human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Aims Contact force ( CF ) catheters provide catheter-tissue contact information to improve outcome of  pulmonary vein isolation ( PVI ) in paroxysmal atrial fibrillation ( PAF ) . We evaluated different target-CF values for achievement of the additional endpoint of an unexcitable ablation line . Methods A total of 106 patients undergoing PVI  were r and omized into three groups ( G ) ( G1 : target-CF 15 g , G2 : target-CF 10 g , G3 : CF concealed from operator ) . The PVI encircling line was divided into predefined sections . Excitable tissue along the PVI-line identified by high output pacing ( 10 V , 2 ms ) was targeted for further ablation . Results Mean average CF was 17.4 ± 4.7 g ( G1 ) vs. 12.3 ± 6.0 g ( G2 ) vs. 11.1 ± 6.5 g ( G 3 ) ( p < 0.001 ) . Primary unexcitable ablation lines were found in 38.6 , 19.4 and 5.7 % ( G1 , G2 , G3 respectively ; G1 vs. G2 p < 0.05 , G1 vs. G3 p < 0.001 , G2 vs. G3 ns ) . Additional radiofrequency (RF)-energy to achieve unexcitability was lowest in G1 ( 3.6 ± 3.1 kJ vs. 8.6 ± 7.2 kJ ( G2 ) and 10.4 ± 6.7 ( G3 ) , p ≤ 0.001 , G2 vs. G3 ns ) with accordingly lowest additional RF applications in G1 ( 3.0 ± 2.6 vs. 7.0 ± 5.4 in G2 and 8.4 ± 4.0 in G3 ; G1 vs. G2 and G3 , p < 0.001 , G 2 vs. G 3 ns ) . Sections along ablation lines with low initial CF were most likely to reveal excitability . Single procedure success was 81.9 vs. 73.5 vs. 71.4 % ( G 1 , 2 and 3 , p = 0.6 ) during 437 ± 254 day follow-up . Conclusion Higher tip-to-tissue CF during PVI facilitates the achievement of an unexcitable ablation line , requiring less additional RF-energy Aims We have recently shown that a contact force (CF)-guided ablation protocol respecting region-specific criteria of lesion contiguity and lesion depth ( ' CLOSE ' protocol ) is associated with high incidence of acute durable pulmonary vein ( PV ) isolation ( PVI ) and a high single-procedure arrhythmia-free survival at 1 year . In the present study , we compared efficiency , safety , and efficacy of ' CLOSE'-guided PVI to conventional CF-guided PVI ( CONV-CF ) . Methods and results Fifty consecutive paroxysmal atrial fibrillation ( AF ) patients underwent PV encircling using a CF-sensing catheter  targeting an interlesion distance ( ILD ) ≤6 mm and ablation index ( AI ) ≥400 and ≥550 at posterior and anterior wall ( ' CLOSE ' group ) . Results were compared to the last 50 patients undergoing ' CONV-CF ' . All patients underwent adenosine testing after PVI .  Arrhythmia recurrence was defined as any atrial tachyarrhythmia ( ATA ) > 30 s on Holter at 3 , 6 , and 12 months . Clinical characteristics did not differ . Contact force variability was comparable in between both groups ( proportion of applications with intermittent contact 2 % in ' CLOSE ' vs. 1 % in CONV-CF , P = 0.67 ) . In the ' CLOSE ' group , procedure time and radiofrequency ( RF ) time per circle were shorter ( respectively 149 ± 33 min vs. 192 ± 42 min , P < 0.0001 and 18 ± 4 min vs 28 ± 7.5 min , P < 0.0001 ) and incidence of adenosine-proof isolation was higher ( 97 % vs. 82 % , P < 0.001 ) . No complications were observed in the ' CLOSE ' group , one tamponade in the ' CONV-CF ' group . At 12 months , single-procedure freedom from ATA was 94 % in ' CLOSE ' vs. 80 % in ' CONV-CF ' group ( P < 0.05 ) . In both groups , the majority of reconnections at repeat were associated with either ILD > 6 mm and /or AI < 400/550 ( 100 % vs. 83 % , P = 0.99 ) . Conclusion ' CLOSE'-guided PVI improves procedural and 1 year outcome in CF-guided PVI while shortening procedure time . Improvement can not be explained by differences in CF variability and is most likely due to the strict application