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: OBJECTIVES We sought to test how catheter ablation using an open irrigation catheter ( OIC ) compares with st and ard catheters for pulmonary vein antrum isolation . BACKGROUND Open irrigation catheters have the advantage of delivering greater power without increasing the temperature of the catheter tip , which enables deeper and wider lesions without the formation of coagulum on catheters . METHODS Catheter ablation was performed using an 8-mm catheter ( 8MC ) or an OIC .  Patients were r and omized to 3 groups : 8MC ; OIC-1 , OIC with a higher peak power ( 50 W ) ; and OIC-2 , OIC with lower peak power ( 35 W ) . RESULTS A total of 180 patients were r and omized to the 3 treatment strategies .  Isolation of pulmonary vein antra was achieved in all patients . The freedom from atrial fibrillation was significantly greater in the 8MC and OIC-1 groups compared with the OIC-2 group ( 78 % , 82 % , and 68 % , respectively , p = 0.043 ) . Fluoroscopy time was lower in OIC-1 compared with OIC-2 and 8MC ( 28 + /- 1 min , 53 + /- 2 min , and 46 + /- 2 min , respectively , p = 0.001 ) . The mean left atrium instrumentation time was lower in the OIC-1 compared with the OIC-2 and 8MC groups ( 59 + /- 3 min , 90 + /- 5 min , and 88 + /- 4 min , respectively , p = 0.001 ) . However , there was a greater incidence of " pops " in the OIC-1 ( 100 % , 0 % , 0 % , p < 0.001 ) along with higher incidences of pericardial effusion ( 20 % , 0 % , 0 % , p < 0.001 ) and gastrointestinal complaints ( 17 % in OIC-1 , 3 % in 8MC , and 5 % in OIC-2 , p = 0.031 ) . CONCLUSIONS Although there was a decrease in fluoroscopy and left atrium instrumentation time with the use of OIC at higher power , this setting was associated with increased cardiovascular and gastrointestinal complications Background — The best approach to management of anticoagulation before and after atrial fibrillation ablation is not known . Methods and Results — We compared outcomes in consecutive patients undergoing pulmonary vein antrum isolation for persistent atrial fibrillation . Early in our practice , warfarin was stopped 3 days before ablation , and a transesophageal echocardiogram was performed to rule out clot . Enoxaparin , initially 1 mg/kg twice daily ( group 1 ) and then 0.5 mg/kg twice daily ( group 2 ) , was used to “ bridge ” patients after ablation . Subsequently , warfarin was continued to maintain the international normalized ratio between 2 and 3.5 ( group 3 ) . Minor bleeding was defined as hematoma that did not require intervention . Major bleeding was defined as either cardiac tamponade , hematoma that required intervention , or bleeding that required blood transfusion .  Pulmonary vein ablation was performed in 355 patients ( group 1=105 , group 2=100 , and group 3=150 ) . More patients had spontaneous echocardiographic contrast in groups 1 and 2 . One patient in group 1 had an ischemic stroke compared with 2 patients in group 2 and no patients in group 3 . In group 1 , 23 patients had minor bleeding , 9 had major bleeding , and 1 had pericardial effusion but no tamponade . In group 2 , 19 patients had minor bleeding , and 2 patients developed symptomatic pericardial effusion with need for pericardiocentesis 1 week after discharge . In group 3 , 8 patients developed minor bleeding , and 1 patient developed pericardial effusion with no tamponade . Conclusions — Continuation of warfarin throughout pulmonary vein ablation without administration of enoxaparin is safe and efficacious . This strategy can be an alternative to bridging with enoxaparin or heparin in the periprocedural period Background —This prospect i ve clinical study evaluates the feasibility and efficacy of combined linear mitral isthmus ablation and pulmonary vein ( PV ) isolation in patients with paroxysmal atrial fibrillation ( AF ) . Methods and Results —One hundred consecutive patients ( 13 women ; age 55±10 years ) with drug-refractory , symptomatic paroxysmal AF underwent PV isolation and linear ablation of the cavotricuspid isthmus and the mitral isthmus ( lateral mitral annulus to the left inferior PV ) . They were compared with 100 consecutive patients ( 14 women ; age , 52±10 years ) undergoing PV isolation and cavotricuspid ablation without mitral isthmus ablation .  