[Antiarrhythmic drugs in paroxysmal atrial fibrillation. When and how?].

Atrial fibrillation (AF), carries a serious risk of systemic embolic complications, especially cerebral. Antiarrhythmic therapy is the most used method for restoring or maintaining sinus rhythm, and for preventing recurrences or of controlling the ventricular response. A clinical classification was recently suggested to define when to use antiarrhythmic drugs. In a first episode of symptomatic AF (Class I), it is not possible to assess the chances of recurrence and preventive antiarrhythmic therapy would not seem justified. In recurrent paroxysmal AF, the arrhythmias may be asymptomatic (Class IIa) and antiarrhythmic therapy may be questionned. When the attacks are infrequent (< 1 every 3 months, Class IIb), episodic pharmacological intervention to restore sinus rhythm or to slow the ventricular rate may be valuable, but the efficacy and safety of such treatment should be assessed. In Class IIc, appropriate antiarrhythmic treatment to prevent recurrence is often indicated. Atrial fibrillation resistant to one or more antiarrhythmic drugs (Class III) may also be subdivised into three subgroups as for Class II. In addition to the use of alternating of antiarrhythmic drugs not previously used, it is justifiable to consider investigations to determine the mechanism of resistant AF use only drugs of the which slow the ventricular rate. The choice of antiarrhythmic drug may be guided by the concepts of the Silician Gambit, taking into consideration the mechanism of AF and the therapeutic objective. In AF, the mechanism is reentry, the vulnerable parameter the atrial refractory period. To increase the refractory period, the target should be the sodium or potassium currents. The status of left ventricular function is an important parameter in the choice of an antiarrhythmic agent.