of criteria for contiguity and ablation index . A r and omized controlled trial is needed to exclude the possible contribution of a learning curve Introduction Comparative data of early recurrence rates of atrial fibrillation ( ERAF )  following second-generation cryoballoon ( CB-G2 ) and radiofrequency current ( RFC ) ablation for pulmonary vein isolation ( PVI ) in paroxysmal AF ( PAF ) are rare . We r and omized PAF patients into either PVI with CB-G2 ( group 1 ) or PVI with a combined RFC-approach applying contact force ( CF ) with the endpoint of unexcitability ( group 2 ) to investigate ERAF . Methods and results In group 1 ( n = 30 ) , CB-G2-PVI was performed . After CF-PVI in group 2 ( n = 30 ) , bipolar pacing on the ablation line and additional ablation until unexcitability was conducted . Follow-up included 48 h of in-hospital monitoring followed by 5-day Holter ECGs 1 , 2 , 3 , 6 , 12 months postablation to evaluate ERAF . Acute PVI was reached in 100 % of group 2 and in 99 % of group 1 . Shorter procedure duration s ( 98.0 ± 21.9 vs. 114.3 ± 18.7 min , P < 0.05 ) but extended fluoroscopy times ( 15.4 ± 3.9 vs. 10.0 ± 4.3 min , P < 0.05 ) were found in the CB-G2 group . Ten non-severe complications occurred ( 6 vs. 4 in group 1 and 2 , P = 0.73 ) . In group 2 , five patients suffered from ERAF vs. seven patients in group 1 ( P = 0.67 ) . The time until the occurrence of ERAF was shorter in group 2 ( 1 day ( q1-q3 : 1 - 4.5 ) ) when compared with group 1 ( 22 ( q1-q3 : 6 - 54 ) days , P = 0.025 ) . Conclusion ERAF rates were equal among groups ; however , they occurred earlier in the initial phase after RFC ablation when compared with CB-G2 . PVI utilizing cryoablation is associated with shorter procedure duration s but extended fluoroscopy time while being similarly secure BACKGROUND Pulmonary vein isolation ( PVI ) is a well-established treatment of atrial fibrillation ( AF ) , with contact force (CF)-sensing catheters joining 3-dimensional mapping systems and image integration as technological advancements over the last decade . OBJECTIVE The purpose of this study was to analyze trends in radiation exposure for AF ablation over the last 12 years at our center . METHODS We review ed prospect ively collected data of 2344 consecutive PVI procedures for either paroxysmal or persistent AF between January 2004 and December 2015 . During this period , all cases used 3-dimensional mapping systems , with 8 software and 2 hardware up grade s. Primary endpoints were fluoroscopy time , absorbed dose ( Air Kerma in mGy ) , and effective dose ( mSv ) . RESULTS In total , 1914 patients underwent initial PVI , and 430 patients underwent redo PVI using radiofrequency energy . Fluoroscopy time , and absorbed and effective doses significantly and progressively decreased over the 12-year period for initial PVI as follows : 2004 - 2006 : 61 ± 27 minutes ; 2007 - 2009 : 46 ± 14 minutes , 1365 ± 1369 mGy , 11.3 ± 12.5 mSv ; 2010 - 2012 : 31 ± 11 , 464 ± 339 mGy , 9.0 ± 10.4 mSv ; and 2013 - 2015 : 17 ± 9 minutes , 304 ± 758 mGy , 5.5 ± 6.7 mSv . CF-sensing catheters were used for 357/508 PVI only cases between 2014 and 2015 . Fluoroscopy times ( 11 ± 5 vs 21 ± 8 minutes ; P < .001 ) and absorbed dose ( 200 ± 524 vs 470 ± 1326 mGy ; P = .004 ) were significantly shorter with this catheter . CONCLUSION Radiation exposure has dramatically decreased over the last decade for PVI and is related to operator experience , annual case volume , technology evolution , and more recently CF-sensing catheters . This has significant implication s for both patient and operator long-term risk BACKGROUND Contact force ( CF ) information may improve the safety and efficacy of ablation for paroxysmal