Background: Atrial fibrillation (AF) is the most common cardiac complication of hyperthyroidism.
The influence of the time of cardioversion on hyperthyroidism-induced AF remains
unclear. The aim of this study was to compare short-term outcomes of early electrical
cardioversion for AF in hyperthyroid and euthyroid patients.
Methods and Results: Sixty-seven subjects with persistent AF (duration, 10 days–12 months)
were divided into two groups according to thyroid function: Euthyroid (Group 1, n = 36,
female/male: 23/13, mean age: 61.77 ± 10.45 years) and hyperthyroid (Group 2, n = 31,
female/male: 10/21, mean age: 65.43 ± 6.40 years). Two patients were excluded for unsuccessful
cardioversion (one in each group). In Group 2, 19 patients had clinical and 11 had
subclinical hyperthyroidism. Following transthoracic and transesophageal echocardiography,
cardioversion was performed until the highest energy was reached (270 J) or until sinus
rhythm was achieved. AF recurrence was detected in 13 of 35 patients (37.1%) in Group 1 and
in 11 of 30 patients (36.9%) in Group 2 (p = 0.96) at one month. Recurrence rate was higher
in the clinical hyperthyroid patients than in the subclinical hyperthyroid patients (52.6% vs
9.1%, p = 0.021), but neither the clinical nor the subclinical hyperthyroid subgroups were significantly
different from Group 1 in terms of recurrence rate (p = 0.27 and p = 0.13, respectively).
Conclusions: Electrical cardioversion should be performed for patients with persistent AF
and hyperthyroidism as soon as possible. (Cardiol J 2012; 19, 1: 53–60