***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 —When warfarin is interrupted for surgery , low-molecular-weight heparin is often used as bridging therapy . However , this practice has never been evaluated in a large prospect i ve study . This study was design ed to assess the efficacy and safety of bridging therapy with low-molecular-weight heparin initiated out of hospital . Methods and Results —This was a prospect i ve , multicenter , single-arm cohort study of patients at high risk of arterial embolism ( prosthetic valves and atrial fibrillation with a major risk factor ) .  Warfarin was held for 5 days preoperatively . Low-molecular-weight heparin was given 3 days preoperatively and at least 4 days postoperatively . Patients were followed up for 3 months for thromboembolism and bleeding .  Eleven Canadian tertiary care academic centers participated ; 224 patients were enrolled . Eight patients ( 3.6 % ; 95 % CI , 1.8 to 6.9 ) had an episode of thromboembolism , of which 2 ( 0.9 % ; 95 % CI , 0.2 to 3.2 ) were judged to be due to cardioembolism . Of these 8 episodes of thromboembolism , 6 occurred in patients who had warfarin deferred or withdrawn because of bleeding . There were 15 episodes of major bleeding ( 6.7 % ; 95 % CI , 4.1 to 10.8 ) : 8 occurred intraoperatively or early postoperatively before low-molecular-weight heparin was restarted , 5 occurred in the first postoperative week after low-molecular-weight heparin was restarted , and 2 occurred well after low-molecular-weight heparin was stopped . There were no deaths . Conclusions —Bridging therapy with subcutaneous low-molecular-weight heparin is feasible ; however , the optimal approach for the management of patients who require temporary interruption of warfarin to have invasive procedures is uncertain BACKGROUND Before surgery , most patients receiving oral anticoagulation  require temporary cessation of treatment . Physicians sometimes substitute heparin or low-molecular-weight heparin for oral anticoagulation in the perioperative setting ( " bridging therapy " ) . We sought to characterize rates of bridging therapy use at 9 clinical centers to determine the extent to which the use of bridging is explained by clinical characteristics of patients ( vs physician style ) and to determine the 30-day incidence of thrombotic and bleeding complications . METHODS This was a prospect i ve , multicenter , observational study . Periprocedural bridging anticoagulation was classified as none , prophylactic-dose heparin/low-molecular-weight heparin , or full-dose heparin/low-molecular-weight heparin . We collected data on patient and surgery characteristics , anticoagulation management , and thromboembolic and bleeding events . RESULTS A total of 492 of 497 consecutive patients completed the study ; 54 % , 14 % , and 33 % of patients had no , prophylactic , and full ( therapeutic ) doses , respectively , of heparin/low-molecular-weight heparin postprocedure . Two hospitals treated more than 80 % of their patients with full-dose heparin , whereas the remaining 7 hospitals used full-dose heparin in an average of 22 % of cases ( P<.001 ) ; this variation persisted after adjustment for patient characteristics . There were 4 thromboembolic events ( 0.8 % ) and 16 major bleeding events ( 3.2 % ) . Full-dose heparin/low-molecular-weight heparin postprocedure was associated with a higher likelihood of major bleeding : adjusted odds ratio 4.4 ( 95 % confidence interval , 1.5 - 14.7 ) . CONCLUSION Management of anticoagulation after an invasive procedure varies widely and is not explained by clinical characteristics of patients alone . The risk of major bleeding is strongly associated with the use of postoperative therapeutic doses of heparin/low-molecular-weight heparin OBJECTIVE To estimate the 3-month cumulative incidence of thromboembolism ( TE ) , bleeding , and death among consecutive patients with nonvalvular atrial fibrillation ( AF ) who were receiving long-term anticoagulation therapy and were referred to the Thrombophilia Center at Mayo Clinic for periprocedural anticoagulation management . PATIENTS AND METHODS In a prospect i ve cohort study of consecutive patients receiving long-term anticoagulation therapy who were referred to the Thrombophilia Center for periprocedural anticoagulation management over the 7-year period , January 1 , 1997 , to December 31 , 2003 , 345 patients with nonvalvular AF were eligible for inclusion .  Warfarin was stopped 4 to 5 days before and was restarted after surgery as soon as hemostasis was assured . The decision to provide bridging therapy with heparin was individualized and based on the estimated risks of TE and bleeding . RESULTS The 345 patients with AF ( mean + /- SD age , 74+/-9 years ; 33 % women ) underwent 386 procedures . Warfarin administration was not interrupted for 44 procedures . Periprocedural heparin was provided for 204 procedures . Patients receiving heparin were more likely to have prior TE ( 43 % vs 24 % ; P<.001 ) and a higher CHADS2 ( congestive heart failure , hypertension , age , diabetes , stroke ) score ( 2.2 vs 1.9 ; P=.06 ) . Four patients had 6 episodes of TE ( 3 strokes and 3 acute coronary episodes ; TE rate , 1.1 % ; 95 % confidence interval , 0.0%-2.1 % ) . Nine patients had 10 major bleeding events ( major bleeding rate , 2.7 % ; 95 % confidence interval , 1.0%-4.4 % ) . There were no deaths . Neither bleeding nor TE rates differed by anticoagulant management strategy . CONCLUSION The 3-month cumulative incidence of TE and bleeding among patients with AF in whom anticoagulation was temporarily interrupted for an invasive procedure was low and was not significantly influenced by