atrial fibrillation ( PAF ) . OBJECTIVE The purpose of this study was to assess the impact of CF data on ablation for PAF . METHODS Patients undergoing first-time PAF ablation were r and omized at 7 UK centers to ablation with ( CF-on ) or without ( CF-off ) CF data available to the operator , using the same ablation catheter and mapping system . An ablation CF of 5 - 40 g was targeted . Pulmonary vein ( PV ) reconnection was assessed with adenosine at 60 minutes . Follow-up for arrhythmia recurrence was for 1 year with 7-day Holter recordings at 6 and 12 months . RESULTS One hundred seventeen patients were studied ( 59 CF-on , 58 CF-off ) . In the CF-on group , a reduction in acute PV reconnection rates ( 22 % vs 32 % , P = .03 ) but no significant difference in 1-year success rates off antiarrhythmic drugs ( 49 % vs 52 % , P = .9 ) was observed . There was no difference in major complication rates : 2 of 59 ( 3 % ) CF-on , 3 of 58 ( 5 % ) CF-off ( P = .7 ) . Procedural and fluoroscopy times were not significantly different ( P>.5 ) . Overall mean CFs per ablation were not different between groups ( 13.4 [9.1 - 19.6]g CF-on , 13.4 [7.4 - 22.4]g CF-off , P = .5 ) , but a greater proportion of readings in the CF-on group were in the target range ( 80 % vs 68 % , P<.001 ) . CONCLUSION This r and omized multicenter study demonstrated that CF data availability was associated with reduced acute PV reconnection but not improved 1-year success rates , procedural and fluoroscopy times , or complication rates . There was a reduction in extremes of CF , above and below the study target range , suggesting greater CF control during ablation 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. 
    Output:
    
agent
Complication rates , including cardiac tamponade , did not differ between groups .
Compared with the use of other catheters , AF ablation using the CF-sensing ST catheter for AF is associated with improved success rates , shorter procedure and fluoroscopy times and similar safety profile
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Aims Contact force ( CF ) catheters provide catheter-tissue contact information to improve outcome of  pulmonary vein isolation ( PVI ) in paroxysmal atrial fibrillation ( PAF ) . We evaluated different target-CF values for achievement of the additional endpoint of an unexcitable ablation line . Methods A total of 106 patients undergoing PVI  were r and omized into three groups ( G ) ( G1 : target-CF 15 g , G2 : target-CF 10 g , G3 : CF concealed from operator ) . The PVI encircling line was divided into predefined sections . Excitable tissue along the PVI-line identified by high output pacing ( 10 V , 2 ms ) was targeted for further ablation . Results Mean average CF was 17.4 ± 4.7 g ( G1 ) vs. 12.3 ± 6.0 g ( G2 ) vs. 11.1 ± 6.5 g ( G 3 ) ( p < 0.001 ) . Primary unexcitable ablation lines were found in 38.6 , 19.4 and 5.7 % ( G1 , G2 , G3 respectively ; G1 vs. G2 p < 0.05 , G1 vs. G3 p < 0.001 , G2 vs. G3 ns ) . Additional radiofrequency (RF)-energy to achieve unexcitability was lowest in G1 ( 3.6 ± 3.1 kJ vs. 8.6 ± 7.2 kJ ( G2 ) and 10.4 ± 6.7 ( G3 ) , p ≤ 0.001 , G2 vs. G3 ns ) with accordingly lowest additional RF applications in G1 ( 3.0 ± 2.6 vs. 7.0 ± 5.4 in G2 and 8.4 ± 4.0 in G3 ; G1 vs. G2 and G3 , p < 0.001 , G 2 vs. G 3 ns ) . Sections along ablation lines with low initial CF were most likely to reveal excitability . Single procedure success was 81.9 vs. 73.5 vs. 71.4 % ( G 1 , 2 and 3 , p = 0.6 ) during 437 ± 254 day follow-up . Conclusion Higher tip-to-tissue CF during PVI facilitates the achievement of an unexcitable ablation line , requiring less additional RF-energy Aims We have recently shown that a contact force (CF)-guided