Bidirectional mitral isthmus block was confirmed by demonstrating ( 1 ) a parallel corridor of double potentials during coronary sinus ( CS ) pacing , ( 2 ) an activation detour by pacing either side of the line , and ( 3 ) differential pacing techniques . Isolation of all PVs and cavotricuspid isthmus ablation were performed successfully in all . Mitral isthmus block was achieved in 92 patients after 20±10 minutes of endocardial radiofrequency application and an additional 5±4 minutes of epicardial radiofrequency application from within the CS in 68 , result ing in a conduction delay of 151±26 ms during CS pacing . Thirty-two patients with mitral isthmus ablation compared with 49 without had recurrent atrial arrhythmia ( P=0.02 ) requiring further ablation . At 1 year after the last procedure , 87 patients with mitral isthmus ablation and 69 without ( P=0.002 ) were arrhythmia free without antiarrhythmic drugs , mitral isthmus ablation being the only factor associated with long-term success ( RR for AF recurrence , 0.2 ; CI , 0.1 to 0.4 ; P<0.001 ) . Conclusions —Catheter ablation of the mitral isthmus results consistently in demonstrable conduction block and is associated with a high cure rate for paroxysmal AF BACKGROUND Recent data have shown that the septum and anterior left atrial ( LA ) wall may contain " rotor " sites required for AF maintenance . However , whether adding ablation of such sites to st and ard ICE-guided PVAI improves outcome is not well known . OBJECTIVE To determine if adjuvant anterior LA ablation during PVAI improves the cure rate of paroxysmal and permanent AF . METHODS One hundred AF patients ( 60 paroxysmal , 40 persistent/permanent ) undergoing first-time PVAI were enrolled over three months to receive adjuvant anterior LA ablation ( Group I ) . These patients were compared with 100 r and omly selected , matched first-time PVAI controls from the preceding three months who did not receive adjuvant ablation ( Group II ) . All 200 patients underwent ICE-guided PVAI during which all four PV antra and SVC were isolated . In group I , a decapolar lasso catheter was used to map the septum and anterior LA wall during AF ( induced or spontaneous ) for continuous high-frequency , fractionated electrograms ( CFAE ) . Sites where CFAE were identified were ablated until the local EGM was eliminated . A complete anterior line of block was not a requisite endpoint . Patients were followed up for 12 months . Recurrence was assessed post-PVAI by symptoms , clinic visits , and Holter at 3 , 6 , and 12 months . Patients also wore rhythm transmitters for the first 3 months . Recurrence was any AF/AFL > 1 min occurring > 2 months post-PVAI . RESULTS Patients ( age 56 + /- 11 years , 37 % female , EF 53%+/- 11 % ) did not differ in baseline characteristics between group I and II by design . Group I patients had longer procedure time ( 188 + /- 45 min vs 162 + /- 37 min ) and RF duration ( 57 + /- 12 min vs 44 + /- 20 min ) than group II ( P < 0.05 for both ) . Overall recurrence occurred in 15/100 ( 15 % ) in group I and 20/100 ( 20 % ) in group II ( P = 0.054 ) . Success rates did not differ for paroxysmal patients between group I and II ( 87 % vs 85 % , respectively ) . However , for persistent/permanent patients , group I had a higher success rate compared with group II ( 82 % vs 72 % , P = 0.047 ) . CONCLUSIONS Adjuvant anterior LA ablation does not appear to impact procedural outcome in patients with paroxysmal AF but may offer benefit to patients with persistent/permanent AF BACKGROUND CartoXP and CartoMerge have been used to treat atrial fibrillation ( AF ) for several years . Our r and omized prospect i ve study compared clinical outcomes of these two versions of three dimensional electroanatomic mapping system in guiding catheter ablation for paroxysmal atrial fibrillation ( PAF ) . METHODS Eighty-one patients with symptomatic , drug refractory PAF were r and omly assigned to  CartoMerge group ( n=42 , mean age ( 54.5+/-13.1 ) years , history of AF=3.2 years ) or CartoXP group ( n=39 , mean age ( 59.8+/-15.6 ) years , history of AF = 2.9 years ) . All patients underwent 64-slice computed tomography ( MSCT ) 1 to 3 days prior to ablation procedure . Using CartoMerge(TM ) Image Integration Module , 3D anatomical images of the left atrium ( LA ) and pulmonary veins ( PVs ) derived from MSCT of CartoMerge group were established and merged with the electroanatomical map . The integrated images were used to guide the procedure of circumferential pulmonary vein isolation ( CPVI ) . In the other group , CPVI was guided just by CartoXP . The endpoint of CPVI in both groups was abolition or dissociation of pulmonary vein potentials ( PVPs ) . RESULTS Mapping points to establish the electroanatomical model of the LA/PVs were 48.7+/-13.4 in CartoMerge group and 62.5+/-15.7 in CartoXP group ( P<0.001 ) . Mean distance between mapping points and the MSCT surfaces in CartoMerge group was ( 1.59+/-0.33 ) mm . Accomplishment of abolition or dissociation of PVPs was achieved 95.2 % in CartoMerge group and 92.3 % in CartoXP group . Duration s of procedure and exposure to X-ray were ( 156+/-25 ) minutes , ( 179+/-21 ) minutes ( P<0.001 ) and ( 19.6+/-7.5 ) minutes , ( 28.5+/-12.8 ) minutes ( P<0.001 ) , respectively . After a follow-up with duration of ( 11.9+/-3.1 ) months vs ( 12.4+/-3.6 ) months post the first ablation procedure , patients free of AF were 33 ( 78.6 % ) in CartoMerge group and 29 ( 74.4 % ) in CartoXP group ( P>0.50 ) . No patient suffered pulmonary vein stenosis , atrioesophageal fistula , stroke or death . CONCLUSION Compared to CartoXP , CartoMerge shortened the catheter ablation procedure and exposure to X-ray , without affecting the clinical outcomes of circumferential pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation in experienced centres 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 
    Output:
    
agent
Contribution This systematic review found that radiofrequency ablation after a failed drug course maintained sinus rhythm more often than continuation of drug therapy alone .
The benefits of maintaining sinus rhythm with antiarrhythmic drugs appeared to be offset by the serious adverse effects of the drugs .
***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: OBJECTIVES We sought to test how catheter ablation using an open irrigation catheter ( OIC ) compares with st and ard catheters for pulmonary vein antrum isolation . BACKGROUND Open irrigation catheters have the advantage of delivering greater power without increasing the temperature of the catheter tip , which enables deeper and wider lesions without the formation of coagulum on catheters . METHODS Catheter ablation was performed using an 8-mm catheter ( 8MC ) or an OIC .  Patients were r and omized to 3 groups : 8MC ; OIC-1 , OIC with a higher peak power ( 50 W ) ; and OIC-2 , OIC with lower peak power ( 35 W ) . RESULTS A total of 180 patients were r and omized to the 3 treatment strategies .  Isolation of pulmonary vein antra was achieved in all patients . The freedom from atrial fibrillation was significantly greater in the 8MC and OIC-1 groups compared with the OIC-2 group ( 78 % , 82 % , and 68 % , respectively , p = 0.043 ) . Fluoroscopy time was lower in OIC-1 compared with OIC-2 and 8MC ( 28 + /- 1 min , 53 + /- 2 min , and 46 + /- 2 min , respectively , p = 0.001 ) . The mean left atrium instrumentation time was lower in the OIC-1 compared with the OIC-2 and 8MC groups ( 59 + /- 3 min , 90 + /- 5 min , and 88 + /- 4 min , respectively , p = 0.001 ) . However , there was a greater incidence of " pops " in the OIC-1 ( 100 % , 0 % , 0 % , p < 0.001 ) along with higher incidences of pericardial effusion ( 20 % , 0 % , 0 % , p < 0.001 ) and gastrointestinal complaints ( 17 % in OIC-1 , 3 % in 8MC , and 5 % in OIC-2 , p = 0.031 ) . CONCLUSIONS Although there was a decrease in fluoroscopy and left atrium instrumentation time with the use of OIC at higher power , this setting was associated with increased cardiovascular and gastrointestinal complications Background — The best approach to management of anticoagulation before and after atrial