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 — Data regarding the long-term efficacy of atrial fibrillation ( AF ) ablation are still lacking . Methods and Results —Two hundred four consecutive patients symptomatic for paroxysmal or persistent/permanent AF were r and omly assigned to 2 different ablation schemes : pulmonary vein isolation ( PVI ) and PVI plus left linear lesions ( LL ) . Primary end point was to assess the maintenance of sinus rhythm ( SR ) after procedures 1 and 2 in the absence of antiarrhythmic drugs in a long-term follow-up of at least 3 years . Paroxysmal AF — With a single procedure at 12-month follow-up , 46 % of patients treated with PVI maintained SR , whereas at 3-year follow-up , 29 % were in SR ; using the “ PVI plus LL ” at the 12-month follow-up , 57 % of patients were in SR , whereas at the 3-year follow-up , 53 % remained in SR . After a second procedure , the long-term overall success rate without antiarrhythmic drugs was 62 % with PVI and 85 % with PVI plus LL . Persistent/Permanent AF — With a single procedure at the 12-month follow-up , 27 % of patients treated with PVI were in SR , whereas at the 3-year follow-up , 19 % maintained SR ; using the PVI plus LL with a single procedure at the 12-month follow-up 45 % of patients were in SR , whereas at the 3-year follow-up , 41 % remained in SR . After a second procedure , the long-term overall success rate without antiarrhythmic drugs was 39 % with PVI and 75 % with PVI plus LL . Conclusions —A long-term follow-up of AF ablation shows that short-term results can not be considered permanent because AF recurrences are still present after the first year especially in patients who have had “ PVI ” strategy .  PVI isolation plus LL is superior to the PVI strategy in maintaining SR without antiarrhythmic drugs after procedures 1 and 2 both in paroxysmal and persistent AF AIMS To investigate the effectiveness of additional substrate modification ( SM ) by left atrial ( LA ) linear lesions as compared with pulmonary vein isolation ( PVI ) alone in patients with persistent atrial fibrillation ( AF ) in a prospect i ve r and omized study . Percutaneous PVI has evolved as an accepted treatment for paroxysmal AF but seemed to be less effective in patients with persistent AF . The benefit of PVI alone and additional linear lesions has not been vali date d in a r and omized study so far . METHODS AND RESULTS Sixty-two patients with persistent AF ( median duration 7 , range 1 - 18 months ) were r and omly assigned to either PVI alone ( n = 30 ) or additional SM ( n = 32 ) consisting of a roof line connecting both left superior and right superior PV and LA isthmus ablation between left inferior PV and mitral annulus . Procedures including SM were performed using a three-dimensional mapping system ( EnSite NavX , St Jude Medical , St Paul , MN , USA ) . Anti-arrhythmic drugs were discontinued within 8 weeks after ablation in both groups . Follow-up included daily trans-telephonic ECG transmitted irrespective of the patient 's symptoms . PVI was successful in 98 % of all targeted veins in both groups . Additional SM did not increase fluoroscopy time ( 72.1+/-18.7 vs. 72.9+/-17.3 min , P=0.92 ) because of the use of three-dimensional navigation in the PVI+SM group . AF recurrences within the first 4 weeks following ablation were more common after PVI alone ( 77 % ) than additional SM ( 44 % , P=0.002 ) . After a follow-up time of 487 ( 429 - 570 ) days , only 20 % of patients undergoing st and alone PVI  remained in sinus rhythm when compared with 69 % following PVI combined with SM ( P=0.0001 ) . Two patients assigned to PVI+SM experienced procedure-related complications ( cardiac tamponade and minor stroke ) which resolved without sequelae . CONCLUSION PVI alone is insufficient in the treatment of persistent AF . However , additional left linear lesions increase the success rate significantly . Early AF-relapses are associated with a negative outcome after PVI alone but not following additional SM BACKGROUND Different catheter ablation ( CA ) strategies have been established in the treatment of persistent atrial fibrillation ( persAF ) .  