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 —Atrial  fibrillation ( AF ) ablation  is increasingly used in clinical practice . We aim ed to study the natural history and long-term outcomes of ablated AF . Methods and Results —We followed 831 patients after pulmonary vein isolation ( PVI ) performed in 2005 . We documented clinical outcomes using our prospect i ve AF registry with most recent up date on this group of patients in October 2009 . In the first year after ablation , 23.8 % had early recurrence . Over long-term follow-up ( 55 months ) , only 8.9 % had late arrhythmia recurrence defined as occurring beyond the first year after ablation . Repeat ablations in patients with late recurrence revealed conduction recovery in at least 1 of the previously isolated PVs in all of them and right-sided triggers with isoproterenol testing in 55.6 % . At last follow-up , clinical improvement was 89.9 % ( 79.4 % arrhythmia-free off antiarrhythmic drugs and 10.5 % with AF controlled with antiarrhythmic drugs ) . Only 4.6 % continued to have drug-resistant AF . It was possible to safely discontinue anticoagulation in a substantial proportion of patients with no recurrence in the year after ablation ( CHADS score ⩽2 , stroke incidence of 0.06 % per year ) . The procedure-related complication rate was very low . Conclusions —Pulmonary vein isolation is safe and efficacious for long-term maintenance of sinus rhythm and control of symptoms in patients with drug-resistant AF . It obviates the need for antiarrhythmic drugs , negative dromotropic agents , and anticoagulants in a substantial proportion of patients 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 ) 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 Electrode-tissue contact is crucial for adequate lesion formation in radiofrequency catheter ablation ( RFCA ) . OBJECTIVE We assessed the impact of direct catheter force measurement on acute procedural parameters during RFCA of atrial fibrillation ( AF ) . METHODS Fifty consecutive patients ( 28 male ) with paroxysmal AF who underwent their first procedure of circumferential pulmonary vein ( PV ) isolation ( PVI ) were assigned to either RFCA using ( 1 ) a st and ard 3.5-mm open-irrigated-tip catheter or ( 2 ) a catheter with contact force measurement capabilities . Using the endpoint of PVI with entry and exit block , acute procedural parameters were assessed . RESULTS Procedural data showed a remarkable decline in ablation time ( radiofrequency time needed for PVI ) from 50.5 ± 15.9 to 39.0 ± 11.0 minutes ( P = 0.007 ) with a reduction in overall procedure duration from 185 ± 46 to 154 ± 39 minutes ( P = 0.022 ) . In parallel , the total energy delivered could be significantly reduced from 70,926 ± 19,470 to 58,511 ± 14,655 Ws ( P = 0.019 ) . The number of acute PV reconnections declined from 36 % to 12 % ( P = 0.095 ) . CONCLUSIONS The use of contact force sensing technology is able to significantly reduce ablation and procedure times in PVI . In addition , energy delivery is substantially reduced by avoiding radiofrequency ablation in positions with insufficient surface contact . Procedural efficacy and safety of this new feature have to be evaluated in larger cohorts INTRODUCTION The additional benefit of contact force ( CF ) technology during pulmonary vein isolation ( PVI ) for paroxysmal atrial fibrillation ( AF ) to improve mid-term clinical outcome is unclear . METHODS AND RESULTS Eligible patients with symptomatic paroxysmal AF were enrolled in this prospect i ve trial , comparing circular antral catheter ablation ( guided by Carto 3 System , Biosense Webster ) using either a new open-irrigated CF catheter ( SmartTouch Thermocool , Biosense Webster ) ( CF group ) or a non-CF open-irrigated catheter ( EZ Steer Thermocool , Biosense Webster ) ( control group ) . Overall , 30 patients were enrolled in each group , with a st and ardized 12-month follow-up , free of antiarrhythmic therapy . Demographic , cardiovascular and anatomic characteristics were similar in both groups . Though complete PVI was eventually achieved in all cases in both groups , success using an exclusive anatomic approach was 80.0 % in CF group versus 36.7 % in control group ( P < 0.0001 ) . CF use was associated with significant reductions in fluoroscopy exposure ( P < 0.01 ) and radiofrequency time ( P = 0.01 ) . The incidence rates of AF recurrence were 10.5 % ( 95 % CI , 1.38 - 22.4 ) in the CF group , and 35.9 % ( 95 % CI , 12.4 - 59.4 ) in the control group ( log rank