Amiodarone

We’re going to focus on rhythm control medications today, in particular amiodarone. Amiodarone is a potent anti-arrhythmic drug that can be take as a tablet or an injectable infusion (in the hospital). It suppresses AF through a combination of different anti-arrhythmic mechanisms. Although several rhythm control drugs exist, your doctor may choose to prescribe amiodarone because:

1. Amiodarone has minimal effect on the heart pumping function, especially important for patients with an associated heart failure.
2. Patients with coronary artery disease are not recommended to take some of the other rhythm control drugs like flecainde whereas amiodarone doesn’t carry the same risk for this group.
3. Studies have shown amiodarone is more effective than other anti-arrhythmic drugs. An elegant Canadian trial compared amiodarone to two other commonly chosen rhythm control drugs; sotalol and propafenone. Out of the 403 enrolled patients with AF, the 50% that were randomised to amiodarone group (35% recurrence rate) had a lower rate of AF recurrence after an average of 16 months follow-up compared to the sotalol/propafenone group (63% recurrence rate).

But (and there’s always a but) this greater efficacy comes at a cost- long-term amiodarone use is associated with side effects for some people. In the above trial, 34% of patients in the amiodarone group stopped taking the drug, most commonly due to side effects. These are often dose and duration dependent; with a 15% rate of side effects in the first year but potentially occurring in up to 50% who take it over the long-term. Most commonly this was gut-related symptoms but in a small number it was due to suspected side effects on the lungs or thyroid organ or liver. Therefore it is important that patients taking this effecting rhythm control medication have regular blood tests to monitor for these. Amiodarone also contains iodine, so should not be taken by anyone who is allergic to iodine or by pregnant women.

It can be used as a short-term AF treatment, until other rhythm control treatments can be put in place e.g. catheter ablation, electrical cardioversion or the reversal of an acute cause like infection or during the recovery after heart surgery. Taking amiodarone is a trade-off of it’s potency to suppress AF versus it’s risk of possible side effects. Many patients tolerate it without issue, especially in the short-term and so it is important that if you are taking it, you are properly counselled of this risk:benefit ratio by your healthcare team.

Roy D, Talajic M, Dorian P, Connolly S, Eisenberg MJ, Green M, Kus T, Lambert J, Dubuc M, Gagné P, Nattel S, Thibault B. Amiodarone to prevent recurrence of atrial fibrillation. Canadian Trial of Atrial Fibrillation Investigators. N Engl J Med. 2000 Mar 30;342(13):913-20. doi: 10.1056/NEJM200003303421302. PMID: 10738049.