***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 
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    Input: AIMS To analyse the safety and impact on maintenance of sinus rhythm of transoesophageal echocardiographically guided early cardioversion associated with short-term anticoagulation in a large series of patients with atrial fibrillation and atrial flutter . METHODS AND RESULTS Patients who were c and i date s for cardioversion were eligible for inclusion if they had atrial fibrillation or atrial flutter lasting longer than 2 days or of unknown duration . Patients received short-term anticoagulation with warfarin or heparin and underwent transthoracic echocardiography followed by transoesophageal echocardiography . Early cardioversion was performed if no thrombus was seen on the transoesophageal study . Warfarin was maintained for 1 month after cardioversion . In patients with atrial thrombi , cardioversion was deferred and prolonged anticoagulation was prescribed . The study population included 183 patients . One hundred and sixty nine patients without atrial thrombi underwent early cardioversion . Fourteen patients with atrial thrombi ( 7.6 % ) underwent a second transoesophageal echocardiogram after a median of 4 weeks of oral warfarin , and cardioversion was performed if clot regression was documented . No patient in our study population had a clinical thromboembolic event at 1 month follow-up ( 95 % C.I. 0 - 0.016 ) . The immediate success rate of cardioversion was better among patients with atrial fibrillation < 4 weeks duration compared with patients with atrial fibrillation of longer or of unknown duration : 96.6 % vs 85 % , respectively ( P = 0.014 ) . At 1 month follow-up , the percentage of arrhythmia relapses in patients with initially successful cardioversion was similar in the two groups ( 29 % vs 26 % , P = ns ) ; thus the initial better outcome in patients with recent-onset arrhythmia was not lost . CONCLUSION Transoesophageal echocardiography-guided early cardioversion in concert with short-term anticoagulation is safe . This approach permits abbreviation of the overall duration of atrial fibrillation and has a better impact on the maintenance of sinus rhythm for patients in whom the duration of atrial fibrillation is < 4 weeks BACKGROUND Patients with atrial fibrillation ( AF ) and atrial thrombi have an increased risk for cerebral embolism . However , there is little knowledge about the long-term fate of atrial thrombi and the incidence of cerebral embolism in patients under oral anticoagulation . METHODS Consecutive patients with persistent or permanent AF and left atrial ( LA ) thrombi were included in the study . We performed serial and prospect i ve transesophageal echocardiography , cranial magnetic resonance imaging , and clinical examinations during a period of 3 years . Oral anticoagulation was continued or initiated in all patients . A target INR of 2.5 was intended in all patients . RESULTS Forty-three patients with LA thrombi and persistent or permanent AF were included . During the follow-up period 31(72 % ) of the thrombi disappeared . Patients with disappearance of thrombi had significantly smaller thrombi ( P < 0.01 ) , a lower echogenicity of thrombi ( P < 0.01 ) , and a lower LA volume ( P = 0.02 ) . Twenty-two ( 51 % ) patients suffered from cerebral embolism and /or death during the observation period . Five patients died due to embolic events . The only independent predictors of cerebral embolism were an elevated peak emptying velocity of the LA appendage ( P < 0.001 ) and a history of previous thromboembolism ( P < 0.01 ) . CONCLUSIONS Patients with persistent or permanent AF and atrial thrombi have a high long-term risk of cerebral embolism and /or death ( 51 % ) even despite the oral anticoagulation therapy . Thrombus size may predict thrombus resolution under continued anticoagulation Background —In patients with atrial fibrillation ( AF ) , most thrombus forms in the left atrial appendage ( LAA ) . However , the relation of LAA morphology with LAA thrombus is unknown . Methods and Results —We prospect ively enrolled 633 consecutive patients who were c and i date s for catheter ablation for symptomatic drug-resistant AF .  