Post-operative Corticosteroid Treatment After Mitral Valve Surgery

Inclusion Criteria: * open mitral valve surgery * patients agrees to participate in the study * adult (minimum 18 years of age) Exclusion Criteria: * atrial fibrillation onset before first postoperative morning * prolonged intensive care unit stay (patient needs to stay in intensive care unit after first postoperative day) * patient is underaged, does not want to participate or can not make the decision by himself or herself because of ie memory disability * diabetes mellitus requiring insulin treatment and with recent hypo- or hyperglycemias which required hospital treatment * systemic mucous infections * known allergy or oversensitivity to hydrocortisone * Cushing syndrome * history of psychosis * history of ulcus or active ulcus * chronic atrial fibrillation or atrial flutter * corticosteroid or immunosuppressive treatment in use for any reason * active tuberculosis infection * severe renal impairment (serum creatinine 200 umol/l or over) * history of deep or superficial venous trombosis * Herpes simplex -ceratitis