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Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. In spite of this the current treatment strategies are far from optimal. The different pathophysiologic mechanisms of AF are still not well defined. Structural changes in the atria including fibrosis and remodeling have been implicated in the pathogenesis of AF. Renin–angiotensin–aldosterone (RAA) system plays a role in AF by causing myocyte injury, proarrhythmic electrical remodeling, and atrial fibrosis. Suppression of the RAA system decreases the incidence of AF by reversing the cardiac structural and electrical changes.The extent of role aldosterone plays in this effect is unclear and the change in aldosterone levels in atrial tachyarrhythmias has not been evaluated before.
Wozakowska-Kaplon et al. measured the serum aldosterone levels in patients undergoing electrical cardioversion (EC) for persistent AF. Only patients with preserved left ventricular function, non valvular AF and well controlled AF were included. Forty three patients and 20 controls in sinus rhythm (SR) were enrolled. The mean baseline serum aldosterone level was higher in patients with persistent AF compared with the control group but it did not reach statistical significance (151.5 ± 90.7 pg/mL vs 129.6 ± 43.5 pg/mL; p = 0.11). The patients were further subdivided in to 2 subgroups: subgroup A comprising patients who remained in SR at 30 days and subgroup B comprising patients who did not. The subgroups did not have significant differences in clinical and echocardiographic characteristics. Serum aldosterone levels measured 24 hours after EC were significantly decreased compared to pre EC values in subgroup A but not in subgroup B. In all patients the serum aldosterone level decreased significantly within 24 hours after successful EC of AF (post-EC levels 109.5 ± 51.9 pg/mL; (p = 0.009). A majority of this may be due to subgroup A. Interestingly this group had very high pre-EC aldosterone levels.
Based on this the authors hypothesized that aldosterone levels may predict the ability to maintain SR after EC in persistent AF. Unchanged levels of aldosterone after EC may be a predictor of more advanced atrial disease with enhanced atrial expression of ACE and local aldosterone activation. The small number of patients and wide variation in aldosterone levels is a drawback of this study. It would be interesting to see if these results are replicated in a larger population and also in patients undergoing catheter ablation. The study also calls for a large prospective study to evaluate aldosterone antagonists in patients with AF undergoing DC cardioversion or AF ablation.
Wozakowska-Kaplon B, Bartkowiak R, Janiszewska G. A decrease in serum aldosterone level is associated with maintenance of sinus rhythm after successful cardioversion of atrial fibrillation. Pacing Clin Electrophysiol. 2010 May;33(5):561-5.
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