Medication reduces risk of heart irregularities after cardiac surgery

December 27, 2005

Use of the medication amiodarone is associated with one-half the incidence of atrial tachyarrhythmias (rapid, abnormal heart beat) following cardiac surgery, according to a study in the December 28 issue of JAMA.

Atrial tachyarrhythmias, usually atrial fibrillation or atrial flutter, often occur immediately after cardiac surgery and are the most common postoperative complication, according to background information in the article. The incidence of sustained atrial tachyarrhythmias after coronary artery bypass graft (CABG) surgery is approximately 30 percent; after valve surgery, approximately 40 percent; and after combined CABG and valve replacement/repair surgery, approximately 50 percent. The consequences of these atrial tachyarrhythmias include discomfort or anxiety, stroke, exposure to the risks of tachyarrhythmia treatments, prolongation of hospital stay, and increased health care costs. Atrial tachyarrhythmias have recently been reported to increase hospital stay after cardiac surgery by an average of 1.4 days at an additional cost of $6,356 per patient. Substantial effort has been invested in finding an effective, safe, and widely applicable preventive treatment for atrial tachyarrhythmia occurring after cardiac surgery. Previous trials of amiodarone were relatively small and yielded conflicting results.

L. Brent Mitchell, M.D., and colleagues from the University of Calgary, Canada, conducted the Prophylactic Amiodarone for the Prevention of Arrhythmias that Begin Early After Revascularization, Valve Replacement, or Repair (PAPABEAR) trial to test the hypothesis that amiodarone is an effective, well-tolerated, and safe therapy for prevention of atrial tachyarrhythmias after cardiac surgery. The placebo-controlled, randomized trial compared younger patients (less than 65 years) with older patients (65 years or older), patients undergoing CABG surgery compared with patients undergoing cardiac valve surgery or combined CABG and valve replacement/repair surgery, and patients who received preoperative beta-blocker therapy with those who did not.

The study included 601 patients who had CABG surgery and/or valve replacement/repair surgery between February 1, 1999, and September 26, 2003. The patients were followed up for 1 year. Patients received oral amiodarone or placebo, administered 6 days prior to surgery through 6 days after surgery (total of 13 days).

Amiodarone was associated with a halving of the overall incidence of atrial tachyarrhythmias lasting 5 minutes or longer.

Postoperative sustained ventricular tachyarrhythmias occurred less frequently in amiodarone patients (1/299; 0.3 percent) than in placebo patients (8/302; 2.6 percent). There were no differences in serious postoperative complications, in-hospital mortality, or readmission to the hospital within 6 months of discharge or in 1-year mortality.

"The number needed to treat [with amiodarone] to prevent 1 patient from developing postoperative atrial tachyarrhythmia was only 7.5 overall and was even lower in older patients, in patients having valve surgery, and in patients not receiving concomitant beta-blocker therapy," the authors write.

"The PAPABEAR trial demonstrates that a 13-day perioperative course of oral amiodarone is an effective, possibly safe, well-tolerated, and widely applicable therapy for the prevention of postoperative atrial tachyarrhythmia after cardiac surgery. This benefit was associated with a reduction in the probability of perioperative sustained ventricular tachyarrhythmia and a trend toward a reduction in postoperative hospital stay," the researchers conclude.

(JAMA.2005; 294:3093-3100. Available pre-embargo to the media at www.jamamedia.org)
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Editor's Note: For funding/support and financial disclosure information, please see the JAMA article.

Editorial: Prophylaxis Against Postoperative Atrial Fibrillation - Current Progress and Future Directions

In an accompanying editorial, Mihai V. Podgoreanu, M.D., and Joseph P. Mathew, M.D., of Duke University Medical Center, Durham, N.C., comment on the study by Mitchell and colleagues.

"Future study of atrial fibrillation prophylaxis should consider three important methodological issues. First, when addressing the relationship between postoperative atrial fibrillation and complications, it is essential to capture the precise time of onset of both atrial fibrillation and the complications, thus allowing for a detailed examination of the temporal relationship between the two. Second, patients experiencing multiple episodes of atrial fibrillation should be targeted for therapeutic intervention because the incidence of complications is much greater in these patients than in those experiencing a single episode. Amiodarone therapy has potential benefit in this setting as well, having been associated with a lower risk of recurrence in an observational trial. Third, a majority of the known risk factors for postoperative atrial fibrillation should be recorded and accounted for in statistical analyses. The use of a risk index offers statistical advantages and may be used to define patient selection criteria or identify patients for whom prophylactic therapy might be most effective."

"In the meantime, to help prevent postoperative atrial fibrillation, more widespread use of amiodarone for patients undergoing elective cardiac surgery should be considered."

(JAMA.2005; 294:3140-3142. Available pre-embargo to the media at www.jamamedia.org)

The JAMA Network Journals

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