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 —Radiofrequency ( RF ) catheter ablation is limited by thromboembolic complications . The objective of this study was to compare the incidence and characteristics of thrombi complicating RF and cryoenergy ablation , a novel technology for the catheter-based treatment of arrhythmias . Methods and Results —Ablation  lesions ( n=197 ) were performed in 22 mongrel dogs at right atrial , right ventricular , and left ventricular sites preselected by a r and omized factorial design devised to compare RF ablation with cryocatheter configurations of varying sizes ( 7F and 9F ) , cooling rates ( −1 ° C/s , −5 ° C/s , and −20 ° C/s ) and target temperatures ( −55 ° C and −75 ° C ) . Animals were pretreated with acetylsalicylic acid and received intraprocedural intravenous unfractionated heparin . Seven days after ablation , the incidence of thrombus formation was significantly higher with RF than with cryoablation ( 75.8 % versus 30.1 % , P = 0.0005 ) . In a multiple regression model , RF energy remained an independent predictor of thrombus formation compared with cryoenergy ( OR , 5.6 ; 95 % CI , 1.7 , 18.1;P = 0.0042 ) . Thrombus volume was also significantly greater with RF than with cryoablation ( median , 2.8 versus 0.0 mm3;P < 0.0001 ) . More voluminous thrombi were associated with larger RF lesions , but cryolesion dimensions were not predictive of thrombus size . Conclusions —RF energy is significantly more thrombogenic than cryoenergy , with a higher incidence of thrombus formation and larger thrombus volumes . The extent of hyperthermic tissue injury is positively correlated with thrombus bulk , whereas cryoenergy lesion size does not predict thrombus volume , most likely reflecting intact tissue ultrastructure with endothelial cell preservation 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 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 ) 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 — 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 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 ACCF : American College of Cardiology Foundation ACCP : American College of Chest Physicians ACS : acute coronary syndrome ACT : Atrial arrhythmia Conversion Trial ADONIS : American – Australian – African trial with DronedarONe In atrial fibrillation or flutter for the maintenance of Sinus rhythm AF : atrial fibrillation AHA : American Heart Association AND ROMEDA : ANtiarrhythmic trial with DROnedarone in Moderate-to-severe congestive heart failure Evaluating morbidity DecreAse APHRS : Asia Pacific Heart Rhythm Society aPTT : activated partial thromboplastin time ARB : angiotensin-receptor blocker ARISTOTLE : Apixaban for Reduction In STroke and Other ThromboemboLic Events in atrial fibrillation ATHENA : A placebo-controlled , double-blind , parallel arm Trial to assess the efficacy of droned 
    Output:
    
agent
Conclusions Compared with RF ablation , cryoablation present a comparable long-term AF/atrial tachycardial-free survival and procedure-related adverse events .
Meanwhile , cryoablation markedly shorten the procedure time , nonetheless , with negligible impact on the fluoroscopy time
***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 —Radiofrequency ( RF ) catheter ablation is limited by thromboembolic complications . The objective of this study was to compare the incidence and characteristics of thrombi complicating RF and cryoenergy ablation , a novel technology for the catheter-based treatment of arrhythmias . Methods and Results —Ablation  lesions ( n=197 ) were performed in 22 mongrel dogs at right atrial , right ventricular , and left ventricular sites preselected by a r and omized factorial design devised to compare RF ablation with cryocatheter configurations of varying sizes ( 7F and 9F ) , cooling rates ( −1 ° C/s , −5 ° C/s , and −20 ° C/s ) and target temperatures ( −55 ° C and −75 ° C ) . Animals were pretreated with acetylsalicylic acid and received intraprocedural intravenous unfractionated heparin . Seven days after ablation , the incidence of thrombus formation was significantly higher with RF than with cryoablation ( 75.8 % versus 30.1 % , P = 0.0005 ) . In a multiple regression model , RF energy remained an independent predictor of thrombus formation compared with cryoenergy ( OR , 5.6 ; 95 % CI , 1.7 , 18.1;P = 0.0042 ) . Thrombus volume was also significantly greater with RF than with cryoablation ( median , 2.8 versus 0.0 mm3;P < 0.0001 ) . More voluminous thrombi were associated with larger RF lesions , but cryolesion dimensions were not predictive of thrombus size . Conclusions —RF energy is significantly more thrombogenic than cryoenergy , with a higher incidence of thrombus formation and larger thrombus volumes . The extent of hyperthermic tissue injury is positively correlated with thrombus bulk , whereas cryoenergy lesion size does not predict thrombus volume , most likely reflecting intact tissue ultrastructure with endothelial cell preservation 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 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 ) 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 — 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 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 ACCF : American College of Cardiology Foundation ACCP : American College of Chest Physicians ACS : acute coronary syndrome ACT : Atrial arrhythmia Conversion Trial ADONIS : American – Australian – African trial with DronedarONe In atrial fibrillation or flutter for the maintenance of Sinus rhythm AF : atrial fibrillation AHA : American Heart Association AND ROMEDA : ANtiarrhythmic trial with DROnedarone in Moderate-to-severe congestive heart failure Evaluating morbidity DecreAse APHRS : Asia Pacific Heart Rhythm Society aPTT : activated partial thromboplastin time ARB : angiotensin-receptor blocker ARISTOTLE : Apixaban for Reduction In STroke and Other ThromboemboLic Events in atrial fibrillation ATHENA : A placebo-controlled , double-blind , parallel arm Trial to assess the efficacy of droned 
    Output:
    