What drugs should be used to maintain someone in sinus rhythm who has paroxysmal atrial fibrillation? Is there a role for digoxin?

The natural history of patients with paroxysmal atrial fibrillation is that over a period of time (and often many years) there is a gradual tendency to an increased frequency and duration of attacks. A proportion of patients will develop chronic atrial fibrillation. Not all patients require antiarrhythmic drugs and the potential side effects and inconvenience of regular medication must be balanced against the frequency of episodes and symptomatology which vary markedly between patients. Triggers include alcohol and caffeine, ischaemia, untreated hypertension (which if aggressively managed can at least in the short term obviate the need for antiarrhythmics), thyrotoxicosis, and in a small proportion of patients vagal or sympathetic stimulation where attacks are typically preceded by a drop in heart rate or exercise respectively.

The most effective drugs are also those with potentially dangerous side effects. The risks of class 1 agents (such as flecainide, disopyramide and propafenone) in patients with underlying coronary artery disease are well recognised and are best avoided. In younger patients (where it is presumed the associated risks are proportionately less) they can be highly effective. Sotalol may be useful in some patients but adequate dosing is required to achieve class 3 antiarrhythmic activity and not all patients will tolerate the associated degree of beta blockade. Amiodarone can be highly effective but its use is limited by the incidence of serious side effects. Beta blockers and calcium channel blockers have no role in preventing paroxysms of atrial fibrillation but can help certain patients in reducing the rate and so symptomatology.

Despite the long-standing conviction of many clinicians that digoxin is efficacious in the management of paroxysmal atrial fibrillation it has been clearly shown that digoxin neither reduces the frequency of attacks nor produces any useful reduction of heart rate during paroxysms of atrial fibrillation. Furthermore a number of placebo-controlled studies designed to explore the possibility that digoxin might chemically cardiovert patients with recent onset atrial fibrillation have shown no effect of digoxin as compared with placebo. Hence there appears to be no role for digoxin.