bridging therapy PURPOSE C and i date s for prostatectomy who require chronic anticoagulant therapy  present a major perioperative management problem due to the threat of significant hemorrhage associated with surgery and the risk of thromboembolism associated with discontinuation of the anticoagulants . We evaluated prospect ively a perioperative routine using low molecular weight heparin substitution to allow safe discontinuation of prophylactic oral anticoagulants in patients undergoing transurethral resection of the prostate . MATERIAL S AND METHODS We treated 20 patients on chronic oral anticoagulant therapy who required prostatectomy for bladder outlet obstruction according to a prospect i ve protocol based on exchange of the oral anticoagulants with perioperative injections of low molecular weight heparin and resumption of oral anticoagulants early postoperatively . The safety and efficacy of this regimen were assessed in comparison to a control group comprised of 20 r and omly selected nonwarfarin treated patients who underwent prostatectomy  during the same period . RESULTS The need for blood transfusions and mean number of units transfused did not significantly differ between the 2 groups . Due to persistent hematuria routine removal of the catheter was possible only in 9 of 20 patients ( 45 % ) in the heparin group compared to 18 of 20 ( 90 % ) in the control group . Average catheterization and hospitalization period in the heparin group was 3.2 days and 4.2 days respectively , compared to 2.1 and 2.1 days in the control group , respectively ( p < 0.01 ) . No long-term hemorrhagic or thromboembolic complications were noted at 3 months postoperatively . CONCLUSIONS Despite longer hospitalization in the heparin treated group , our substitution protocol is safe and effective Background and aims Among patients on long-term anticoagulant therapy who undergo laparoscopic cholecystectomy ( LC ) , bleeding complications have not been extensively investigated . The objective of this study was therefore to investigate postoperative bleeding complications prospect ively in patients on chronic oral anticoagulation . Material s and methods In the period of January 2002 to December 2007 , 44 patients on long-term anticoagulation with warfarin , an oral anticoagulant ( OAC ) , underwent LC in our center .  Oral anticoagulant was discontinued 5 days before the planned date of surgery , and patients were admitted to the hospital 3 days before . Upon admission , bridging anticoagulation with enoxaparin , a low molecular weight heparin ( LMWH ) , was started . When their international normalized ratio ( INR ) decreased to < 1.5 , patients underwent LC . In the absence of postoperative bleeding complications , OAC and LMWH were resumed on the evening of the day of surgery , and LMWH was continued until each patient ’s target INR was reached . A comparison group was comprised by 1,421 consecutively enrolled patients with no comorbid disease who underwent LC during the same period . Results In the comparison group , postoperative bleeding was encountered in 21 patients ( 1.5 % ) . In the anticoagulation group , postoperative bleeding was encountered in 11 patients ( 25 % ) and ranged from minor oozing from a port incision in one patient to hemorrhage , sepsis , and fatality in one patient . In the anticoagulation group , no significant differences were found between patients with and without postoperative bleeding in terms of age , gender , body mass index , American Society of Anesthesiologists score , INR , or other hemostasis parameters . Conclusions In patients who underwent LC with bridging anticoagulation , postoperative bleeding was markedly more frequent than expected and was not predicted by the usual coagulation parameters . This suggests a need for methods that can indicate which patients on long-term anticoagulation are at risk for postoperative bleeding PURPOSE To evaluate postoperative bleeding and thromboembolic complications during dental extraction s in anticoagulated patients , using 2 different protocol s. PATIENTS AND METHODS In total , 214 anticoagulated patients in need of simple dental extraction s were r and omized into 2 groups . Group A consisted of 109 patients on continuous oral anticoagulation therapy ( OAT ) , with a mean international normalized ratio ( INR ) of 2.45 + /- 0.54 . Local hemostasis in these patients was achieved with resorbable collagen sponges , without wound suturing . Group B consisted of 105 patients on bridging therapy with low-molecular-weight heparin ( nadroparin-calcium ) , with a mean INR of 1.26 + /- 0.11 on the day of the procedure . Neither local hemostatic agents nor suturing of the wound was used in these patients . RESULTS Eight ( 7.34 % ) patients in group A and 5 ( 4.76 % ) patients in group B manifested post extraction al bleeding , without statistical significance ( chi(2 ) , Yates ' = 0.253 , P > .05 ) . All cases of hemorrhage were mild and easily controlled using local hemostatic measures . None of the participants in either group experienced thromboembolic complications . CONCLUSIONS In patients receiving OAT with an INR < or=4.0 , simple dental extraction s can be performed safely without interruption or modification of OAT , using local hemostatic measures . Suturing of the wound should be reserved for cases with a greater extent of surgical trauma , and when primary hemostasis 
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CONCLUSIONS Vitamin K antagonist-treated patients receiving periprocedural heparin bridging appear to be at increased risk of overall and major bleeding and at similar risk of thromboembolic events compared to nonbridged patients .