Elsevier

The Lancet

Volume 357, Issue 9259, 17 March 2001, Pages 830-836
The Lancet

Articles
Oral amiodarone for prevention of atrial fibrillation after open heart surgery, the Atrial Fibrillation Suppression Trial (AFIST): a randomised placebo-controlled trial

https://doi.org/10.1016/S0140-6736(00)04196-9Get rights and content

Summary

Background

β-blockers and amiodarone reduce the frequency of atrial fibrillation after open-heart surgery but the effectiveness of oral amiodarone in older patients already receiving β-blockers is unknown. We have assessed the efficacy of oral amiodarone in preventing atrial fibrillation in patients aged 60 years or older undergoing open-heart surgery.

Methods

We did a randomised, double-blind placebocontrolled trial in which patients undergoing open-heart surgery (n=220, average age 73 years) received amiodarone (n=120) or placebo (n=100). Patients enrolled less than 5 days before surgery received 6 g of amiodarone or placebo over 6 days beginning on preoperative day 1. Patients enrolled at least 5 days before surgery received 7 g over 10 days beginning on preoperative day 5.

Findings

Patients on amiodarone had a lower frequency of any atrial fibrillation (22·5% vs 38·0%; p=0·01; absolute difference 15·5% [95% CI 3·4–27·6%]), and there were significant differences in favour of the active drug for symptomatic atrial fibrillation (4·2% vs 18·0%, p=0·001), cerebrovascular accident (1·7% vs 7·0%, p=0·04), and postoperative ventricular tachycardia (1·7% vs 7·0%, p=0·04). β-blocker use (87·5% amiodarone vs 91·0% placebo), nausea (26·7% vs 16·0%), 30-day mortality (3·3% vs 4·0%), symptomatic bradycardia (7·5% vs 7·0%), and hypotension (14·2% vs 10·0%) were similar.

Interpretation

Oral amiodarone prophylaxis in combination with β-blockers prevents atrial fibrillation and symptomatic fibrillation and reduces the risk of cerebrovascular accidents and ventricular tachycardia.

Introduction

Postoperative atrial fibrillation occurs in 27–40% of open-heart surgery patients and could precipitate hypotension, heart failure, ventricular arrhythmias, the need for a pacemaker, and a three-fold increase in the risk of stroke or transient ischaemic attack.1, 2, 3, 4, 5 Age has been identified as the most powerful contributing risk factor for postoperative atrial fibrillation.1, 2, 3, 6, 7 Currently, 56% of the 598 000 coronary bypass (CABG) operations done yearly in the USA are in people aged 65 years or older (www.americanheart.org/Heart_and_Stroke_A_Z_Guide/openh.html accessed on Feb 7, 2001). Postoperatively, there is a significant increase in sympathetic tone, in those who subsequently develop atrial fibrillation.8 This could explain the efficacy of β-blockers in preventing postoperative fibrillation.9, 10

Amiodarone, a class III antiarrhythmic drug with antiadrenergic properties,11, 12 reduces the rate of atrial fibrillation in selected populations.13, 14, 15, 16, 17 Results from previous oral amiodarone trials, although encouraging, leave many issues unsettled. Possible limitations include a limited use of β-blockers and no data about the degree of β-blockade; and one study used an impractical 13 day preoperative loading regimen.13, 14 In addition, these studies were done in populations with a mean age of less than 65 years.13, 14 We aimed to assess efficacy and safety of a brief oral amiodarone regimen in prevention of atrial fibrillation in patients 60 years and older already receiving β-blockers as a part of a critical pathway. The Atrial Fibrillation Suppression Trial (AFIST) study was a randomised, double blind, placebo-controlled trial at a single tertiary care centre in 220 patients undergoing open heart surgery including CABG, valve surgery, or both.

Section snippets

Patients

This study was approved by the Human Subjects Institutional Review Board of Hartford Hospital, a 600-bed tertiary care centre, and patients gave written informed consent. Between February, 1998, and April, 1999, patients undergoing left-heart catheterisation and coronary angiography due to progressive angina pectoris or symptoms of valve disease, and being considered for elective heart surgery were screened (figure 1). To be included, patients needed to be at least 60 years of age,

Results

Baseline characteristics were similar except for the higher percentage of patients with a previous myocardial infarction in the amiodarone group (p=0·005; table 1). Surgical characteristics were similar except fewer patients in the amiodarone group required defibrillation to restore sinus rhythm after aortic cross-clamp release (p=0·04) and the pump heart rate of the precardiopulmonary bypass and postcardiopulmonary bypass were significantly lower (p<0·001 for both; table 2).

The overall risk of

Discussion

We have shown that oral amiodarone prophylaxis reduced the rate of atrial fibrillation in elderly patients undergoing open-heart surgery and receiving concomitant β-blockers. There was also a significant reduction in cerebrovascular accidents with this treatment. However, our mean age was 8–15 years older (as specified below) than in previous studies and the mean left ventricular ejection fraction was fairly low.13, 14, 15, 16, 17 Age above 65 years and left ventricular dysfunction were

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