ANTIARRHYTHMIC DRUG-THERAPY TO PREVENT RE CURRENCES OF PAROXYSMAL OR CHRONIC ATRIAL-FIBRILLATION

In many patients with paroxysmal or chronic atrial fibrillation, long- term antiarrhythmic drug therapy is performed to prevent recurrences o f atrial fibrillation or to reduce the incidence of paroxysmal attacks of atrial fibrillation. The results of several studies on the efficac y of antiarrhythmic drugs in patients with paroxysmal atrial fibrillat ion have revealed that the incidence of recurrent attacks of atrial fi brillation can be reduced and the duration of arrhythmia free interval s can be prolonged by antiarrhythmic drug therapy. However, complete p revention of atrial fibrillation can be achieved only in a minority of patients. At present, there is no evidence that antiarrhythmic drug t reatment of patients with paroxysmal atrial fibrillation might worsen the prognosis by an increase in cardiac mortality induced by antiarrhy thmic drugs. in patients with chronic atrial fibrillation, the recurre nce rate of the arrhythmia can be significantly reduced by antiarrhyth mic drug therapy within the first year of treatment. However, there is evidence that antiarrhythmic drugs might worsen the prognosis when co mpared to patients with atrial fibrillation not treated with antiarrhy thmic drugs. Accordingly, the indication for antiarrhythmic drug thera py to prevent recurrences in patients with chronic atrial fibrillation has to be made restrictively and should be largely based on the sympt omatic status of the patients. Antiarrhythmic drug therapy seems to be indicated only in patients who are significantly symptomatic or compr omised by the arrhythmia. In patients without or with only mild sympto ms, medical therapy with the aim to slow the ventricular response with digitalis, calcium antagonists or betablocking agents seems to be mor e adequate. Currently, with respect to efficacy and safety, there is n o antiarrhythmic drug that has been proved to be superior to others an d that can thus be recommended as the drug of first choice for patient s with paroxysmal or chronic atrial fibrillation to prevent recurrence s. The choice of the optimal antiarrhythmic drug should be made by tak ing individual factors (e.g., etiology of the arrhythmia, patient comp liance, liver and renal function of the patient, additional medical th erapy) into account. Major problems during long-term antiarrhythmic dr ug therapy may arise in patients with pre-existing sinus node dysfunct ion or conduction disturbances of the atrioventricular node. In additi on, the conversion of atrial fibrillation with relatively slow ventric ular rates to the atrial flutter with fast ventricular rates that is o ccasionally observed during treatment with class I-antiarrhythmic drug s may complicate longterm therapy. After antiarrhythmic drug therapy h as been initiated, the patients require further careful medical contro l to recognize ineffective drug therapy as well as significant side-ef fects of antiarrhythmic therapy or potential hazards such as those ari sing from electrolyte imbalances.