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: OBJECTIVES This study sought to assess the safety and effectiveness of a novel cryoballoon ablation technology design ed to achieve single-delivery pulmonary vein ( PV ) isolation . BACKGROUND St and ard radiofrequency ablation is effective in eliminating atrial fibrillation ( AF ) but requires multiple lesion delivery at the risk of significant complications . METHODS Patients with documented symptomatic paroxysmal AF and previously failed therapy with ≥ 1 membrane active antiarrhythmic drug underwent 2:1 r and omization to either cryoballoon ablation ( n = 163 ) or drug therapy ( n = 82 ) . A 90-day blanking period allowed for optimization of antiarrhythmic drug therapy and reablation if necessary . Effectiveness of the cryoablation procedure versus drug therapy was determined at 12 months . RESULTS Patients had highly symptomatic AF ( 78 % paroxysmal , 22 % early persistent ) and experienced failure of at least one antiarrhythmic drug . Cryoablation produced acute isolation of three or more PVs in 98.2 % and all four PVs in 97.6 % of patients . PVs isolation was achieved with the balloon catheter alone in 83 % . At 12 months , treatment success was 69.9 % ( 114 of 163 ) of cryoblation patients compared with 7.3 % of antiarrhythmic drug patients ( absolute difference , 62.6 % [ p < 0.001 ] ) . Sixty-five ( 79 % ) drug-treated patients crossed over to cryoablation during 12 months of study follow-up due to recurrent , symptomatic AF , constituting drug treatment failure . There were 7 of the result ing 228 cryoablated patients ( 3.1 % ) with a > 75 % reduction in PV area during 12 months of follow-up . Twenty-nine of 259 procedures ( 11.2 % ) were associated with phrenic nerve palsy as determined by radiographic screening ; 25 of these had resolved by 12 months . Cryoablation patients had significantly improved symptoms at 12 months . CONCLUSIONS The STOP AF trial demonstrated that cryoballoon ablation is a safe and effective alternative to antiarrhythmic medication for the treatment of patients with symptomatic paroxysmal AF , for whom at least one antiarrhythmic drug has failed , with risks within accepted st and ards for ablation therapy . ( A Clinical Study of the A rct ic Front Cryoablation Balloon for the Treatment of Paroxysmal Atrial Fibrillation [ Stop AF ] ; NCT00523978 ) 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 OBJECTIVES The purpose of this study was to investigate long-term outcomes of freedom from atrial fibrillation ( AF ) after pulmonary vein ( PV ) isolation using cryoballoon ablation with balloon-size selection based on individual PV diameters . BACKGROUND Data are lacking on long-term outcomes from cryoablation and on the most effective balloon size . METHODS This was a prospect i ve observational study involving 605 consecutively enrolled patients with symptomatic paroxysmal AF ( n = 579 ) or persistent AF .  Cryoballoon size was based on magnetic resonance imaging and /or conventional angiograms . Patients were followed up every 3 months during the first year after discharge and every 6 months in the second year . After 24 months , follow-up was on an outpatient basis with documented AF episodes recorded . RESULTS The PV isolation was achieved without touch-up in 91.1 % of patients , using the smaller balloon in 26.7 % , the larger balloon in 25.6 % , and both balloons in 47.7 % of patients . Follow-up data for > 12 months ( median 30 months ; interquartile range 18 to 48 months ) were available for 451 patients , 278 ( 61.6 % ) of whom were free of AF recurrence with no need for repeat procedures after the 3-month blanking period . Rates of freedom from AF after 1 , 2 , and 3 repeat procedures ( using cryoballoon or radiofrequency ablation with similar success rates ) were 74.9 % , 76.2 % , and 76.9 % , respectively . Use of the smaller balloons or both balloons produced the highest rates of long-term freedom from AF . Phrenic nerve palsy