***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 —In patients with atrial fibrillation ( AF ) undergoing radiofrequency ( RF ) electrical disconnection of multiple pulmonary veins ( PVs ) , the incidence of late conduction recurrences has not been systematic ally determined . Methods and Results —Using a prospect ively design ed , multistep approach , we aim ed at assessing the correlation between acute achievement and chronic maintenance of electrical conduction block across RF lesions disconnecting the distal tract of the PV in 43 patients ( 52.3±8.2 years ) with AF . Forty-one left superior ( LS ) , 42 right superior ( RS ) , 25 left inferior ( LI ) , and 9 right inferior ( RI ) PVs were targeted during 108 EP procedures ( 2.6±0.5 per patient ) . Seventeen patients underwent 2 procedures , 23 patients underwent 3 procedures , and 3 patients underwent 4 procedures . During the first attempt , electrical disconnection was achieved in 112 PVs ( 95.7 % ) . During a next procedure ( time interval , 4.6±1.9 months ) , conduction recurrence was observed in 32 of 39 LSPVs ( 82.1 % ) , 29 of 40 RSPVs ( 72.5 % ) , 20 of 24 LIPVs ( 83.3 % ) , and 7 of 9 RIPV ( 77.8 % ) . After reablation at gap sites , a later procedure ( time interval , 5.1±2.4 months ) revealed a second recurrence in 13 of 22 LSPVs ( 59.1 % ) and 14 of 19 RSPVs ( 73.7 % ) . Conclusions —Conduction recurrence across disconnecting RF lesions can be observed in ≈80 % of cases 4 months after ablation . After reablation , similar recurrence rates are observed 5 months later . This high rate of late conduction recurrence may contribute significantly to AF recurrence in patients undergoing catheter ablation aim ing at disconnection of multiple PVs BACKGROUND Atrial fibrillation ( AF ) recurrence after pulmonary vein isolation ( PVI ) is associated with PV to left atrium reconduction . Effective lesion creation necessitates adequate contact force between the ablation catheter and myocardium . OBJECTIVE The purpose of this study was to study the utility of contact force-guided ablation on immediate and long-term outcomes . METHODS Seventy-five patients with highly symptomatic paroxysmal AF underwent wide circumferential PVI using an irrigated-tip radiofrequency catheter . In 25 patients , ablation was guided by real-time contact force measurements ( CF group ; SmartTouch , Biosense Webster ) . A control group of 50 patients underwent  PVI using a st and ard nonforce sensing catheter ( st and ard group ; ThermoCool , Biosense Webster ) . After PVI , all patients underwent adenosine testing to unmask dormant conduction . Patients were followed up at 3 , 6 , and 12 months and by transtelephonic monitoring as well . RESULTS Dormant conduction was unmasked and subsequently eliminated in 4 PV pairs ( 8 % ; 16 % of patients ) in the CF group and 35 PV pairs ( 35 % ; 52 % of patients ) in the st and ard group ( P = .0004 per PV pair ; P = .0029 per patient ) . The single-procedure , off-antiarrhythmic drug freedom from recurrent atrial arrhythmias at 1 year was 88 % in the CF group vs 66 % in the st and ard group ( P = .047 ) . Procedure duration and fluoroscopy time were significantly longer in the CF group ( P = .0038 and P = .0001 , respectively ) . CONCLUSION The use of real-time contact force guidance results in a significant reduction in the prevalence of dormant conduction with improved long-term freedom from recurrent arrhythmias . The utility of a contact force-guided approach requires evaluation in a long-term prospect i ve r and omized study 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 6.3 ± 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 The aim of this study was to evaluate the impact of contact force ( CF ) visualization on the incidence of low and high CF during left atrial ( LA ) mapping and pulmonary vein isolation ( PVI ) . Methods CF was assessed in 70 patients who underwent PVI .  