Recurrence of atrial fibrillation in hyperthyroidism related atrial fibrillation: a matched case-control study

Abstract

INTRODUCTION: Although hyperthyroidism related AF usually reverts to sinus rhythm after the return of euthyroid state, whether hyperthyroidism related AF after sinus conversion carries a lower risk of recurrence remains unclear. METHODS: We prospectively studied the AF recurrence rate in 37 hyperthyroid patients with self-terminated AF (48±2 years, male 57%) and 58 hyperthyroid patients with persistent AF converted by electrical cardioversion (57±2 years, male 72%). Age- and sex-matched non-thyroid patients with self-terminated AF and with persistent AF converted by electrical cardioversion were compared. RESULTS: After 29±4 months of follow-up, 14 hyperthyroid patients with self-terminated AF (38%) and 34 hyperthyroid patients with persistent AF converted by electrical cardioversion (59%) developed AF recurrence, which were significantly lower than the non-hyperthyroid controls: 62% (Hazard Ratio (HR): 0.39, 95% confidence interval (CI): 0.18-0.71, P<0.01) and 83% (HR: 0.64, 95% CI: 0.39-0.97, P=0.04) respectively. In Cox regression analysis, only low thyroxine level predicted AF recurrence in hyperthyroid patients with self-terminated AF, whereas long AF duration predicts AF recurrence in hyperthyroid patients with persistent AF. CONCLUSIONS: Hyperthyroidism related AF carries a lower recurrence rate after sinus version. Early electrical cardioversion should be considered in management of hyperthyroid patients with persistent AF.