fibrillation ablation is not known . Methods and Results — We compared outcomes in consecutive patients undergoing pulmonary vein antrum isolation for persistent atrial fibrillation . Early in our practice , warfarin was stopped 3 days before ablation , and a transesophageal echocardiogram was performed to rule out clot . Enoxaparin , initially 1 mg/kg twice daily ( group 1 ) and then 0.5 mg/kg twice daily ( group 2 ) , was used to “ bridge ” patients after ablation . Subsequently , warfarin was continued to maintain the international normalized ratio between 2 and 3.5 ( group 3 ) . Minor bleeding was defined as hematoma that did not require intervention . Major bleeding was defined as either cardiac tamponade , hematoma that required intervention , or bleeding that required blood transfusion .  Pulmonary vein ablation was performed in 355 patients ( group 1=105 , group 2=100 , and group 3=150 ) . More patients had spontaneous echocardiographic contrast in groups 1 and 2 . One patient in group 1 had an ischemic stroke compared with 2 patients in group 2 and no patients in group 3 . In group 1 , 23 patients had minor bleeding , 9 had major bleeding , and 1 had pericardial effusion but no tamponade . In group 2 , 19 patients had minor bleeding , and 2 patients developed symptomatic pericardial effusion with need for pericardiocentesis 1 week after discharge . In group 3 , 8 patients developed minor bleeding , and 1 patient developed pericardial effusion with no tamponade . Conclusions — Continuation of warfarin throughout pulmonary vein ablation without administration of enoxaparin is safe and efficacious . This strategy can be an alternative to bridging with enoxaparin or heparin in the periprocedural period Background —This prospect i ve clinical study evaluates the feasibility and efficacy of combined linear mitral isthmus ablation and pulmonary vein ( PV ) isolation in patients with paroxysmal atrial fibrillation ( AF ) . Methods and Results —One hundred consecutive patients ( 13 women ; age 55±10 years ) with drug-refractory , symptomatic paroxysmal AF underwent PV isolation and linear ablation of the cavotricuspid isthmus and the mitral isthmus ( lateral mitral annulus to the left inferior PV ) . They were compared with 100 consecutive patients ( 14 women ; age , 52±10 years ) undergoing PV isolation and cavotricuspid ablation without mitral isthmus ablation .  Bidirectional mitral isthmus block was confirmed by demonstrating ( 1 ) a parallel corridor of double potentials during coronary sinus ( CS ) pacing , ( 2 ) an activation detour by pacing either side of the line , and ( 3 ) differential pacing techniques . Isolation of all PVs and cavotricuspid isthmus ablation were performed successfully in all . Mitral isthmus block was achieved in 92 patients after 20±10 minutes of endocardial radiofrequency application and an additional 5±4 minutes of epicardial radiofrequency application from within the CS in 68 , result ing in a conduction delay of 151±26 ms during CS pacing . Thirty-two patients with mitral isthmus ablation compared with 49 without had recurrent atrial arrhythmia ( P=0.02 ) requiring further ablation . At 1 year after the last procedure , 87 patients with mitral isthmus ablation and 69 without ( P=0.002 ) were arrhythmia free without antiarrhythmic drugs , mitral isthmus ablation being the only factor associated with long-term success ( RR for AF recurrence , 0.2 ; CI , 0.1 to 0.4 ; P<0.001 ) . Conclusions —Catheter ablation of the mitral isthmus results consistently in demonstrable conduction block and is associated with a high cure rate for paroxysmal AF BACKGROUND Recent data have shown that the septum and anterior left atrial ( LA ) wall may contain " rotor " sites required for AF maintenance . However , whether adding ablation of such sites to st and ard ICE-guided PVAI improves outcome is not well known . OBJECTIVE To determine if adjuvant anterior LA ablation during PVAI improves the cure rate of paroxysmal and permanent AF . METHODS One hundred AF patients ( 60 paroxysmal , 40 persistent/permanent ) undergoing first-time PVAI were enrolled over three months to receive adjuvant