***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 — 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 — Periprocedural thromboembolic and hemorrhagic events are worrisome complications of catheter ablation for atrial fibrillation ( AF ) . The periprocedural anticoagulation management could play a role in the incidence of these complications . Although ablation procedures performed without warfarin discontinuation seem to be associated with lower thromboembolic risk , no r and omized study exists . Methods and Results — This was a prospect i ve , open-label , r and omized , parallel-group , multicenter study assessing the role of continuous warfarin therapy in preventing periprocedural thromboembolic and hemorrhagic events after radiofrequency catheter ablation . Patients with CHADS2 score ≥1 were included . Patients were r and omly assigned in a 1:1 ratio to the off-warfarin or on-warfarin arm . The incidence of thromboembolic events in the 48 hours after ablation was the primary end point of the study . The study enrolled 1584 patients : 790 assigned to discontinue warfarin ( group 1 ) and 794 assigned to continuous warfarin ( group 2 ) . No statistical difference in baseline characteristics was observed . There were 39 thromboembolic events ( 3.7 % strokes [ n=29 ] and 1.3 % transient ischemic attacks [ n=10 ] ) in group 1 : two events ( 0.87 % ) in patients with paroxysmal AF , 4 ( 2.3 % ) in patients with persistent AF , and 33 ( 8.5 % ) in patients with long-st and ing persistent AF . Only 2 strokes ( 0.25 % ) in patients with long-st and ing persistent AF were observed in group 2 ( P<0.001 ) . Warfarin discontinuation emerged as a strong predictor of periprocedural thromboembolism ( odds ratio , 13 ; 95 % confidence interval , 3.1–55.6 ; P<0.001 ) . Conclusion — This is the first r and omized study showing that performing catheter ablation of AF without warfarin discontinuation reduces the occurrence of periprocedural stroke and minor bleeding complications compared with bridging with low-molecular-weight heparin . Clinical Trial Registration — URL : http://www . clinical trials.gov . Unique identifier : NCT01006876 Background : The novel oral anticoagulants ( NOACs ) are used for stroke prevention in atrial fibrillation ( AF ) , but their safety and efficacy in the periablation period are not well established . Additionally , no st and ard procedure for managing periprocedural and intraprocedural anticoagulation has been established . Objective : To evaluate the frequency of hemorrhagic and thrombotic events as well as periprocedural management strategies of NOACs compared with warfarin as anticoagulation therapy for AF ablation . Methods : This was a retrospective cohort study from a prospect i ve AF ablation registry maintained at a large , academic medical center . Results : A total of 374 cases ( 173 warfarin , 123 dabigatran , 61 rivaroxaban , and 17 apixaban ) were included in the analysis . The overall hemorrhagic/thrombotic event rate was 14.2 % ( major hemorrhage 2.7 % , minor hemorrhage 11.2 % , thrombotic stroke 0.5 % ) . The frequency of minor hemorrhage was significantly higher with warfarin compared with dabigatran ( 15 % vs 5.7 % , P = 0.012 ) . The average heparin dose required to reach the goal activated clotting time ( ACT ) was 5600 units for warfarin , 12 900 units for dabigatran ( P < 0.001 ) , 15 100 units for rivaroxaban ( P < 0.001 ) , and 14 700 units for apixaban ( P < 0.001 ) . The average time in minutes to reach the goal ACT was significantly longer , compared with warfarin , for dabigatran ( 57 vs 28 , P < 0.001 ) , rivaroxaban ( 63 vs 28 , P < 0.001 ) , and apixaban ( 72 vs 28 , P < 0.001 ) . Conclusions : Compared with warfarin , periprocedural anticoagulation with dabigatran result ed in fewer minor hemorrhages and total adverse events after AF ablation . Patients anticoagulated with NOACs required larger doses of heparin and took longer to reach the goal ACT compared with patients anticoagulated with warfarin Aims VENTURE-AF is the first prospect i ve r and omized trial of uninterrupted rivaroxaban and vitamin K antagonists ( VKAs ) in patients with non-valvular atrial fibrillation ( NVAF ) undergoing catheter ablation ( CA ) . Methods and results Trial size was administratively set at 250 , the protocol -specified target . Events were independently and blindly adjudicated . We r and omly assigned 248 NVAF patients  to uninterrupted rivaroxaban ( 20 mg once-daily ) or to an uninterrupted VKA prior to CA and for 4 weeks afterwards . The primary endpoint was major bleeding events after CA . Secondary endpoints included thromboembolic events ( composite of stroke , systemic embolism , myocardial infa rct ion , and vascular death ) and other bleeding or procedure-attributable events . Patients were 59.5 ± 10 years of age , 71 % male , 74 % paroxysmal AF , and had a CHA2DS2-VASc score of 1.6 .  