Pulmonary vein isolation ( PVI ) only might be an option for the initial ablation procedure . There is a paucity of outcome data on second-generation cryoballoon ( CBG2 ) PVI in persAF . METHODS Patients with symptomatic drug-refractory persAF who underwent initial CA of AF  were prospect ively enrolled and PVI was performed with CBG2 . The primary composite endpoint was freedom from AF , atrial tachycardia , or related symptoms after a 3-month blanking period . The secondary endpoint referred to periprocedural complications . RESULTS One hundred seventy-three consecutive patients ( 64±10 years , 29 % female ) with symptomatic drug-refractory persAF were identified . Acute PVI was achieved in 100 % of pulmonary veins with the CB technique . The left atrial procedure time was 112±30min . Major complications occurred in 1.7 % ( 3 of 173 patients ) including two phrenic nerve palsies ( 1 % ) , which resolved until discharge , and one pericardial effusion ( 0.6 % ) . Follow-up ≥12 months was completed for 157 of 173 patients ( 91 % ) . Median follow-up was 14 months . At 12 months , the primary composite endpoint was achieved in 129 of 157 patients ( 82 % ) . However , 22 of 129 patients at risk ( 17 % ) were still on antiarrhythmic drugs . A relapse during the blanking period was identified as the only independent predictor for AF recurrence . CONCLUSION PVI using the second-generation cryoballoon is a reasonable treatment option for patients with symptomatic drug-refractory persAF with a favorable rate of freedom from AF and a low complication rate BACKGROUND Focal impulse and rotor modulation ( FIRM ) was based on the premise that atrial fibrillation ( AF ) is sustained by rotors that are sufficiently stable to be eliminated by targeted ablation . Early experience reported high success as compared to conventional strategies . OBJECTIVE The purpose of this study was to report on a single-center experience with extended follow-up by using FIRM in a variety of patients with AF . METHODS All FIRM-guided ablation procedures were included . During spontaneous or induced AF , FIRM software constructed phase maps to identify putative AF sources , then targeted for radiofrequency ablation , with adjunctive pulmonary vein isolation ( PVI ) , if needed . All mapped rotors and /or sources were eliminated on the basis of repeated FIRM mapping . RESULTS Of 47 patients , sustained AF was not present or induced in 4 patients who did not undergo FIRM ablation . Of the remaining 43 patients , prior AF was paroxysmal in 9 ( 21 % ) and 72 % had a median of 1 prior PVI . Spontaneous AF ( n = 22 , 52 % ) and induced AF ( n = 21 , 49 % ) were mapped , and all patients had rotors identified ( 1.8 ± 0.8 per patient ; 70 % in the left atrium ) . AF termination occurred in 2 patients ( 5 % ) and none organized to atrial tachycardia . Touch-up redo PVI was also performed in 31 patients ( 72 % ) . At 16.0 ± 10.7 months ( range 1 - 34 months ) , only 9 patients ( 21 % ) were free of recurrent AF ; and only 5 patients ( 12 % ) were free of AF and off antiarrhythmic drugs . CONCLUSION Long-term clinical results after FIRM ablation in this diverse challenging cohort showed poor efficacy . R and omized clinical trials are needed to evaluate the efficacy and clinical utility of the FIRM ablation approach for treating AF AIMS Irrigated multi-electrode ablation ( IMEA ) is a novel tool to perform pulmonary vein isolation ( PVI ) . The aim was to compare IMEA with point-by-point radiofrequency ( RF ) ablation in patients with persistent atrial fibrillation ( AF ) undergoing PVI . METHODS AND RESULTS Forty-nine patients ( age 60 ± 9 years , 82 % male ) were studied . In 24 patients , the IMEA catheter was used in conjunction with an electroanatomic mapping system . Twenty-five patients undergoing RF point-by-point ablation ( RF-PVI ) served as a control