test , P = 0.04 ) . After adjustment on potential confounders , the use of CF catheter was found to be associated with a lower AF recurrence ( OR 0.18 , 95 % CI 0.04 - 0.94 , P = 0.04 ) . CONCLUSION Our findings suggest a potential benefit of real-time CF sensing technology , in reducing AF recurrence during the first year after PVI BACKGROUND Contact force ( CF ) sensing catheters provide advantages with regard to safety and efficacy . This study aim ed to evaluate if CF catheters reduce cardiac perforations and other major complications and offer equal safety compared to the magnetic navigation system ( MNS ) . METHODS Data from 1.517 ablation procedures from our prospect i ve registry was analyzed . Ablations were performed using either CF guided catheters ( CF group , n=248 ) , non-CF catheters ( NCF group , n=813 ) , or MNS ( n=456 ) . Four subgroups were analyzed : atrial fibrillation ( AF , n=557 ) , supraventricular tachycardia ( SVT , n=715 ) , ventricular tachycardia ( VT , n=190 ) and patients with congenital heart defects ( CHD , n=55 ) . The primary endpoint of this study was incidence of cardiac perforation . Secondary endpoints were major and minor complications within 30 days of the procedure . RESULTS Complications occurred in 11.3 % ( n=172 ) of the procedures . In 2.8 % ( n=43 ) a major complication occurred , 0.9 % ( n=13 ) had a perforation , 8.5 % ( n=129 ) had a minor complication and 2 patients died ( 0.1 % ) . No cardiac perforation occurred in the CF group , which was significantly different from NCF procedures ( 0.0 % vs. 1.6 % ; relative risk 0.76 , 95 % CI 0.74 - 0.79 , P=0.031 ) and equal to MNS ( 0.0 % ) . This was also observed in the AF subgroup ( 0.0 % vs. 3.3 % ; RR 0.67 , 95 % CI 0.63 - 0.72 , P=0.021 ) , and the occurrence of major complications was lower for CF versus NCF procedures ( 2.1 % vs. 7.8 % , P=0.010 ) . CONCLUSIONS CF-guided catheter ablation is superior to NCF with regard to procedural safety and avoidance of cardiac perforation . This difference is due to a reduction of cardiac perforation and major complications in the AF subgroup 
    Output:
    
agent
In conclusion , this meta- analysis shows that the use of CF technology decreases AF recurrence at a median follow-up of 12 months and also led to decreased use of RF during ablation .
There was no difference in total procedure length and fluoroscopy exposure
***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 —Atrial  fibrillation ( AF ) ablation  is increasingly used in clinical practice . We aim ed to study the natural history and long-term outcomes of ablated AF . Methods and Results —We followed 831 patients after pulmonary vein isolation ( PVI ) performed in 2005 . We documented clinical outcomes using our prospect i ve AF registry with most recent up date on this group of patients in October 2009 . In the first year after ablation , 23.8 % had early recurrence . Over long-term follow-up ( 55 months ) , only 8.9 % had late arrhythmia recurrence defined as occurring beyond the first year after ablation . Repeat ablations in patients with late recurrence revealed conduction recovery in at least 1 of the previously isolated PVs in all of them and right-sided triggers with isoproterenol testing in 55.6 % . At last follow-up , clinical improvement was 89.9 % ( 79.4 % arrhythmia-free off antiarrhythmic drugs and 10.5 % with AF controlled with antiarrhythmic drugs ) . Only 4.6 % continued to have drug-resistant AF . It was possible to safely discontinue anticoagulation in a substantial proportion of patients with no recurrence in the year after ablation ( CHADS score ⩽2 , stroke incidence of 0.06 % per year ) . The procedure-related complication rate was very low . Conclusions —Pulmonary vein isolation is safe and efficacious for long-term maintenance of sinus rhythm and control of symptoms in patients with drug-resistant AF . It obviates the need for antiarrhythmic drugs , negative dromotropic agents , and anticoagulants in a substantial proportion of patients 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 ) 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 Electrode-tissue contact is crucial for adequate lesion formation in radiofrequency catheter ablation ( RFCA ) . OBJECTIVE We assessed the impact of direct catheter force measurement on acute procedural parameters during RFCA of atrial fibrillation ( AF ) . METHODS Fifty consecutive patients ( 28 male ) with paroxysmal AF who underwent their first procedure of circumferential pulmonary vein ( PV ) isolation ( PVI ) were assigned to either RFCA using ( 1 ) a st and ard 3.5-mm open-irrigated-tip catheter or ( 2 ) a catheter with contact force measurement capabilities . Using the endpoint of PVI with entry and exit block , acute procedural parameters were assessed . RESULTS Procedural data showed a remarkable decline in ablation time ( radiofrequency time needed for PVI ) from 50.5 ± 15.9 to 39.0 ± 11.0 minutes ( P = 0.007 ) with a reduction in overall procedure duration from 185 ± 46 to 154 ± 39 minutes ( P = 0.022 ) . In parallel , the total energy delivered could be significantly reduced from 70,926 ± 19,470 to 58,511 ± 14,655 Ws ( P = 0.019 ) . The number of acute PV reconnections declined from 36 % to 12 % ( P = 0.095 ) . CONCLUSIONS The use of contact force sensing technology is able to significantly reduce ablation and procedure times in PVI . In addition , energy delivery is substantially reduced by avoiding radiofrequency ablation in positions with insufficient surface contact . Procedural efficacy and safety of this new feature have to be evaluated in larger cohorts INTRODUCTION The additional benefit of contact force ( CF ) technology during pulmonary vein isolation ( PVI ) for paroxysmal atrial fibrillation ( AF ) to improve mid-term clinical outcome is unclear . METHODS AND RESULTS Eligible patients with symptomatic paroxysmal AF were enrolled in this prospect i ve trial , comparing circular antral catheter ablation ( guided by Carto 3 System , Biosense Webster ) using either a new open-irrigated CF catheter ( SmartTouch Thermocool , Biosense Webster ) ( CF group ) or a non-CF open-irrigated catheter ( EZ Steer Thermocool , Biosense Webster ) ( control group ) . Overall , 30 patients were enrolled in each group , with a st and ardized 12-month follow-up , free of antiarrhythmic therapy . Demographic , cardiovascular and anatomic characteristics were similar in both groups . Though complete PVI was eventually achieved in all cases in both groups , success using an exclusive anatomic approach was 80.0 % in CF group versus 36.7 % in control group ( P < 0.0001 ) . CF use was associated with significant reductions in fluoroscopy exposure ( P < 0.01 ) and radiofrequency time ( P = 0.01 ) . The incidence rates of AF recurrence were 10.5 % ( 95 % CI , 1.38 - 22.4 ) in the CF group , and 35.9 % ( 95 % CI , 12.4 - 59.4 ) in the control group ( log rank test , P = 0.04 ) . After adjustment on potential confounders , the use of CF catheter was found to be associated with a lower AF recurrence ( OR 0.18 , 95 % CI 0.04 - 0.94 , P = 0.04 ) . CONCLUSION Our findings suggest a potential benefit of real-time CF sensing technology , in reducing AF recurrence during the first year after PVI BACKGROUND Contact force ( CF ) sensing catheters provide advantages with regard to safety and efficacy . This study aim ed to evaluate if CF catheters reduce cardiac perforations and other major complications and offer equal safety compared to the magnetic navigation system ( MNS ) . METHODS Data from 1.517 ablation procedures from our prospect i ve registry was analyzed . Ablations were performed using either CF guided catheters ( CF group , n=248 ) , non-CF catheters ( NCF group , n=813 ) , or MNS ( n=456 ) . Four subgroups were analyzed : atrial fibrillation ( AF , n=557 ) , supraventricular tachycardia ( SVT , n=715 ) , ventricular tachycardia ( VT , n=190 ) and patients with congenital heart defects ( CHD , n=55 ) . The primary endpoint of this study was incidence of cardiac perforation . Secondary endpoints were major and minor complications within 30 days of the procedure . RESULTS Complications occurred in 11.3 % ( n=172 ) of the procedures . In 2.8 % ( n=43 ) a major complication occurred , 0.9 % ( n=13 ) had a perforation , 8.5 % ( n=129 ) had a minor complication and 2 patients died ( 0.1 % ) . No cardiac perforation occurred in the CF group , which was significantly different from NCF procedures ( 0.0 % vs. 1.6 % ; relative risk 0.76 , 95 % CI 0.74 - 0.79 , P=0.031 ) and equal to MNS ( 0.0 % ) . This was also observed in the AF subgroup ( 0.0 % vs. 3.3 % ; RR 0.67 , 95 % CI 0.63 - 0.72 , P=0.021 ) , and the occurrence of major complications was lower for CF versus NCF procedures ( 2.1 % vs. 7.8 % , P=0.010 ) . CONCLUSIONS CF-guided catheter ablation is superior to NCF with regard to procedural safety and avoidance of cardiac perforation . This difference is due to a reduction of cardiac perforation and major complications in the AF subgroup 
    Output:
    