Pretreatment of patients with atrial fibrillation who undergo electrical cardioversion.

Who Undergo Electrical Cardioversion To the Editor: We read with interest the study by Madrid et al1 in a recent issue of Circulation. They investigated the role of pretreatment with amiodarone alone or combined with irbesartan in patients with long-lasting persistent atrial fibrillation, and concluded that adding irbesartan to amiodarone reduces recurrences. Nonetheless, some points should be stressed. They reported no significant difference in the baseline concomitant medication between the two groups. However, the percentage of both -blockers, and calcium-channel blockers, is higher in the irbesartan group (15% versus 7%, P 0.09, and 9% versus 5%, P 0.3, respectively). Because both decrease intracellular calcium, we believe that both medications should be considered together. When Tieleman et al2 first demonstrated the role of calciumlowering drugs in reducing recurrences of atrial fibrillation after electrical cardioversion, the proportion of patients taking calcium antagonists or -blockers before cardioversion was of borderline significance (P 0.06 and P 0.08, respectively). When considering the overall intracellular calcium-lowering drugs, the proportion became significant (P 0.04). Arranging the Madrid et al data in a similar way, the percentage of calcium-lowering drugs might become statistically significantly lower in the amiodarone group. This could explain part of the lower recurrence rate of atrial fibrillation in the irbesartan group. Moreover, the findings that most of the benefit of irbesartan occurred during the first 2 months after cardioversion supports our hypothesis that the higher prevalence of calcium lowering drugs in the irbesartan group plays a role in the benefit of irbesartan. As we and other groups have demonstrated, calcium-lowering drugs significantly decrease the early recurrence of atrial fibrillation,2,3 whereas an angiotensin I type 1 receptor blocker is expected to improve the structural remodeling during a period of months.4