Amiodarone + Pacing Avoided Postop Atrial Fib

Major Finding: Atrial fibrillation during hospitalization occurred in 19% of 26 patients on metoprolol, 11% of 35 on amiodarone alone, 9% of 32 on pacing alone, and none of 22 patients on both amiodarone and pacing.

Data Source: A prospective, single-center study of 115 patients randomized to prophylaxis with metoprolol, amiodarone, right atrial pacing, or amiodarone plus right atrial pacing.

Disclosures: Dr. Shea had no relevant financial relationships.

ATLANTA — Combined treatment with amiodarone and prophylactic atrial pacing cut the incidence of postoperative atrial fibrillation to zero in a randomized pilot study with 115 patients undergoing cardiac surgery at one center.

The results also showed metoprolol's relative lack of efficacy: Of patients treated with metoprolol, 19% had new-onset atrial fibrillation, Dr. Jennifer Shea said at the annual meeting of the American College of Cardiology.

“Because the results were promising it made us want to do a larger study,” said Dr. Shea, an internist at George Washington University, Washington.

Surgeons don't agree on the best way to prevent atrial fibrillation, the most common complication following cardiac surgery. Until now, cardiac surgeons at George Washington have used any of the three prophylactic treatments tested in the study: metoprolol, amiodarone, and atrial pacing. The findings suggest that, as a minimum, “maybe metoprolol shouldn't be used,” she said.

The study included patients who were aged 18 or older with sinus rhythm and who were scheduled for coronary artery bypass surgery, isolated valve surgery, or both. After surgery, the patients were randomized to one of four treatments:

▸ Oral metoprolol, starting with a test dose of 25 mg, followed by continued treatment at a level dependent on their heart rate (26 patients). Metoprolol was withheld when the pulse fell below 50 bpm or systolic pressure dropped below 100 mm Hg.

▸ Amiodarone alone, at a dosage of 400 mg oral amiodarone t.i.d for 7 days or until hospital discharge (35 patients). Patients on a beta-blocker prior to surgery continued to receive amiodarone to avoid atrial fibrillation triggered by beta-blocker withdrawal.

▸ Pacing prophylaxis (32 patients). During surgery patients received two epicardial pacing leads on the posterolateral wall of the right atrium. Pacing began on their postoperative arrival to the ICU and continued for 72 hours. The pacing rate was adjusted every 12 hours.

▸ Amiodarone and pacing (22 patients).

The study's primary outcome, the incidence of atrial fibrillation during hospitalization, occurred in 19% of patients on metoprolol, 11% of those on amiodarone alone, 9% of those on pacing alone, and in none of the patients on both amiodarone and pacing. The difference between the combination-therapy group and the metoprolol group was statistically significant. The end point occurred if atrial fibrillation continued for more than an hour, or if it was judged to require treatment.

Length of stay, a secondary outcome, averaged 7 days in the metoprolol patients, 6 days in those on amiodarone, 7.5 days in those paced, and 5.7 days in patients on the combined regimen.

Adverse events constituted another secondary outcome, and included death, myocardial infarction, tachyarrhythmia, bradyarrhythmia, and prolonged intubation. An adverse event occurred in 37% of the metoprolol patients, 16% on amiodarone, 12% managed with pacing, and 27% of those on combined therapy, Dr. Shea said.