Rapid heart rhythms originating from the upper heart chambers (atrial tachyarrhythmias) are very common after open-heart surgery. The hypothesis of the PAPABEAR study is that a brief (13 day) peri-operative course of oral amiodarone therapy would be effective and safe for the prevention of these post-operative atrial tachyarrhythmias.

Six hundred and one patients who were about to undergo non-emergent open-heart surgery were randomized to receive oral amiodarone (10 mg/kg/day) or its matching placebo from six days before surgery through 6 days after surgery. The major outcome tracked was the incidence of more than 5 minutes of an atrial tachyarrhythmia that prompted therapy by the sixth post-operative day. Safety was assessed by the incidence of dosage reduction of blinded therapy, non-fatal post-operative complications, and in-hospital mortality. The randomization scheme was stratified to permit separate analysis of patients less than versus more than or equal to 65 years of age, patients having coronary artery bypass surgery alone versus those having valve surgery with or without concomitant bypass surgery, and patients also receiving versus not also receiving concomitant therapy with a beta-blocker medication.

Inclusion Criteria:

• non-emergent coronary artery bypass surgery or valve replacement or repair
• informed consent

Exclusion Criteria:

• any heart rhythm other than sinus
• myocardial infarction within two weeks
• Class IV congestive Heart Failure
• requirement for antiarrhythmic drug therapy
• history of sustained atrial tachyarrhythmias
• treatment with amiodarone within 3 months
• sinus bradycardia (less than 50 bpm) while awake
• advanced conduction system disease
• prolonged QT interval
• clinical hypo- or hyperthyroidism
• women of child bearing potential