Pharmacologic Cardioversion of Atrial Fibrillation: Always the Same Algorithm or Different Drugs for Different Patients?

Abstract

The clinical use of class IC antiarrhythmic drugs and amiodarone during the last 10 years has represented a great achievement in the restoration of the sinus rhythm during atrial fibrillation (AF) of recent onset. In fact, the advantages of the pharmacologic treatment depend not only on the effectiveness of these drugs (quinidine, a very old drug, has also shown an effectiveness in the range of 30% – 91%), but much more on the velocity of the sinus rhythm restoration, often during the intravenous infusion of the drug. This avoids patient hospitalization. The drugs mainly employed in the treatment of AF are 1A and 1C antiarrhythmic agents, amiodarone, and sometimes verapamil, beta-blocking agents, and digoxin. Clinical practice suggests that the appropriate drug be chosen in each individual situation. However, before discussing the different clinical situations in which AF may occur, we must emphasize that to our knowledge no homogeneous, controlled, and randomized studies in large groups of patients that suggest the correct way of treating this arrhythmia have been performed. In fact, in all the studies patients the group were heterogenous as far as the etiology of heart disease and the duration of AF were different. In our opinion, however, it is possible to suggest some guidelines about the clinical use of different drugs in different patients using our knowledge of the electrophysiologic and hemodynamic properties of drugs, their effectiveness, and side effects occurring in clinical practice. Regarding cardioversion, if we take into account anticoagulant prophylaxis, it is useful to divide AF in-to AF of recent onset (less than 3 days) and prolonged AF (more than 3 days). In fact, according to the College of Chest Physicians (1), AF with a duration longer than 3 days needs to be treated with anticoagulant drugs for at least 3 weeks before cardioversion. Therefore, this practice identifies two groups of patients with AF: the first group can be treated within 3 days, and the second cannot be treated before 3 weeks. It is well known that AF duration is the main factor conditioning the probability of sinus rhythm restoration (2). As we now have several drugs whose effectiveness may be different according to AF duration, it follows that AF duration is one of the main factors determining the choice of drug.