group . Validation of PVI based on the IMEA catheter was performed using a st and ard circular mapping catheter . Ninety-two of 94 pulmonary veins ( PVs ) ( 98 % ) were isolated using IMEA alone . Procedure time was 125 ± 23 min in the IMEA group and 127 ± 31 min in the RF-PVI group ( P = 0.79 ) . Fluoroscopy time was 12.2 ( 11 - 16.1 ) min with IMEA compared with 5.2 ( 4.1 - 9.3 ) min in the RF-PVI group ( P < 0.001 ) . Net ablation time was 11.8 ( 10.2 - 15.4 ) min in the IMEA group compared with 33.6 ( 30.3 - 40.1 ) min in the RF-PVI group ( P < 0.001 ) . Of 94 PVs presumed to be isolated after IMEA ablation , validation using a st and ard circular mapping catheter showed persistent PV potentials in 33 PVs ( 35 % ) , requiring additional IMEA ablation . At 12 months , 16 of 24 patients ( 67 % ) in the IMEA group compared with 17 of 25 patients ( 68 % ) in RF-PVI group were free from AF ( P > 0.99 ) . CONCLUSION With similar total procedure duration , IMEA-PVI was associated with shorter net ablation time and longer fluoroscopy time . Irrigated multi-electrode ablation recordings were not sufficient to confirm isolation in 35 % of PVs . Single-procedure efficacy after 12 months was similar between the two groups BACKGROUND Long-term success rates using ablation for persistent atrial fibrillation ( AF ) are disappointing and usually do not exceed 60 % . OBJECTIVES This study sought to compare arrhythmia-free survival between pulmonary vein isolation ( PVI ) and a stepwise approach ( full defrag ) consisting of PVI , ablation of complex fractionated electrograms , and additional linear ablation lines in the setting of atrial tachycardias ( AT ) in patients with persistent AF after PVI . METHODS From November 2010 to February 2013 , 205 patients ( 151 men ; 61.7 ± 10.2 years of age ) underwent de novo ablation for persistent AF . Subsequently , patients were prospect ively r and omized to either PVI alone ( n = 78 ) or full defrag ( n = 75 ) , with 52 patients not r and omized due to AF termination with the original PVI . The primary endpoint was recurrence of any AT after a blanking period of 3 months . RESULTS During the entire study , 241 ablations were performed ( mean : 1.59 in the PVI-alone group , 1.55 in the full-defrag group ) . With the stepwise approach , termination of AF occurred in 45 ( 60 % ) patients . However , arrhythmia-free survival did not differ whether patients underwent single or multiple procedures ( p = 0.468 ) . Procedure duration , fluoroscopy time , and radiofrequency duration were significantly longer in the full-defrag group ( all p < 0.001 ) . CONCLUSIONS A stepwise approach aim ed at AF termination does not seem to provide additional benefit over PVI alone in patients with persistent AF , but it is associated with significantly longer procedural and fluoroscopic duration as well as radiofrequency application time . ( The R and omized Catheter Ablation of Persist End Atrial Fibrillation Study [ CHASE-AF ] ; NCT01580124 ) AIMS To assess the 1 year efficacy of pulmonary vein isolation ( PVI ) as index procedure for persistent atrial fibrillation ( PersAF ) comparing conventional radiofrequency irrigated-tip catheter ablation ( RFCA ) using contact-force technology and ablation using the second-generation cryoballoon ( CB-AdvA ) . METHODS AND RESULTS One hundred consecutive patients ( 74 male , 74 % ; mean age 62.4 ± 9.6 years ) with drug-refractory PersAF undergoing PVI using RFCA and CB-AdvA were enrolled . Follow-up was based on outpatient clinic visits including Holter-electrocardiograms . Recurrence of atrial tachyarrhythmias ( ATas ) was defined as a symptomatic or documented episode > 30 s. Among 100 patients , 50 underwent RFCA whereas 50 CB-AdvA.  Mean procedure and fluoroscopy times were 90.5 ± 41.7 vs. 140.2 ± 46.9 min and 14.5 ± 6.6 vs. 19.8 ± 6.8 min in the CB-Adv and in the RFCA group , respectively ( P < 0.0 
    Output:
    
agent
