BackgroundAtrial fibrillation (AF) is the most common arrhythmia in adults, and is
encountered in 10-15% of the patients with hyperthyroidism. Unless
euthyroidism is restored, pharmacological or electrical cardioversion is
controversial in patients with AF who remain hyperthyroid.ObjectiveThe aim of this study was to assess the efficacy of electrical cardioversion
and predictors of AF recurrence in hyperthyroid and euthyroid patients.MethodsThe study included 33 hyperthyroid (21 males) and 48 euthyroid (17 males)
patients with persistent AF. The patients were sedated with intravenous
midazolam before undergoing electrical cardioversion delivered by
synchronized biphasic shocks. Rates of AF recurrence were recorded.ResultsMean follow-up was 23.63 ± 3.74 months in the hyperthyroid group and
22.78 ± 3.15 months in the euthyroid group (p = 0.51). AF recurred in
14 (43.8%) and 21 (44.7%) patients in each group, respectively (p = 0.93).
Multivariate regression analysis in each group showed that AF duration was
the only predictor of AF recurrence, with odds ratios of 1.38 (95%
confidence interval [CI] = 1.05 - 1.82, p = 0.02) in the hyperthyroid group
and 1.42 (95% CI = 1.05 - 1.91, p= 0.02) in the euthyroid group.ConclusionRates of long-term AF recurrence were similar in successfully cardioverted
hyperthyroid and euthyroid patients. The only predictor of AF recurrence in
both groups was AF duration.