ablation protocol respecting region-specific criteria of lesion contiguity and lesion depth ( ' CLOSE ' protocol ) is associated with high incidence of acute durable pulmonary vein ( PV ) isolation ( PVI ) and a high single-procedure arrhythmia-free survival at 1 year . In the present study , we compared efficiency , safety , and efficacy of ' CLOSE'-guided PVI to conventional CF-guided PVI ( CONV-CF ) . Methods and results Fifty consecutive paroxysmal atrial fibrillation ( AF ) patients underwent PV encircling using a CF-sensing catheter  targeting an interlesion distance ( ILD ) ≤6 mm and ablation index ( AI ) ≥400 and ≥550 at posterior and anterior wall ( ' CLOSE ' group ) . Results were compared to the last 50 patients undergoing ' CONV-CF ' . All patients underwent adenosine testing after PVI .  Arrhythmia recurrence was defined as any atrial tachyarrhythmia ( ATA ) > 30 s on Holter at 3 , 6 , and 12 months . Clinical characteristics did not differ . Contact force variability was comparable in between both groups ( proportion of applications with intermittent contact 2 % in ' CLOSE ' vs. 1 % in CONV-CF , P = 0.67 ) . In the ' CLOSE ' group , procedure time and radiofrequency ( RF ) time per circle were shorter ( respectively 149 ± 33 min vs. 192 ± 42 min , P < 0.0001 and 18 ± 4 min vs 28 ± 7.5 min , P < 0.0001 ) and incidence of adenosine-proof isolation was higher ( 97 % vs. 82 % , P < 0.001 ) . No complications were observed in the ' CLOSE ' group , one tamponade in the ' CONV-CF ' group . At 12 months , single-procedure freedom from ATA was 94 % in ' CLOSE ' vs. 80 % in ' CONV-CF ' group ( P < 0.05 ) . In both groups , the majority of reconnections at repeat were associated with either ILD > 6 mm and /or AI < 400/550 ( 100 % vs. 83 % , P = 0.99 ) . Conclusion ' CLOSE'-guided PVI improves procedural and 1 year outcome in CF-guided PVI while shortening procedure time . Improvement can not be explained by differences in CF variability and is most likely due to the strict application of criteria for contiguity and ablation index . A r and omized controlled trial is needed to exclude the possible contribution of a learning curve Introduction Comparative data of early recurrence rates of atrial fibrillation ( ERAF )  following second-generation cryoballoon ( CB-G2 ) and radiofrequency current ( RFC ) ablation for pulmonary vein isolation ( PVI ) in paroxysmal AF ( PAF ) are rare . We r and omized PAF patients into either PVI with CB-G2 ( group 1 ) or PVI with a combined RFC-approach applying contact force ( CF ) with the endpoint of unexcitability ( group 2 ) to investigate ERAF . Methods and results In group 1 ( n = 30 ) , CB-G2-PVI was performed . After CF-PVI in group 2 ( n = 30 ) , bipolar pacing on the ablation line and additional ablation until unexcitability was conducted . Follow-up included 48 h of in-hospital monitoring followed by 5-day Holter ECGs 1 , 2 , 3 , 6 , 12 months postablation to evaluate ERAF . Acute PVI was reached in 100 % of group 2 and in 99 % of group 1 . Shorter procedure duration s ( 98.0 ± 21.9 vs. 114.3 ± 18.7 min , P < 0.05 ) but extended fluoroscopy times ( 15.4 ± 3.9 vs. 10.0 ± 4.3 min , P < 0.05 ) were found in the CB-G2 group . Ten non-severe complications occurred ( 6 vs. 4 in group 1 and 2 , P = 0.73 ) . In group 2 , five patients suffered from ERAF vs. seven patients in group 1 ( P = 0.67 ) . The time until the occurrence of ERAF was shorter in group 2 ( 1 day ( q1-q3 : 1 - 4.5 ) ) when compared with group 1 ( 22 ( q1-q3 : 6 - 54 ) days , P = 0.025 ) . Conclusion ERAF rates were equal among groups ; however , they occurred earlier in the initial phase after RFC ablation when compared with CB-G2 . PVI utilizing cryoablation is associated