A PVI-only strategy in PeAF patients with a low prevalence of structural heart disease using contemporary technology yields excellent outcomes comparable to those for paroxysmal AF ablation
***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 — Data regarding the long-term efficacy of atrial fibrillation ( AF ) ablation are still lacking . Methods and Results —Two hundred four consecutive patients symptomatic for paroxysmal or persistent/permanent AF were r and omly assigned to 2 different ablation schemes : pulmonary vein isolation ( PVI ) and PVI plus left linear lesions ( LL ) . Primary end point was to assess the maintenance of sinus rhythm ( SR ) after procedures 1 and 2 in the absence of antiarrhythmic drugs in a long-term follow-up of at least 3 years . Paroxysmal AF — With a single procedure at 12-month follow-up , 46 % of patients treated with PVI maintained SR , whereas at 3-year follow-up , 29 % were in SR ; using the “ PVI plus LL ” at the 12-month follow-up , 57 % of patients were in SR , whereas at the 3-year follow-up , 53 % remained in SR . After a second procedure , the long-term overall success rate without antiarrhythmic drugs was 62 % with PVI and 85 % with PVI plus LL . Persistent/Permanent AF — With a single procedure at the 12-month follow-up , 27 % of patients treated with PVI were in SR , whereas at the 3-year follow-up , 19 % maintained SR ; using the PVI plus LL with a single procedure at the 12-month follow-up 45 % of patients were in SR , whereas at the 3-year follow-up , 41 % remained in SR . After a second procedure , the long-term overall success rate without antiarrhythmic drugs was 39 % with PVI and 75 % with PVI plus LL . Conclusions —A long-term follow-up of AF ablation shows that short-term results can not be considered permanent because AF recurrences are still present after the first year especially in patients who have had “ PVI ” strategy .  PVI isolation plus LL is superior to the PVI strategy in maintaining SR without antiarrhythmic drugs after procedures 1 and 2 both in paroxysmal and persistent AF AIMS To investigate the effectiveness of additional substrate modification ( SM ) by left atrial ( LA ) linear lesions as compared with pulmonary vein isolation ( PVI ) alone in patients with persistent atrial fibrillation ( AF ) in a prospect i ve r and omized study . Percutaneous PVI has evolved as an accepted treatment for paroxysmal AF but seemed to be less effective in patients with persistent AF . The benefit of PVI alone and additional linear lesions has not been vali date d in a r and omized study so far . METHODS AND RESULTS Sixty-two patients with persistent AF ( median duration 7 , range 1 - 18 months ) were r and omly assigned to either PVI alone ( n = 30 ) or additional SM ( n = 32 ) consisting of a roof line connecting both left superior and right superior PV and LA isthmus ablation between left inferior PV and mitral annulus . Procedures including SM were performed using a three-dimensional mapping system ( EnSite NavX , St Jude Medical , St Paul , MN , USA ) . Anti-arrhythmic drugs were discontinued within 8 weeks after ablation in both groups . Follow-up included daily trans-telephonic ECG transmitted irrespective of the patient 's symptoms . PVI was successful in 98 % of all targeted veins in both groups . Additional SM did not increase fluoroscopy time ( 72.1+/-18.7 vs. 72.9+/-17.3 min , P=0.92 ) because of the use of three-dimensional navigation in the PVI+SM group . AF recurrences within the first 4 weeks following ablation were more common after PVI alone ( 77 % ) than additional SM ( 44 % , P=0.002 ) . After a follow-up time of 487 ( 429 - 570 ) days , only 20 % of patients undergoing st and alone PVI  remained in sinus rhythm when compared with 69 % following PVI combined with SM ( P=0.0001 ) . Two patients assigned to PVI+SM experienced procedure-related complications ( cardiac tamponade and minor stroke ) which resolved without sequelae . CONCLUSION PVI alone is insufficient in the treatment of persistent AF . However , additional left linear lesions increase the success rate significantly . Early AF-relapses are associated with a negative outcome after PVI alone but not following additional SM BACKGROUND Different catheter ablation ( CA ) strategies have been established in the treatment of persistent atrial fibrillation ( persAF ) .  