occurred in 12 patients ( 2 % ) , resolving within 3 to 9 months . CONCLUSIONS Rates of long-term freedom from AF after cryoballoon ablation are similar to those reported for radiofrequency ablation . A choice between balloons may improve outcomes BACKGROUND Contact force ( CF ) monitoring could be useful in accomplishing circumferential pulmonary vein ( PV ) isolation ( CPVI ) for atrial fibrillation ( AF ) . OBJECTIVE The purpose of this study was to compare procedure parameters and outcomes between CF-guided and non-guided CPVI . METHODS Thirty-eight consecutive AF patients ( mean age 60 ± 11 years , 28 paroxysmal AF ) undergoing CPVI were r and omized to non-CF-guided ( n = 19 ) and CF-guided ( n = 19 ) groups .  CPVI was performed with the ThermoCool SmartTouch catheter in both groups . The end-point was bidirectional block between the left atrium ( LA ) and PV . In the CF group , CF was kept between 10 and 20 g during CPVI , whereas in the non-CF group , all CF information was blanked . Radiofrequency energy at 30 W in the anterior and 25 W in the posterior LA wall was applied for 20 - 25 seconds at each point . RESULTS CPVI was successfully accomplished without any major complications in both groups . Mean CF in the non-CF and CF groups were 5.9 ± 4.5 g and 11.1 ± 4.3 g , respectively , for left-side CPVI , and 9.8 ± 6.6 g and 12.1 ± 4.8 g , respectively , for right-side CPVI ( both P < .001 ) . The procedure and fluoroscopy times  for CPVI in the non-CF and CF groups were 96 ± 39 minutes and 59 ± 16 minutes , respectively ( P < .001 ) , and 22 ± 63 seconds and 9 ± 20 seconds ( P = NS ) , respectively . Total number of residual conduction gaps was 6.3 ± 3.0 in the non-CF group and 2.8 ± 1.9 in the CF group ( P < .001 ) . During 6-month follow-up , 84.2 % of patients in the non-CF group and 94.7 % in the CF group were free from any atrial tachyarrhythmias ( P = .34 ) . CONCLUSION CF-guided CPVI  is effective in reducing procedure time and additional touch-up ablation and may improve long-term outcome Background — There is a lack of data on the comparative efficacy and procedural safety of open irrigated radiofrequency ( RF ) and cryoballoon catheter ( CB ) ablation for pulmonary vein isolation in patients with paroxysmal atrial fibrillation . Methods and Results — In a prospect i ve , noninferiority study , 315 patients were r and omly assigned to RF ( n=159 ) or CB ( n=156 ) ablation . The primary end point was freedom from atrial arrhythmia with absence of persistent complications . Patients were largely comparable between groups with more vascular disease in the RF group ( 8.2 % versus 2.6 % for CB ; P=0.028 ) . The primary end point at 12 months was achieved by 70.7 % with RF and 73.6 % with CB ( multiple procedure success ) , including 31 redo procedures in each group ( 19.5 % of RF versus 19.9 % of CB ; P=0.933 ) . For the intention-to-treat population , noninferiority of CB was revealed for the predefined inferiority margin ( risk difference , 0.029 ; 95 % confidence interval , −0.074 to 0.132 ; P<0.001 ) . Rates at 6 months were 63.1 % and 64.1 % for the RF and CB groups ( single procedure success ) , and noninferiority was confirmed ( risk difference , 0.010 ; 95 % confidence interval , −0.097 to 0.116 ; P=0.002 ) . Periprocedural complications for the index procedure were more frequent in the CB group ( 5.0 % RF , 12.2 % CB ; P=0.022 ) with a significant difference in phrenic nerve palsies ( 0 % RF , 5.8 % CB ; P=0.002 ) . Conclusion — This large , prospect i ve , r and omized , controlled study demonstrates noninferiority of CB ablation versus RF ablation for treating patients with paroxysmal atrial fibrillation . Clinical Trial Registration — URL : http://www . clinical trials.gov . Unique identifier : NCT00774566 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 card 
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agent