anterior LA ablation ( Group I ) . These patients were compared with 100 r and omly selected , matched first-time PVAI controls from the preceding three months who did not receive adjuvant ablation ( Group II ) . All 200 patients underwent ICE-guided PVAI during which all four PV antra and SVC were isolated . In group I , a decapolar lasso catheter was used to map the septum and anterior LA wall during AF ( induced or spontaneous ) for continuous high-frequency , fractionated electrograms ( CFAE ) . Sites where CFAE were identified were ablated until the local EGM was eliminated . A complete anterior line of block was not a requisite endpoint . Patients were followed up for 12 months . Recurrence was assessed post-PVAI by symptoms , clinic visits , and Holter at 3 , 6 , and 12 months . Patients also wore rhythm transmitters for the first 3 months . Recurrence was any AF/AFL > 1 min occurring > 2 months post-PVAI . RESULTS Patients ( age 56 + /- 11 years , 37 % female , EF 53%+/- 11 % ) did not differ in baseline characteristics between group I and II by design . Group I patients had longer procedure time ( 188 + /- 45 min vs 162 + /- 37 min ) and RF duration ( 57 + /- 12 min vs 44 + /- 20 min ) than group II ( P < 0.05 for both ) . Overall recurrence occurred in 15/100 ( 15 % ) in group I and 20/100 ( 20 % ) in group II ( P = 0.054 ) . Success rates did not differ for paroxysmal patients between group I and II ( 87 % vs 85 % , respectively ) . However , for persistent/permanent patients , group I had a higher success rate compared with group II ( 82 % vs 72 % , P = 0.047 ) . CONCLUSIONS Adjuvant anterior LA ablation does not appear to impact procedural outcome in patients with paroxysmal AF but may offer benefit to patients with persistent/permanent AF BACKGROUND CartoXP and CartoMerge have been used to treat atrial fibrillation ( AF ) for several years . Our r and omized prospect i ve study compared clinical outcomes of these two versions of three dimensional electroanatomic mapping system in guiding catheter ablation for paroxysmal atrial fibrillation ( PAF ) . METHODS Eighty-one patients with symptomatic , drug refractory PAF were r and omly assigned to  CartoMerge group ( n=42 , mean age ( 54.5+/-13.1 ) years , history of AF=3.2 years ) or CartoXP group ( n=39 , mean age ( 59.8+/-15.6 ) years , history of AF = 2.9 years ) . All patients underwent 64-slice computed tomography ( MSCT ) 1 to 3 days prior to ablation procedure . Using CartoMerge(TM ) Image Integration Module , 3D anatomical images of the left atrium ( LA ) and pulmonary veins ( PVs ) derived from MSCT of CartoMerge group were established and merged with the electroanatomical map . The integrated images were used to guide the procedure of circumferential pulmonary vein isolation ( CPVI ) . In the other group , CPVI was guided just by CartoXP . The endpoint of CPVI in both groups was abolition or dissociation of pulmonary vein potentials ( PVPs ) . RESULTS Mapping points to establish the electroanatomical model of the LA/PVs were 48.7+/-13.4 in CartoMerge group and 62.5+/-15.7 in CartoXP group ( P<0.001 ) . Mean distance between mapping points and the MSCT surfaces in CartoMerge group was ( 1.59+/-0.33 ) mm . Accomplishment of abolition or dissociation of PVPs was achieved 95.2 % in CartoMerge group and 92.3 % in CartoXP group . Duration s of procedure and exposure to X-ray were ( 156+/-25 ) minutes , ( 179+/-21 ) minutes ( P<0.001 ) and ( 19.6+/-7.5 ) minutes , ( 28.5+/-12.8 ) minutes ( P<0.001 ) , respectively . After a follow-up with duration of ( 11.9+/-3.1 ) months vs ( 12.4+/-3.6 ) months post the first ablation procedure , patients free of AF were 33 ( 78.6 % ) in CartoMerge group and 29 ( 74.4 % ) in CartoXP group ( P>0.50 ) . No patient suffered pulmonary vein stenosis , atrioesophageal fistula , stroke or death . CONCLUSION Compared to CartoXP , CartoMerge shortened the catheter ablation procedure and exposure to X-ray , without affecting the clinical outcomes of circumferential pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation in experienced centres 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 
    Output:
    