Transesophageal echocardiography ( TEE ) was performed to assess LAA thrombus . LAA structure was assessed by 3-dimensional TEE . LAA orifice area , depth , volume , and number of lobes were measured on reconstructed 3-dimensional images . Clinical characteristics and echocardiographic measures were compared to determine variables predicting LAA thrombus . Excluded were 69 ( 10.9 % ) patients who met the exclusion criteria . Finally , this study comprised 564 patients , of whom LAA thrombus was observed in 36 ( 6.4 % ) patients . Multivariate analysis revealed CHADS2 ( Congestive heart failure , Hypertension Age>75 , Diabetes mellitus and prior Stroke or transient ischemic attack ) score ( P=0.002 ) , left ventricular ejection fraction ( P=0.01 ) , degree of spontaneous echo contrast ( P=0.02 ) , left atrial volume ( P=0.02 ) , and number of LAA lobes ( P<0.001 ) to be independently associated with thrombus formation . Most patients with LAA thrombus ( 32/34 , 94.4 % ) had ≥3 LAA lobes , whereas LAA thrombus was observed in only 2 ( 0.7 % ) of 296 patients with 1 or 2 lobes . LAA volume significantly decreased in patients maintaining sinus rhythm after catheter ablation ( P=0.0009 ) . Number of LAA lobes did not change in any patient . Conclusions —Complex LAA morphology characterized by an increased number of LAA lobes was associated with the presence of LAA thrombus independently of clinical risk and blood stasis . This study suggests that LAA morphology might be a congenital risk factor for LAA thrombus formation in patients with AF BACKGROUND Because atrial thrombi are poorly detected by conventional noninvasive techniques such as transthoracic echocardiography , patients with prolonged atrial fibrillation usually receive several weeks of oral anticoagulation therapy before cardioversion is attempted . We wondered whether transesophageal echocardiography , an accurate method of detecting atrial thrombi , would allow early cardioversion to be performed safely if no thrombi were identified . METHODS A total of 669 consecutive patients admitted with the diagnosis of atrial fibrillation were screened . Patients were excluded if they were receiving long-term anticoagulation , if the duration of atrial fibrillation was two days or less , if they were not c and i date s for cardioversion , or if transesophageal echocardiography was contraindicated . Of 119 qualifying patients , 94 agreed to participate ; the average duration of atrial fibrillation was 4.5 weeks . Participating patients underwent transthoracic echocardiography and transesophageal echocardiography followed by cardioversion if no thrombi were seen . Short-term anticoagulation with heparin was used in 80 patients before cardioversion , and 60 patients received warfarin for one month after cardioversion . RESULTS Fourteen atrial thrombi were identified in 12 patients ( 13 percent ) , and 12 of the 14 thrombi were visualized only on transesophageal echocardiography . Cardioversion was deferred in all 12 patients . Two of these 12 patients died suddenly ; 4 of the 10 surviving patients underwent uneventful cardioversion after prolonged oral anticoagulation . Seventy-eight of the 82 patients without thrombi underwent successful cardioversion to sinus rhythm ( 47 by means of antiarrhythmic drugs and 31 by electrical cardioversion ) , all without long-term oral anticoagulation . None of these patients ( 95 percent confidence interval , 0 to 4.6 percent ) had an embolic event . CONCLUSIONS In patients with atrial fibrillation of unknown or prolonged duration who are not receiving long-term anticoagulation , atrial thrombi are detected by transesophageal echocardiography in only a small minority ( 13 percent in our study ) . Our preliminary data suggest that if transesophageal echocardiography excludes the presence of thrombi , early cardioversion can be performed safely without the need for prolonged oral anticoagulation before the procedure Background Dabigatran etexilate , a direct thrombin inhibitor and non-vitamin K antagonist oral anticoagulant ( NOAC ) , has been shown to effectively prevent thromboembolic events in patients with non-valvular atrial fibrillation ( AF ) . However , there is a paucity of data on the antithrombotic efficacy and safety of dabigatran in the resolution of left atrial appendage ( LAA ) thrombi in AF patients . Objective The primary objective of the RE-LATED AF trial is to assess whether dabigatran