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(Circulation. 2006;114:I-1 – I-4.)
© 2006 American Heart Association, Inc.

Arrhythmia Surgery

Intravenous Administration of Metoprolol Is More Effective Than Oral Administration in the Prevention of Atrial Fibrillation After Cardiac Surgery

Jari Halonen, MD; Tapio Hakala, MD, PhD; Tommi Auvinen, MD; Jari Karjalainen, MD, PhD; Anu Turpeinen, MD, PhD; Ari Uusaro, MD, PhD; Pirjo Halonen, PhD; Juha Hartikainen, MD, PhD; Mikko Hippeläinen, MD, PhD

From the Departments of Surgery (J.H., T.H., T.A., J.K., M.H.), Anaesthesiology and Intensive Care (A.U.), and Medicine (A.T., J.H.) of Kuopio University Hospital, and the IT Service Centre (P.H.) of Kuopio University, Kuopio, Finland.

Correspondence to Jari Halonen, Department of Surgery, Kuopio University Hospital, PO Box 1777, FIN-70211 Kuopio, Finland. E-mail jari.halonen{at}kuh.fi

Background— Atrial fibrillation (AF) is the most common arrhythmia to occur after cardiac surgery, with an incidence of 20% to 40%. AF is associated with postoperative complications, including increased risk of stroke and need of additional treatment, as well as prolonged hospital stay and increased costs. It has been shown that prophylactic oral administration of ß-blocker therapy reduces the incidence of postoperative AF after cardiac surgery. However, it is possible that absorption of drugs is impaired after cardiopulmonary perfusion associated with cardiac surgery. The purpose of this prospective, controlled, randomized trial was to study compare intravenous and per oral metoprolol administration in the prevention of AF after cardiac surgery.

Methods and Results— 240 consecutive patients who were scheduled to undergo their first on-pump coronary artery bypass graft (CABG), aortic valve replacement, or combined aortic valve replacement and CABG were randomized to receive 48-hour infusion of metoprolol or oral metoprolol starting on the first postoperative morning. Patients were excluded if they had contraindications for ß-blocker or had to stay >1 day in the intensive care unit. Dosage of metoprolol was adjusted according to heart rate. The dosage was 1 to 3 mg/h in the intravenous group and from 25 mg twice per day to 50 mg 3 times per day in the oral group. The incidence of postoperative AF was significantly lower in the intravenous group than in the oral group (16.8% versus 28.1%, P=0.036). No serious adverse effects were associated with intravenous metoprolol therapy.

Conclusions— Our study suggests that intravenous metoprolol is well-tolerated and more effective than oral metoprolol in the prevention of AF after cardiac surgery.

Key Words: atrial fibrillation • beta adrenergic receptors antagonists • cardiac surgery • prevention