AF rates after heart surgery similar with metoprolol, amiodarone prophylaxis
MedWire News: Intravenous (IV) metoprolol produces similar rates of atrial fibrillation (AF) after cardiac surgery as amiodarone, Finnish researchers suggest.
However, Jari Halonen (Kuopio University Hospital) and colleagues say their findings do not definitively prove that "the two treatments are equally effective in preventing AF after cardiac surgery."
They highlight that their study design lacked sufficient power to demonstrate equality due to widely ranging confidence intervals (CI).
In the study, the researchers recruited 316 Finnish patients who were hemodynamically stable and free of AF 24 hours after cardiac surgery. All patients were randomly allocated to receive IV metoprolol 1-3 mg/h (n=159) or amiodarone 15 mg/kg of body weight, daily (to a maximum dose of 1000 mg; n=157), at 15-21 hours postsurgery.
The findings, published in the Annals of Internal Medicine, show that in the 48 hours after surgery, AF occurred at similar rates of 23.9% and 24.8% among patients taking metoprolol and amiodarone, respectively.
This finding however, was nonsignificant, with a wide CI ranging from -8.9 to 7.0 percentage points.
This CI however, does not correspond with the specified 5 percentage-point margin required to prove equivalence, say the researchers.
Of note, time to AF onset differed between both groups, with AF occurring after a mean 21 and 27 hours among patients who received metoprolol and amiodarone, respectively (p=0.02).
Halonen et al say: "We cannot exclude the possibility that true differences in efficacy exist between amiodarone and beta-blockers in the prevention of AF."
They conclude: "Larger multicenter trials or meta-analyses are needed to confirm the equality of metoprolol and amiodarone in preventing postoperative AF."
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By Lauretta Ihonor