Pulmonary vein isolation ( PVI ) only might be an option for the initial ablation procedure . There is a paucity of outcome data on second-generation cryoballoon ( CBG2 ) PVI in persAF . METHODS Patients with symptomatic drug-refractory persAF who underwent initial CA of AF  were prospect ively enrolled and PVI was performed with CBG2 . The primary composite endpoint was freedom from AF , atrial tachycardia , or related symptoms after a 3-month blanking period . The secondary endpoint referred to periprocedural complications . RESULTS One hundred seventy-three consecutive patients ( 64±10 years , 29 % female ) with symptomatic drug-refractory persAF were identified . Acute PVI was achieved in 100 % of pulmonary veins with the CB technique . The left atrial procedure time was 112±30min . Major complications occurred in 1.7 % ( 3 of 173 patients ) including two phrenic nerve palsies ( 1 % ) , which resolved until discharge , and one pericardial effusion ( 0.6 % ) . Follow-up ≥12 months was completed for 157 of 173 patients ( 91 % ) . Median follow-up was 14 months . At 12 months , the primary composite endpoint was achieved in 129 of 157 patients ( 82 % ) . However , 22 of 129 patients at risk ( 17 % ) were still on antiarrhythmic drugs . A relapse during the blanking period was identified as the only independent predictor for AF recurrence . CONCLUSION PVI using the second-generation cryoballoon is a reasonable treatment option for patients with symptomatic drug-refractory persAF with a favorable rate of freedom from AF and a low complication rate BACKGROUND Focal impulse and rotor modulation ( FIRM ) was based on the premise that atrial fibrillation ( AF ) is sustained by rotors that are sufficiently stable to be eliminated by targeted ablation . Early experience reported high success as compared to conventional strategies . OBJECTIVE The purpose of this study was to report on a single-center experience with extended follow-up by using FIRM in a variety of patients with AF . METHODS All FIRM-guided ablation procedures were included . During spontaneous or induced AF , FIRM software constructed phase maps to identify putative AF sources , then targeted for radiofrequency ablation , with adjunctive pulmonary vein isolation ( PVI ) , if needed . All mapped rotors and /or sources were eliminated on the basis of repeated FIRM mapping . RESULTS Of 47 patients , sustained AF was not present or induced in 4 patients who did not undergo FIRM ablation . Of the remaining 43 patients , prior AF was paroxysmal in 9 ( 21 % ) and 72 % had a median of 1 prior PVI . Spontaneous AF ( n = 22 , 52 % ) and induced AF ( n = 21 , 49 % ) were mapped , and all patients had rotors identified ( 1.8 ± 0.8 per patient ; 70 % in the left atrium ) . AF termination occurred in 2 patients ( 5 % ) and none organized to atrial tachycardia . Touch-up redo PVI was also performed in 31 patients ( 72 % ) . At 16.0 ± 10.7 months ( range 1 - 34 months ) , only 9 patients ( 21 % ) were free of recurrent AF ; and only 5 patients ( 12 % ) were free of AF and off antiarrhythmic drugs . CONCLUSION Long-term clinical results after FIRM ablation in this diverse challenging cohort showed poor efficacy . R and omized clinical trials are needed to evaluate the efficacy and clinical utility of the FIRM ablation approach for treating AF AIMS Irrigated multi-electrode ablation ( IMEA ) is a novel tool to perform pulmonary vein isolation ( PVI ) . The aim was to compare IMEA with point-by-point radiofrequency ( RF ) ablation in patients with persistent atrial fibrillation ( AF ) undergoing PVI . METHODS AND RESULTS Forty-nine patients ( age 60 ± 9 years , 82 % male ) were studied . In 24 patients , the IMEA catheter was used in conjunction with an electroanatomic mapping