Conclusions CB-2 tended to be more effective in comparison to NCF catheter and at least non-inferior to CF catheter , with shorter procedure time and similar safety endpoint
***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: OBJECTIVES This study sought to assess the safety and effectiveness of a novel cryoballoon ablation technology design ed to achieve single-delivery pulmonary vein ( PV ) isolation . BACKGROUND St and ard radiofrequency ablation is effective in eliminating atrial fibrillation ( AF ) but requires multiple lesion delivery at the risk of significant complications . METHODS Patients with documented symptomatic paroxysmal AF and previously failed therapy with ≥ 1 membrane active antiarrhythmic drug underwent 2:1 r and omization to either cryoballoon ablation ( n = 163 ) or drug therapy ( n = 82 ) . A 90-day blanking period allowed for optimization of antiarrhythmic drug therapy and reablation if necessary . Effectiveness of the cryoablation procedure versus drug therapy was determined at 12 months . RESULTS Patients had highly symptomatic AF ( 78 % paroxysmal , 22 % early persistent ) and experienced failure of at least one antiarrhythmic drug . Cryoablation produced acute isolation of three or more PVs in 98.2 % and all four PVs in 97.6 % of patients . PVs isolation was achieved with the balloon catheter alone in 83 % . At 12 months , treatment success was 69.9 % ( 114 of 163 ) of cryoblation patients compared with 7.3 % of antiarrhythmic drug patients ( absolute difference , 62.6 % [ p < 0.001 ] ) . Sixty-five ( 79 % ) drug-treated patients crossed over to cryoablation during 12 months of study follow-up due to recurrent , symptomatic AF , constituting drug treatment failure . There were 7 of the result ing 228 cryoablated patients ( 3.1 % ) with a > 75 % reduction in PV area during 12 months of follow-up . Twenty-nine of 259 procedures ( 11.2 % ) were associated with phrenic nerve palsy as determined by radiographic screening ; 25 of these had resolved by 12 months . Cryoablation patients had significantly improved symptoms at 12 months . CONCLUSIONS The STOP AF trial demonstrated that cryoballoon ablation is a safe and effective alternative to antiarrhythmic medication for the treatment of patients with symptomatic paroxysmal AF , for whom at least one antiarrhythmic drug has failed , with risks within accepted st and ards for ablation therapy . ( A Clinical Study of the A rct ic Front Cryoablation Balloon for the Treatment of Paroxysmal Atrial Fibrillation [ Stop AF ] ; NCT00523978 ) 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 OBJECTIVES The purpose of this study was to investigate long-term outcomes of freedom from atrial fibrillation ( AF ) after pulmonary vein ( PV ) isolation using cryoballoon ablation with balloon-size selection based on individual PV diameters . BACKGROUND Data are lacking on long-term outcomes from cryoablation and on the most effective balloon size . METHODS This was a prospect i ve observational study involving 605 consecutively enrolled patients with symptomatic paroxysmal AF ( n = 579 ) or persistent AF .  Cryoballoon size was based on magnetic resonance imaging and /or conventional angiograms . Patients were followed up every 3 months during the first year after discharge and every 6 months in the second year . After 24 months , follow-up was on an outpatient basis with documented AF episodes recorded . RESULTS The PV isolation was achieved without touch-up in 91.1 % of patients , using the smaller balloon in 26.7 % , the larger balloon in 25.6 % , and both balloons in 47.7 % of patients . Follow-up data for > 12 months ( median 30 months ; interquartile range 18 to 48 months ) were available for 451 patients , 278 ( 61.6 % ) of whom were free of AF recurrence with no need for repeat procedures after the 3-month blanking period . Rates of freedom from AF after 1 , 2 , and 3 repeat procedures ( using cryoballoon or radiofrequency ablation with similar success rates ) were 74.9 % , 76.2 % , and 76.9 % , respectively . Use of the smaller balloons or both