The average total heparin dose used to manage activated clotting time ( ACT ) was slightly higher ( 13 871 vs. 10 964 units ; P < 0.001 ) and the mean ACT level attained slightly lower ( 302 vs. 332 s ; P < 0.001 ) in rivaroxaban and VKA arms , respectively . The incidence of major bleeding was low ( 0.4 % ; 1 major bleeding event ) . Similarly , thromboembolic events were low ( 0.8 % ; 1 ischemic stroke and 1 vascular death ) . All events occurred in the VKA arm and all after CA . The number of any adjudicated events ( 26 vs. 25 ) , any bleeding events ( 21 vs. 18 ) , and any other procedure-attributable events ( 5 vs. 5 ) were similar . Conclusion In patients undergoing CA for AF , the use of uninterrupted oral rivaroxaban was feasible and event rates were similar to those for uninterrupted VKA therapy . Name of the Trial Registry Clinical trials.gov trial registration number is NCT01729871 OBJECTIVES The purpose of this study was to evaluate the feasibility and safety of periprocedural dabigatran during atrial fibrillation ( AF ) ablation . BACKGROUND AF ablation requires optimal periprocedural anticoagulation for minimizing bleeding and thromboembolic complications . The safety and efficacy of dabigatran as a periprocedural anticoagulant for AF ablation are unknown . METHODS We performed a multicenter , observational study from a prospect i ve registry including all consecutive patients undergoing AF ablation in 8 high-volume centers in the United States . All patients receiving dabigatran therapy who underwent AF ablation on periprocedural dabigatran , with the dose held on the morning of the procedure , were matched by age , sex , and type of AF with an equal number of patients undergoing AF ablation with uninterrupted warfarin therapy over the same period . RESULTS A total of 290 patients , including 145 taking periprocedural dabigatran and an equal number of matched patients taking uninterrupted periprocedural warfarin , were included in the study . The mean age was 60 years with 79 % being male and 57 % having paroxysmal AF . Both groups had a similar CHADS(2 ) score , left atrial size , and left ventricular ejection fraction . Three thromboembolic complications ( 2.1 % ) occurred in the dabigatran group compared with none in the warfarin group ( p = 0.25 ) . The dabigatran group had a significantly higher major bleeding rate ( 6 % vs. 1 % ; p = 0.019 ) , total bleeding rate ( 14 % vs. 6 % ; p = 0.031 ) , and composite of bleeding and thromboembolic complications ( 16 % vs. 6 % ; p = 0.009 ) compared with the warfarin group . Dabigatran use was confirmed as an independent predictor of bleeding or thromboembolic complications ( odds ratio : 2.76 , 95 % confidence interval : 1.22 to 6.25 ; p = 0.01 ) on multivariate regression analysis . CONCLUSIONS In patients undergoing AF ablation , periprocedural dabigatran use significantly increases the risk of bleeding or thromboembolic complications compared with uninterrupted warfarin therapy BACKGROUND We aim ed to evaluate the feasibility of an oral direct thrombin inhibitor , dabigatran , as a periprocedural anticoagulant for use with ablation of atrial fibrillation ( AF ) . METHODS Consecutive patients scheduled to undergo an AF ablation were r and omly assigned to receive dabigatran ( n = 45 ) or warfarin ( n = 45 ) to compare their clinical feasibility . Both of those oral anticoagulants were discontinued the day before the ablation and were resumed after confirming hemostasis of the venipuncture site . A bridging therapy with heparin was not used in either of the patient groups . RESULTS Dabigatran was switched to warfarin before the ablation because of dyspepsia in three patients . An occurrence of rebleeding from the venipuncture site was less common in dabigatran-allocated patients than in warfarin-allocated patients ( 20 % vs 44 % ; P = 0.013 ) . The reduction in the D-dimer level after the initiation of oral anticoagulants was greater in the dabigatran-allocated patients than in the warfarin-allocated patients . The time from the initiation of the anticoagulants to the ablation was significantly shorter in the dabigatran-allocated patients than in the warfarin-allocated patients ( 43 ± 7 vs 63 ± 13 days ; P < 0.0001 ) . There was only one fatal periprocedural complication in a patient receiving warfarin , who had a mesenteric arterial thrombosis after the ablation . CONCLUSIONS An anticoagulation strategy with dabigatran may surpass that with warfarin in reducing both the periprocedural risk of minor bleeding and a hypercoagulable state , and the time to ablation in patients undergoing ablation of AF BACKGROUND The use of warfarin reduces the rate of ischemic stroke in patients with atrial fibrillation but requires frequent monitoring and dose adjustment . Rivaroxaban , an oral factor Xa inhibitor , may provide more consistent and predictable anticoagulation than warfarin . METHODS In a double-blind trial , we r and omly assigned 14,264 patients with nonvalvular atrial fibrillation who were at increased risk for stroke to receive either rivaroxaban ( at a daily dose of 20 mg ) or dose-adjusted warfarin . The per- protocol , as-treated primary analysis was design ed to determine whether rivaroxaban was noninferior to warfarin for the primary end point of stroke or systemic 
    Output:
    
Use of NOACs compared to VKAs significantly reduced the risk of bleeding in patients with AF ablation .
Similarly , the risk of bleeding was lower with uninterrupted NOACs than with uninterrupted VKAs , and with interrupted NOACs than with interrupted VKAs .