Referenced in: none

Automatically associated channels: Kir2.1 , Kv11.1 , Kv7.1

Title: Short QT syndrome.

Authors: Rainer Schimpf, Christian Wolpert, Fiorenzo Gaita, Carla Giustetto, Martin Borggrefe

Journal, date & volume: Cardiovasc. Res., 2005 Aug 15 , 67, 357-66

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/15890322

Abstract
The short QT syndrome constitutes a new clinical entity that is associated with a high incidence of sudden cardiac death, syncope, and/or atrial fibrillation even in young patients and newborns. Patients with this congenital electrical abnormality are characterized by rate-corrected QT intervals<320 ms. Missense mutations in KCNH2 (HERG) linked to a gain-of-function of the rapidly activating delayed-rectifier current I(Kr) have been identified in the first two reported families with familial sudden cardiac death. Recently, two further gain-of-function mutations in the KCNQ1 gene encoding the alpha-subunit of the KvLQT1 (I(Ks)) channel and in the KCNJ2 gene encoding the strong inwardly rectifying channel protein Kir2.1 confirmed a genetically heterogeneous disease. The possible substrate for the development of ventricular tachyarrhythmias may be a significant transmural dispersion of the repolarisation due to a heterogeneous abbreviation of the action potential duration. The implantable cardioverter defibrillator is the therapy of choice in patients with syncope and a positive family history of sudden cardiac death. However, ICD therapy in patients with a short QT syndrome has an increased risk for inappropriate shock therapies due to possible T wave oversensing. The impact of sotalol, ibutilide, flecainide, and quinidine on QT prolongation has been evaluated, but only quinidine effectively suppressed gain-of-function in I(Kr) with prolongation of the QT interval. In patients with a mutation in HERG, it rendered ventricular tachycardias/ventricular fibrillation non-inducible and restored the QT interval/heart rate relationship towards a normal range. It may serve as an adjunct to ICD therapy or as a possible alternative treatment, especially for children and newborns.