system . Twenty-five patients undergoing RF point-by-point ablation ( RF-PVI ) served as a control group . Validation of PVI based on the IMEA catheter was performed using a st and ard circular mapping catheter . Ninety-two of 94 pulmonary veins ( PVs ) ( 98 % ) were isolated using IMEA alone . Procedure time was 125 ± 23 min in the IMEA group and 127 ± 31 min in the RF-PVI group ( P = 0.79 ) . Fluoroscopy time was 12.2 ( 11 - 16.1 ) min with IMEA compared with 5.2 ( 4.1 - 9.3 ) min in the RF-PVI group ( P < 0.001 ) . Net ablation time was 11.8 ( 10.2 - 15.4 ) min in the IMEA group compared with 33.6 ( 30.3 - 40.1 ) min in the RF-PVI group ( P < 0.001 ) . Of 94 PVs presumed to be isolated after IMEA ablation , validation using a st and ard circular mapping catheter showed persistent PV potentials in 33 PVs ( 35 % ) , requiring additional IMEA ablation . At 12 months , 16 of 24 patients ( 67 % ) in the IMEA group compared with 17 of 25 patients ( 68 % ) in RF-PVI group were free from AF ( P > 0.99 ) . CONCLUSION With similar total procedure duration , IMEA-PVI was associated with shorter net ablation time and longer fluoroscopy time . Irrigated multi-electrode ablation recordings were not sufficient to confirm isolation in 35 % of PVs . Single-procedure efficacy after 12 months was similar between the two groups BACKGROUND Long-term success rates using ablation for persistent atrial fibrillation ( AF ) are disappointing and usually do not exceed 60 % . OBJECTIVES This study sought to compare arrhythmia-free survival between pulmonary vein isolation ( PVI ) and a stepwise approach ( full defrag ) consisting of PVI , ablation of complex fractionated electrograms , and additional linear ablation lines in the setting of atrial tachycardias ( AT ) in patients with persistent AF after PVI . METHODS From November 2010 to February 2013 , 205 patients ( 151 men ; 61.7 ± 10.2 years of age ) underwent de novo ablation for persistent AF . Subsequently , patients were prospect ively r and omized to either PVI alone ( n = 78 ) or full defrag ( n = 75 ) , with 52 patients not r and omized due to AF termination with the original PVI . The primary endpoint was recurrence of any AT after a blanking period of 3 months . RESULTS During the entire study , 241 ablations were performed ( mean : 1.59 in the PVI-alone group , 1.55 in the full-defrag group ) . With the stepwise approach , termination of AF occurred in 45 ( 60 % ) patients . However , arrhythmia-free survival did not differ whether patients underwent single or multiple procedures ( p = 0.468 ) . Procedure duration , fluoroscopy time , and radiofrequency duration were significantly longer in the full-defrag group ( all p < 0.001 ) . CONCLUSIONS A stepwise approach aim ed at AF termination does not seem to provide additional benefit over PVI alone in patients with persistent AF , but it is associated with significantly longer procedural and fluoroscopic duration as well as radiofrequency application time . ( The R and omized Catheter Ablation of Persist End Atrial Fibrillation Study [ CHASE-AF ] ; NCT01580124 ) AIMS To assess the 1 year efficacy of pulmonary vein isolation ( PVI ) as index procedure for persistent atrial fibrillation ( PersAF ) comparing conventional radiofrequency irrigated-tip catheter ablation ( RFCA ) using contact-force technology and ablation using the second-generation cryoballoon ( CB-AdvA ) . METHODS AND RESULTS One hundred consecutive patients ( 74 male , 74 % ; mean age 62.4 ± 9.6 years ) with drug-refractory PersAF undergoing PVI using RFCA and CB-AdvA were enrolled . Follow-up was based on outpatient clinic visits including Holter-electrocardiograms . Recurrence of atrial tachyarrhythmias ( ATas ) was defined as a symptomatic or documented episode > 30 s. Among 100 patients , 50 underwent RFCA whereas 50 CB-AdvA.  Mean procedure and fluoroscopy times were 90.5 ± 41.7 vs. 140.2 ± 46.9 min and 14.5 ± 6.6 vs. 19.8 ± 6.8 min in the CB-Adv and in the RFCA group , respectively ( P < 0.0 
    Output:
    