with shorter procedure duration s but extended fluoroscopy time while being similarly secure BACKGROUND Pulmonary vein isolation ( PVI ) is a well-established treatment of atrial fibrillation ( AF ) , with contact force (CF)-sensing catheters joining 3-dimensional mapping systems and image integration as technological advancements over the last decade . OBJECTIVE The purpose of this study was to analyze trends in radiation exposure for AF ablation over the last 12 years at our center . METHODS We review ed prospect ively collected data of 2344 consecutive PVI procedures for either paroxysmal or persistent AF between January 2004 and December 2015 . During this period , all cases used 3-dimensional mapping systems , with 8 software and 2 hardware up grade s. Primary endpoints were fluoroscopy time , absorbed dose ( Air Kerma in mGy ) , and effective dose ( mSv ) . RESULTS In total , 1914 patients underwent initial PVI , and 430 patients underwent redo PVI using radiofrequency energy . Fluoroscopy time , and absorbed and effective doses significantly and progressively decreased over the 12-year period for initial PVI as follows : 2004 - 2006 : 61 ± 27 minutes ; 2007 - 2009 : 46 ± 14 minutes , 1365 ± 1369 mGy , 11.3 ± 12.5 mSv ; 2010 - 2012 : 31 ± 11 , 464 ± 339 mGy , 9.0 ± 10.4 mSv ; and 2013 - 2015 : 17 ± 9 minutes , 304 ± 758 mGy , 5.5 ± 6.7 mSv . CF-sensing catheters were used for 357/508 PVI only cases between 2014 and 2015 . Fluoroscopy times ( 11 ± 5 vs 21 ± 8 minutes ; P < .001 ) and absorbed dose ( 200 ± 524 vs 470 ± 1326 mGy ; P = .004 ) were significantly shorter with this catheter . CONCLUSION Radiation exposure has dramatically decreased over the last decade for PVI and is related to operator experience , annual case volume , technology evolution , and more recently CF-sensing catheters . This has significant implication s for both patient and operator long-term risk BACKGROUND Contact force ( CF ) information may improve the safety and efficacy of ablation for paroxysmal atrial fibrillation ( PAF ) . OBJECTIVE The purpose of this study was to assess the impact of CF data on ablation for PAF . METHODS Patients undergoing first-time PAF ablation were r and omized at 7 UK centers to ablation with ( CF-on ) or without ( CF-off ) CF data available to the operator , using the same ablation catheter and mapping system . An ablation CF of 5 - 40 g was targeted . Pulmonary vein ( PV ) reconnection was assessed with adenosine at 60 minutes . Follow-up for arrhythmia recurrence was for 1 year with 7-day Holter recordings at 6 and 12 months . RESULTS One hundred seventeen patients were studied ( 59 CF-on , 58 CF-off ) . In the CF-on group , a reduction in acute PV reconnection rates ( 22 % vs 32 % , P = .03 ) but no significant difference in 1-year success rates off antiarrhythmic drugs ( 49 % vs 52 % , P = .9 ) was observed . There was no difference in major complication rates : 2 of 59 ( 3 % ) CF-on , 3 of 58 ( 5 % ) CF-off ( P = .7 ) . Procedural and fluoroscopy times were not significantly different ( P>.5 ) . Overall mean CFs per ablation were not different between groups ( 13.4 [9.1 - 19.6]g CF-on , 13.4 [7.4 - 22.4]g CF-off , P = .5 ) , but a greater proportion of readings in the CF-on group were in the target range ( 80 % vs 68 % , P<.001 ) . CONCLUSION This r and omized multicenter study demonstrated that CF data availability was associated with reduced acute PV reconnection but not improved 1-year success rates , procedural and fluoroscopy times , or complication rates . There was a reduction in extremes of CF , above and below the study target range , suggesting greater CF control during ablation 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. 
    Output:
    