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Summary. Purpose: To assess the effects of amiodarone and diltiazem on atrial fibrillation (AF) induced atrial electrical remodeling and their clinical implications.
Methods: Persistent AF patients were randomly assigned to three treatment groups over a period from 6 weeks before to 6 weeks after internal cardioversion: group A (35 patients, oral diltiazem), group B (34 patients, oral amiodarone) and group C (37 patients, no antiarrhythmic drugs). Several electrophysiological parameters were assessed 5 min and 24 h after cardioversion.
Results: Compared with controls, group B patients had significantly higher conversion rates (83% vs. 100%, p = 0.041) and a higher probability to maintain sinus rhythm (p=0.037). Patients of group B had longer fibrillatory cycle length intervals than patients of group A and C (180+ or -18 ms vs. 161+ or -17 ms vs. 164+ or -19 ms, p = 0.001) and longer atrial effective refractory periods (211+ or -22 ms vs. 198+ or -16 ms vs. 194+ or -17 ms, p = 0.003) as assessed 5 min after conversion. Post-conversion density of supraventricular ectopics was significantly lower in group B compared to groups A and C (p= 0.001).
Conclusions: Oral amiodarone increases conversion rates, prolongs fibrillatory cycle length and atrial effective refractory period and preserves sinus rhythm after cardioversion in persistent AF patients by suppressing the atrial ectopics that trigger AF.
Key Words. atrial fibrillation, remodeling, recurrence, diltiazem, amiodarone
Introduction
In recent years emphasis has been given to the concept of atrial electrical remodeling that results from atrial tachyarrhythmias and its implication in initiation, recurrence and drug resistance of atrial fibrillation [1-14]. In the case of persistent atrial fibrillation, the abnormal atrial electrophysiology associated with atrial electrical remodeling has been attributed to changes in the expression of the genes that determine the function of specific ionic channels especially those of ICaL [7,8]. L-type calcium blockers, such as verapamil or diltiazem, have been proposed as potentially useful drugs for patients with atrial fibrillation, since these drugs theoretically could decrease the deleterious cytosolic calcium concentrations that have been implicated as the major contributing factor in the development of atrial electrical remodeling [15-17]. Clinical studies [17-21] that included persistent atrial fibrillation patients who were pretreated with various calcium blockers and subsequently electroverted to sinus rhythm have shown conflicting...