Atorvastatin Using as a Possible Prophylaxis of Postoperative Atrial Fibrillation After Cardiac Surgery

Inclusion Criteria: 1. Men and women over 18 year-old. 2. In sinus rhythm. 3. Affected by valve disease, isolated or associated with coronary artery disease, satisfying requirements for heart surgery under extracorporeal circulation. 4. Women of childbearing potential must use effective contraception and they must commit to maintain it throughout the study. Exclusion Criteria: 1. Urgent surgery. 2. Surgery due to endocarditis. 3. Patients with previous episodes of atrial fibrillation, although they are in sinus rhythm at hospital admission. 4. Treatment with beta-blockers at time of randomization 5. Severe left ventricular dysfunction with ventricular ejection fraction under 30%. 6. Chronic using of NSAIDs and / or corticosteroids at time of randomization 7. Uncontrolled thyroid disease. 8. Active liver disease and / or history of previous chronic liver disease. 9. Alcoholism. 10. Predisposing factors to statins adverse effects: * Increased transaminase levels at baseline (x3 normal value). * Renal failure (creatinine levels over 2 mg/dl). * Previous diagnosis of myopathy of any etiology. 11. Known hypersensitivity to calcium atorvastatin and / or lactose monohydrate 12. In women of childbearing age, positive pregnancy test the day of inclusion in the study. 13. Not signed informed consent. 14. Inability to understand objectives of the study. Exclusion criteria of the study once started: * Withdrawal of patient's consent. * Modification in liver laboratory parameters (transaminases above three times normal value) and / or creatine-fosfokinase level suggesting adverse effects of statins.