balloons produced the highest rates of long-term freedom from AF . Phrenic nerve palsy occurred in 12 patients ( 2 % ) , resolving within 3 to 9 months . CONCLUSIONS Rates of long-term freedom from AF after cryoballoon ablation are similar to those reported for radiofrequency ablation . A choice between balloons may improve outcomes BACKGROUND Contact force ( CF ) monitoring could be useful in accomplishing circumferential pulmonary vein ( PV ) isolation ( CPVI ) for atrial fibrillation ( AF ) . OBJECTIVE The purpose of this study was to compare procedure parameters and outcomes between CF-guided and non-guided CPVI . METHODS Thirty-eight consecutive AF patients ( mean age 60 ± 11 years , 28 paroxysmal AF ) undergoing CPVI were r and omized to non-CF-guided ( n = 19 ) and CF-guided ( n = 19 ) groups .  CPVI was performed with the ThermoCool SmartTouch catheter in both groups . The end-point was bidirectional block between the left atrium ( LA ) and PV . In the CF group , CF was kept between 10 and 20 g during CPVI , whereas in the non-CF group , all CF information was blanked . Radiofrequency energy at 30 W in the anterior and 25 W in the posterior LA wall was applied for 20 - 25 seconds at each point . RESULTS CPVI was successfully accomplished without any major complications in both groups . Mean CF in the non-CF and CF groups were 5.9 ± 4.5 g and 11.1 ± 4.3 g , respectively , for left-side CPVI , and 9.8 ± 6.6 g and 12.1 ± 4.8 g , respectively , for right-side CPVI ( both P < .001 ) . The procedure and fluoroscopy times  for CPVI in the non-CF and CF groups were 96 ± 39 minutes and 59 ± 16 minutes , respectively ( P < .001 ) , and 22 ± 63 seconds and 9 ± 20 seconds ( P = NS ) , respectively . Total number of residual conduction gaps was 6.3 ± 3.0 in the non-CF group and 2.8 ± 1.9 in the CF group ( P < .001 ) . During 6-month follow-up , 84.2 % of patients in the non-CF group and 94.7 % in the CF group were free from any atrial tachyarrhythmias ( P = .34 ) . CONCLUSION CF-guided CPVI  is effective in reducing procedure time and additional touch-up ablation and may improve long-term outcome Background — There is a lack of data on the comparative efficacy and procedural safety of open irrigated radiofrequency ( RF ) and cryoballoon catheter ( CB ) ablation for pulmonary vein isolation in patients with paroxysmal atrial fibrillation . Methods and Results — In a prospect i ve , noninferiority study , 315 patients were r and omly assigned to RF ( n=159 ) or CB ( n=156 ) ablation . The primary end point was freedom from atrial arrhythmia with absence of persistent complications . Patients were largely comparable between groups with more vascular disease in the RF group ( 8.2 % versus 2.6 % for CB ; P=0.028 ) . The primary end point at 12 months was achieved by 70.7 % with RF and 73.6 % with CB ( multiple procedure success ) , including 31 redo procedures in each group ( 19.5 % of RF versus 19.9 % of CB ; P=0.933 ) . For the intention-to-treat population , noninferiority of CB was revealed for the predefined inferiority margin ( risk difference , 0.029 ; 95 % confidence interval , −0.074 to 0.132 ; P<0.001 ) . Rates at 6 months were 63.1 % and 64.1 % for the RF and CB groups ( single procedure success ) , and noninferiority was confirmed ( risk difference , 0.010 ; 95 % confidence interval , −0.097 to 0.116 ; P=0.002 ) . Periprocedural complications for the index procedure were more frequent in the CB group ( 5.0 % RF , 12.2 % CB ; P=0.022 ) with a significant difference in phrenic nerve palsies ( 0 % RF , 5.8 % CB ; P=0.002 ) . Conclusion — This large , prospect i ve , r and omized , controlled study demonstrates noninferiority of CB ablation versus RF ablation for treating patients with paroxysmal atrial fibrillation . Clinical Trial Registration — URL : http://www . clinical trials.gov . Unique identifier : NCT00774566 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 card 
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