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Anticoagulation for Atrial Fibrillation after Resolution of Dengue Haemorrhagic Fever.

Dear Sir, 
 
In a recent publication, Pahadiya et al., presented a young patient with atrial fibrillation (AF) during dengue haemorrhagic fever, suggesting the role of acute viral myocarditis [1]. In this interesting case report, the patient was admitted after five days of dengue symptoms. The cardiac arrhythmia was observed in the 3rd day of hospital admission and persisted until the 8th day, two days after the initiation of steroid therapy with dexamethasone. No specific antiarrhythmic therapy was prescribed. The patient was discharged on 12th day, clinically stable, afebrile and with normal haematological laboratory parameters. Unfortunately, despite of the excellent hospital upshot of this patient, the authors did not present his long-term follow-up neither they contemplated the anticoagulation therapy after hospital discharge, late after resolution of the acute phase. 
 
AF is associated with the occurrence of thromboembolic complications, mainly stroke, that are preventable with anticoagulation therapy. The risk of thromboembolism for patients undergoing cardioversion of AF may reach 5% [2]. Pooled data from 32 studies of cardioversion of AF or atrial flutter suggest that 98% of clinical thromboembolic events occur within 10 days after restoration of sinus rhythm [3]. Thus, current guidelines for the management of patients with AF [4] are emphatic in recommending oral anticoagulation for at least 4 weeks after conversion of an episode of 48 hours’ duration or longer, regardless of the CHA2DS2-VASc score for thromboembolism. 
 
During the acute phase of haemorragic dengue fever, there is no statement regarding the management of anticoagulation in patients with indication for this therapy, but it seems reasonable the avoidance of any antithrombotic drugs in these days. However, after a good resolution of the acute phase of the infection, those patients must be considered for anticoagulation if their arrhythmia had lasted for more than 48 hours. 
 
In our first report of the association of AF with haemorrhagic dengue fever, the patient had the sinus rhythm restored in 24 hours with amiodarone infusion [5]. He did not receive oral anticoagulation due to the short duration of AF. 
 
In the case of Pahadiya et al., the episode of atrial fibrillation lasted for 5 days [1]. The decision for anticoagulation in this patient is difficult. However, I do believe that this therapy should have been initiated. 
 
Finally, I would like to state that, in our first report of atrial fibrillation due to dengue haemorrhagic fever [5], we had not mentioned some role for steroid therapy, as it was referred in the discussion of Pahadiya et al., [1].