Early Versus Late DC-cardioversion of Persistent Atrial Fibrillation. Effect on Atrial Remodeling,Inflammatory and Neurohumoral Markers and Recurrence of Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia present in 1% of population under 60 years of age and reaching up to 15% at 80 years. AF is associated with reduced quality of life, increased morbidity, mortality and health economic costs. Presentation of AF differs substantially among patients ranging from self-limiting short episodes (paroxysmal AF), longstanding episodes (persistent AF) where direct current (DC) cardioversion is needed, to chronic atrial fibrillation. Treatment of AF is individually tailored in accordance to symptoms, type of AF and thromboembolic risk. The standard treatment of symptomatic persistent AF is DC-cardioversion preceded by anticoagulant treatment with Warfarin. According to guidelines DC-cardioversion can be performed when anticoagulation treatment has been in therapeutic range for at least 4 weeks. However introduction of Pradaxa (Dabigatran) has enabled an earlier DC cardioversion, reducing time to cardioversion to a 3 week period. During anticoagulation treatment persistence of AF contributes to left atrial remodeling and increases in inflammatory and neurohumoral biomarkers. The prolonged duration of AF and the remodeling of the left atrium increase the risk of AF recurrence after DC-cardioversion. Early cardioversion of patients with persistent AF is possible if preceded by transesophageal echocardiography (TEE). The TEE guided DC- cardioversion, as demonstrated in the ACUTE study, is a safe and efficient alternative to conventional treatment. This treatment regime is not routinely used in clinical practice. The aim of this study is to compare early DC-cardioversion (within 72 hours) to conventional treatment (Pradaxa prior to DC-cardioversion). 140 patients with persistent AF will be randomized to early cardioversion preceded by TEE in accordance with guidelines or conventional treatment with Pradaxa for 4 weeks prior to DC-cardioversion. The investigators will determine the outcome in the two groups regarding: * Lef