Although hyperthyroidism isconsidered a reversible cause of AF, only two-thirds of the patients returnspontaneously to an SR after their thyroid hormone levels return tonormal.8 For patients whoachieve euthyroidism but persist with AF, cardioversion is an option.6,9 However, since the risk of thromboembolism is substantial in AFpatients, the decision to postpone cardioversion until euthyroidism is restored iscontroversial. Here, TG is linked to atrial fibrillation.