results in a faster complete LAA thrombus resolution as compared to vitamin K antagonist phenprocoumon . Secondary objectives are to assess the impact of dabigatran on complete LAA thrombus resolution rate within 6 weeks of treatment and change in LAA thrombus volume under treatment . Furthermore , this study aims to assess and compare safety and tolerability of dabigatran vs. phenprocoumon . Methods The study is design ed as a prospect i ve , r and omized , open-label , controlled , explorative , blinded endpoint ( PROBE ) trial . Patients with AF and left atrial appendage thrombus confirmed by transoesophageal echocardiography ( TEE ) will be r and omized to receive either dabigatran ( 150 mg bid ) or phenprocoumon ( INR 2–3 ) for the resolution of LAA thrombus formation for at least 21 days . Thrombus resolution will be determined by TEE 3 weeks after treatment initiation and subsequently at weeks 4 and 6 , if the LAA thrombus has not been resolved before . A total of 110 patients are planned to be r and omized . Conclusion This is the first prospect i ve , multicentre , r and omized controlled clinical trial investigating safety and efficacy of a NOAC for the resolution of LAA thrombi in patients with non-valvular AF BACKGROUND Current guidelines recommend unfractionated heparin ( UFH ) or low-molecular-weight heparin plus an oral anticoagulant for the prevention of thromboembolism in patients undergoing electric cardioversion of atrial fibrillation ( AF ) . Selective factor Xa inhibitors , such as fondaparinux , which has a favourable benefit-risk profile in the prevention and treatment of venous thromboembolism and the management of acute coronary syndromes , have not been systematic ally evaluated in this setting . AIM To evaluate the efficacy and safety of fondaparinux versus st and ard treatment in patients undergoing echocardiographically-guided cardioversion of AF . METHODS In this multicentre , r and omized , open-label , controlled , two-parallel-group , phase II pilot study , patients with AF undergoing electric cardioversion following transoesophageal echocardiography ( TEE ) were r and omized to fondaparinux or st and ard therapy ( UFH plus vitamin K antagonist [ VKA ] ) . Patients showing an atrial thrombus in the first TEE ( clot-positive ) were r and omized to treatment with fondaparinux or st and ard care for 4 weeks before cardioversion . RESULTS The primary endpoint ( combined rate of cerebral neurological events , systemic thromboembolism , all-cause death and major bleeding events ) occurred in 3 of 174 ( 1.7 % ) patients on fondaparinux and 2 of 170 ( 1.2 % ) patients on UFH+VKA . The rate of thrombus disappearance among clot-positive patients was higher in the fondaparinux arm ( 11 of 14 ; 78.6 % ) than in the UFH+VKA arm ( 7 of 14 ; 50.0 % ) . Incidences of adverse events were similar ( 45.4 % with fondaparinux and 46.5 % with UFH+VKA ) . CONCLUSION In this pilot study in patients with TEE-guided cardioversion , the use of fondaparinux appeared to be well tolerated , with similar efficacy to UFH+VKA . Furthermore , a trend to greater thrombus resolution was observed PURPOSE Patients ( pts . ) with atrial fibrillation ( AF ) and atrial thrombi are known to have an increased risk for cerebral embolism . However , little is known about the clinical course of atrial thrombi and the incidence of cerebral embolism in those patients during anticoagulation therapy . The high sensitivity of MR imaging ( MRI ) including diffusion-weighted imaging ( DWI ) suggests that this technique could provide an improved estimate of cerebral embolism associated with the presence of left atrial thrombi . The aims of this prospect i ve study were to evaluate 1 ) the prevalence of clinical ly silent and apparent cerebral embolism in pts . with newly diagnosed AF and atrial thrombi using MRI/DWI , 2 ) the long-term fate of atrial thrombi under continues anticoagulation therapy and 3 ) the incidence of cerebral embolism during a follow-up period of 12 months with continuous anticoagulation therapy . MATERIAL S AND METHODS The study group consisted of 32 pts . with 1 ) newly diagnosed 
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CONCLUSIONS Warfarin is the most studied initial OAC agent for treating LAT in nonrheumatic AF and /or AFL with a resolution rate of nearly 80 % .