Three highly experienced operators performed all procedures . The operators were blinded to CF in group A ( 35 patients ) , and CF was displayed in group B ( 35 patients ) . In group B , optimal CF was defined as mean CF between 10 and 39 g , and operators attempted to acquire points and ablate within this range . Results A total of 8401 mapping points were analyzed during LA mapping ( group A : 4104 , group B : 4297 ) . Low CF < 10 g and high CF ≥40 g were noted in a significantly larger number of points in group A ( 37.7 vs. 12.0 % , P < 0.001 ; 11.5 vs. 1.5 % , P < 0.001 ) . At the mitral isthmus and ridge areas , CF was significantly lower ( 7.7 vs. 12.2 g , P < 0.001 ; 5.3 vs. 11.7 g , P < 0.001 ) in group A than in group B. PVI was successfully achieved in all patients . There were significant site-dependent CF differences between the two groups . Optimal CF was achieved in significantly more applications in group B ( P < 0.001 ) . There was no significant difference in atrial fibrillation ( AF ) recurrence rates after a minimum follow-up of 1 year between the two groups in this cohort ( P = 0.24 ) . No significant peri-procedural complications occurred in either group . Conclusions CF visualization can assist in avoiding both low and high CF , which may have the potential to improve lesion formation and patient safety profile . In this study , CF-guided ablation did not affect AF recurrence Purpose We prospect ively investigated the differences in pulmonary vein reconnections ( PVRs ) and clinical outcomes between contact force (CF)-guided and conventional circumferential PV isolation ( CPVI ) of atrial fibrillation ( AF ) . Methods One hundred twenty consecutive AF patients ( 63 ± 10 years ; 88 males ) undergoing an initial CPVI were r and omized to ablation with a target CF of 20 g ( CF group ; n = 60 ) or that with operators blinded to the CF information ( blind group ; n = 60 ) . Results The CF group had fewer PVRs ( 0.67 ± 0.91/patient vs. 1.16 ± 1.16/patient ; P = 0.007 ) , a lower incidence of persistent PVRs ( 13.2 vs. 41.2 % ; P < 0.001 ) , and a shorter procedural time for the CPVI ( 50 vs. 56 min ; P = 0.019 ) than the blind group . The mean CF was higher in the CF group than the blind group ( 18.0 vs. 16.1 g ; P < 0.001 ) , with the most significant difference observed along the posterior right-sided PVs ( P-RPVs ) and anterior left-sided PVs ( A-LPVs ) . In logistic regression models , the mean CF was a negative predictor of PVRs along the P-RPVs and A-LPVs in the blind group ( odds ratios , 0.728 and 0.786 ; P < 0.001 and 0.007 ) , while no significant predictor was identified in the CF group or elsewhere in the blind group . In the Kaplan-Meier analysis , the arrhythmia-free survival rate at 12 months was 89.9 % in the CF group and 88.2 % in the blind group , respectively ( P = 0.624 ) . Conclusions CF-guided CPVI can reduce PVRs and the procedural time and be particularly beneficial along regions where a relatively low CF tends to be applied : the P-RPVs and A-LPVs . The comparable clinical outcomes may be due to the learning curve effect obtained by the CF-guided technique and repeated provocation of dormant PV conduction Purpose Lesion formation is a critical determinant of technical and clinical success of  pulmonary vein isolation .  Different catheter design s aim to enhance tissue contact during ablation to enable optimized lesion formation . We analyzed procedural characteristics and predictors of clinical success in patients ablated with three different contemporary ablation catheters .  Methods Two hundred sixty-eight sequentially included patients receiving pulmonary vein isolation ( PVI ) with conventional ( n = 122 ) , contact-force ( n = 96 ) and flexible-tip ( n = 60 ) catheters  were followed for a median of 14.1 months with 7d-Holter-monitoring and TTE at 3 , 6 , 12 , and 24 months . Baseline characteristics and follow-up times were homogeneous across all groups . Results Multivariable Cox proportional hazard regression for arrhythmia recurrence demonstrated a favorable hazard ratio for contact-force and flexible-tip catheters vs. conventional open irrigation catheters .  Procedure time and fluoroscopy time were shorter for contact-force and flexible-tip catheters versus conventional cath 
    Output:
    
Conclusion : CF‐guided RF catheter ablation was associated with a significant AF/atrial tachycardia‐free survival  benefit compared with non‐CF‐guided ablation in patients with paroxysmal AF rather than persistent AF .
In addition , CF‐guided ablation strategy also reduced the procedure time , fluoroscopy time , as well as RF time despite no distinct effect on the alleviation of procedure‐related complications