 : 1 by propensity score to a similar population treated by last-generation radiofrequency ablation .  Freedom from atrial fibrillation after 12 months ( 76 vs. 78 % , P = 0.804 ) and incidence of complications ( 4 vs. 6 % , P = 0.168 ) did not differ between the two groups . Radiological exposure was higher for the cryoballoon group ( 11 vs. 4 min , P < 0.001 ) , whereas procedural duration did not differ ( P = 0.174 ) . Aim ing to assess the potential impact of a learning curve in patients undergoing cryoablation , the first-third of patients ( n = 15 ) were compared with the remaining , reporting longer radiological exposure ( P < 0.001 ) , but similar safety and efficacy . Conclusion In this propensity score analysis , last-generation cryoballoon and radiofrequency catheters for atrial fibrillation ablation present similar efficacy and safety .  Cryoablation requires longer fluoroscopy exposure compared with radiofrequency , although this is reduced by increased experience INTRODUCTION There are limited comparative data on catheter ablation of atrial fibrillation ( CAAF ) using the second-generation cryoballoon ( CB-2 ) versus point-by-point radiofrequency ( RF ) . This study examines the acute/long-term CAAF outcomes using these 2 strategies . METHODS AND RESULTS In this multicenter , retrospective , nonr and omized analysis , procedural and clinical outcomes of 1,196 patients ( 76 % with paroxysmal AF ) undergoing CAAF using CB-2 ( n = 773 ) and open-irrigated , non-force sensing RF ( n = 423 ) were evaluated . Pulmonary vein isolation was achieved in 98 % with CB-2 and 99 % with RF ( P = 0.168 ) . CB-2 was associated with shorter ablation time ( 40 ± 14 min vs. 66 ± 26 min ; P < 0.001 ) and procedure time ( 145 ± 49 minutes vs. 188 ± 42 minutes ; P < 0.001 ) , but greater fluoroscopic utilization ( 29 ± 13 minutes vs. 23 ± 14 minutes ; P < 0.001 ) . While transient ( 7.6 % vs. 0 % ; P < 0.001 ) and persistent ( 1.2 % vs. 0 % ; P = 0.026 ) phrenic nerve palsy occurred exclusively with CB-2 , other adverse event rates were similar between CB-2 ( 1.6 % ) and RF ( 2.6 % ) ; P = 0.207 . However , freedom from AF/atrial flutter/tachycardia at 12 months following a single procedure without antiarrhythmic therapy was greater with CB-2 ( 76.6 % ) versus RF ( 60.4 % ) ; P < 0.001 . While this difference was evident in patients with paroxysmal AF ( P < 0.001 ) , it did not reach significance in those with persistent AF ( P = 0.089 ) . Additionally , CB-2 was associated with reduced long-term need for antiarrhythmic therapy ( 16.7 % vs. 22.0 % ; P = 0.024 ) and repeat ablations ( 14.6 % vs. 24.1 % ; P < 0.001 ) . CONCLUSION In this multicenter , retrospective , nonr and omized study , CAAF using CB-2 coupled with RF as occasionally required was associated with greater freedom from atrial arrhythmias at 12 months following a single procedure without antiarrhythmic therapy when compared to open-irrigated , non-force sensing RF , alone AIMS The second-generation cryoballoon ( CB2 ) with increased surface cooling has recently become available . The aim was to investigate the incidence and characteristics of phrenic nerve palsy ( PNP ) during pulmonary vein isolation ( PVI ) using the CB2 as compared with the first-generation balloon ( CB1 ) . METHODS AND RESULTS A total of 360 consecutive patients with atrial fibrillation underwent PVI with the CB1 ( 106 patients ) or the CB2 ( 254 patients ) .  