Prolongation of the QT interval in patients with hypothyroidism reportedly occurs in 21-33%, but complications of ventricular arrhythmias such as TdP are rare [7]. It has been suggested that thyroid hormones control the expression of potassium channels such as Kv1.5 or Kv4.2. Here, KCNA3 is linked to Ventricular arrhythmia.