Acquired long QT syndrome: Unequal regression of Amiodarone-induced repolarization lengthening

We describe full exposure of an acquired Long QT Syndrome (aLQTS) in an elderly female patient on long-term Amiodarone treatment. We propose that the aLQTS is the result of combined block of the rapid (IKr) and delayed (IKs) components of the outward potassium current (IK), translated to the ECG in a (more than expected) prolonged QT interval, an augmented transmural dispersion of repolarization (TDR) and an interrupted T wave. The unequal regression of repolarization lengthening made possible to individualize IK current components in the inscription of the interrupted T wave, which argues against the U wave as a separate entity. Silent ion channel gene mutations or polymorphisms and downregulation of β-adrenergic activation of IKs may underlie the unusual repolarization behaviour. The unequal regression over time of Amiodarone-induced repolarization lengthening could have clinical significance.