Right PN function was monitored by continuous stimulation and palpation during septal PV ablation . Persistent PNP ( present at discharge ) occurred in 2.8 and 1.9 % ( P = 0.63 ) of patients , transient PNP ( full recovery before discharge ) in 5.9 and 3.8 % ( P = 0.41 ) of patients in the CB2 and CB1 group , respectively . Phrenic nerve palsy during ablation at the right inferior PV was observed in 0 % ( CB1 ) and 4.3 % ( CB2 , P = 0.03 ) of patients . Using the CB2 , a trend of reduced incidence of persistent PNP over quartiles of consecutive patients was observed [ 4.8 % ( Q1 ) vs. 0 % ( Q4 ) ; P = 0.077 ] . At the culprit PV , PNP occurred after 3.5 ± 2.1 ( CB1 ) and 1.1 ± 0.4 applications ( CB2 ; P = 0.036 ) . Complete recovery of PN function occurred after 29 ± 11 ( CB1 ) and 259 ± 137 days ( CB2 ; P = 0.004 ) . CONCLUSIONS The rate of transient/persistent PNP associated with the use of the CB2 was 5.9 and 2.8 % , respectively . Time to restitution of PN function was longer using the CB2 BACKGROUND Catheter ablation is an established treatment for atrial fibrillation ( AF ) .  Cryoballoon ablation ( CBA ) has emerged as an alternative to radiofrequency ablation ( RFA ) . However , there are few data comparing these modalities for treatment of paroxysmal AF ( pAF ) in the U.S. POPULATION The purpose of this study was to compare procedural times , safety , and efficacy of CBA against RFA . METHODS A single-center prospect i ve cohort study evaluated patients who underwent catheter ablation for pAF using CBA or RFA between January 1 , 2010 and October 31 , 2013 . Patients with prior ablation and those without rhythm follow-up for at least 3 months were excluded . The primary end point was freedom from AF , atrial flutter , and atrial tachycardia ( FFAF ) > 30 seconds after a 3-month blanking period without requirement for antiarrhythmic drugs . We also compared rates of successful pulmonary vein isolation ( PVI ) , fluoroscopy and procedure times , and major complication rates . RESULTS A total of 201 patients were included ( CBA = 101 , RFA = 100 ) . The rate of successful PVI was 99.3 % in CBA versus 97.4 % in RFA ( P = 0.08 ) . Procedure times were shorter with CBA ( 192.9 ± 44.0 minutes vs 283.7 ± 78.0 minutes , P < 0.001 ) as well as total fluoroscopy times ( 46.0 ± 22.4 minutes vs 73.0 ± 30.1 minutes , P < 0.001 ) . Overall complication rates were equivalent ; however , fewer cardiac perforations occurred with CBA ( 0 % vs 4 % , P = 0.042 ) . The 1-year FFAF rates were 60.3 % for CBA and 61.1 % for RFA ( log rank P = 0.93 ) . CONCLUSION CBA was associated with equivalent 1-year FFAF rate as RFA for pAF . Procedure and fluoroscopy times were shorter for CBA and fewer cardiac perforations occurred Purpose Recent data show no benefit of additional ablation beyond pulmonary vein isolation ( PVI ) in persistent atrial fibrillation ( AF ) . Evidence suggests that radiofrequency energy ( RF ) and cryoballoon ( CRYO ) have comparable efficacy for PVI . We aim ed to assess the outcomes after a single catheter ablation procedure , comparing PVI using CRYO vs. RF ablation for PVI plus additional ablation in a cohort of patients with persistent AF . Methods In this prospect i ve multicenter propensity score-matched comparison , 59 consecutive patients undergoing CRYO ablation of persistent AF were matched to 59 patients treated with RF from November 2010 to June 2012 . Results During a mean follow-up of 15.6 ± 11.5 months , 43.2 % of patients presented atrial arrhythmia relapse after a blanking period of 3 months , which was comparable between the two groups ( 40.7 % in CRYO vs. 45.8 % in RF , Log rank P = 0.14 ; HR = 0.67 , 95 % CI 0.38–1.1 
    Output:
    