EPLERAF-Study: Eplerenone in the Prevention of Atrial Fibrillation Recurrences After Cardioversion

Inclusion Criteria: * Persistent atrial fibrillation (AF), AF persistence for \> 7 days but \< 1 year * Total AF history \< 2 years * Written informed consent of the patient * Age ≥18 years * Female patients are sterilised or postmenopausal or apply an adequate method for contraception (Pearl index \<1%) and have a negative pregnancy test (ß-HCG) and do not breastfeed/nurse. Exclusion Criteria: * Hemodynamic instability or symptoms not allowing cardioversion to be delayed for 3 weeks * Myocardial infarction within the last 3 months * Heart failure NYHA class III - IV * Uncontrolled hypertension, defined as a systolic blood pressure \> 160 mm Hg and/or a diastolic blood pressure \> 95 mm Hg (anti-hypertensive treatment is allowed). * Pre-treatment with an aldosterone antagonist or other potassium sparing diuretics * Instable angina pectoris * Use of Digitalis * Use of class I or class III antiarrhythmic drugs (must be stopped at least 5 half-life before) * Contraindication or hypersensitivity to ß-blockers * Open heart surgery within the last 3 months * Pregnancy * Acute and reversible illnesses * Acute and chronic infection * Alcohol or drug abuse or a severe progressive extracardiac disease * Untreated manifest and latent hyper- or hypothyroidism or \< 3 months peripheral euthyroidism (normal fT3) * Moderate to severe renal insufficiency (Creatinine clearance less than 50 ml/min) * Patients with liver cirrhosis (Child-Pugh class C) * Co-administration of strong CYP3A4 inhibitors (e.g. Itraconazole, Ketoconazole, Ritonavir, Nelfinavir, Clarithromycin, Telithromycin and Nephazodon) * Hypersensitivity against Eplerenone and/or one of the other components of the tablet (see Fachinformation) * Serum potassium \> 5 mmol/l * Patients unlikely to comply with the protocol