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 (I-Kr) and delayed (I-Ks) components of the outward potassium current 00, 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 I-K 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 beta-adrenergic activation of I-Ks may underlie the unusual repolarization behaviour. The unequal regression over time of Amiodarone-induced repolarization lengthening could have clinical significance. (c) 2007 Elsevier Ireland Ltd. All rights reserved.