Anti-arrhythmic medication is used to control heart rhythm by generally slowing it down and making it more regular. The antiarrhythmics can be very effective, but they may also have significant side effects and in certain situations, even paradoxical pro-arrhythmogenic effect; i.e. they may increase the risk of serious arrhythmias. Beta-blockers have important anti-arrhythmic properties, but they are usually not considered antiarrhythmics. The most common anti-arrhythmic drugs are flecainide and amiodarone.


Flecainide is often used in paroxysmal atrial fibrillation combined with a small dose of beta-blocker (flecainide alone may convert atrial fibrillation into atrial flutter with fast ventricular response). The starting dose is normally 50mg bd (twice daily); if needed, it can be later increased to 100mg bd. Flecainide may be safely prescribed only in patients with a structurally normal heart. Flecainide is usually well tolerated, but it can sometimes cause nausea, dizziness, and blurred vision.


Amiodarone is a very effective antiarrhythmic that can be used even in patients with a structural cardiac problem or heart failure, but it has several potential side effects which limit its long-term use. Amiodarone can cause problems with the thyroid, lungs, and liver and requires, therefore, regular blood samples every six months. Patients on amiodarone must keep alcohol intake at a minimum well below 14 units a week. Amiodarone also causes photosensitivity, i.e. makes skin sensitive to sunlight, which requires high-factor sun cream in the sunshine. A similar drug to amiodarone is dronedarone, but it is rarely used because of the need for extensive monitoring

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