Referenced in: none

Automatically associated channels: Kv11.1 , Kv7.1

Title: Notched T waves on Holter recordings enhance detection of patients with LQt2 (HERG) mutations.

Authors: J M Lupoglazoff, I Denjoy, M Berthet, N Neyroud, L Demay, P Richard, B Hainque, G Vaksmann, D Klug, A Leenhardt, G Maillard, P Coumel, P Guicheney

Journal, date & volume: Circulation, 2001 Feb 27 , 103, 1095-101

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/11222472

Abstract
The 2 genes KCNQ1 (LQT1) and HERG (LQT2), encoding cardiac potassium channels, are the most common cause of the dominant long-QT syndrome (LQTS). In addition to QT-interval prolongation, notched T waves have been proposed as a phenotypic marker of LQTS patients.The T-wave morphology of carriers of mutations in KCNQ1 (n=133) or HERG (n=57) and of 100 control subjects was analyzed from Holter ECG recordings. Averaged T-wave templates were obtained at different cycle lengths, and potential notched T waves were classified as grade 1 (G1) in case of a bulge at or below the horizontal, whatever the amplitude, and as grade 2 (G2) in case of a protuberance above the horizontal. The highest grade obtained from a template defined the notch category of the subject. T-wave morphology was normal in the majority of LQT1 and control subjects compared with LQT2 (92%, 96%, and 19%, respectively, P:<0.001). G1 notches were relatively more frequent in LQT2 (18% versus 8% [LQT1] and 4% [control], P:<0.01), and G2 notches were seen exclusively in LQT2 (63%). Predictors for G2 were young age, missense mutations, and core domain mutations in HERG.This study provides novel evidence that Holter recording analysis is superior to the 12-lead ECG in detecting G1 and G2 T-wave notches. These repolarization abnormalities are more indicative of LQT2 versus LQT1, with G2 notches being most specific and often reflecting HERG core domain missense mutations.