![]() We suggested that notched T waves on ECGs and Holter recordings in family members with a HERG A561T mutation were linked to the presence of that mutation. LQT3 patients show distinctive T waves of late onset, whereas LQT1 or LQT2 patients display broad-based or low-amplitude T waves, respectively. 9 Moss et al 10 reported that patients with ion channel defects often display different T-wave patterns. 8 Furthermore, this pattern has been associated with a poor prognosis. In addition to duration, T-wave morphology is often abnormal, and notched T waves have been included in diagnostic criteria. 4 5 6 7 LQTS patients exhibit QT prolongation on the ECG and are at risk of arrhythmogenic syncope and sudden death. Mutations in the N- and C-terminal domains, however, have also been reported. Most mutations have been identified in the core domain, constituted by the transmembrane domains and the pore, of KCNQ1 and HERG. 1 Five LQTS genes have been identified, including the potassium channel genes HERG KCNH2 (LQT2), 2 which encodes the α-subunit of the channel that underlies the rapidly activating delayed rectifier potassium current I Kr and KCNQ1 (LQT1), 3 which encodes the slowly activating delayed rectifier potassium channel I Ks. Genetic studies have shown that long-QT syndrome (LQTS) is a primary electrical disease caused by mutations in specific ion channels. These repolarization abnormalities are more indicative of LQT2 versus LQT1, with G2 notches being most specific and often reflecting HERG core domain missense mutations. Predictors for G2 were young age, missense mutations, and core domain mutations in HERG.Ĭonclusions-This study provides novel evidence that Holter recording analysis is superior to the 12-lead ECG in detecting G1 and G2 T-wave notches. G1 notches were relatively more frequent in LQT2 (18% versus 8% and 4%, P<0.01), and G2 notches were seen exclusively in LQT2 (63%). T-wave morphology was normal in the majority of LQT1 and control subjects compared with LQT2 (92%, 96%, and 19%, respectively, P<0.001). ![]() The highest grade obtained from a template defined the notch category of the subject. ![]() 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. Methods and Results-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. In addition to QT-interval prolongation, notched T waves have been proposed as a phenotypic marker of LQTS patients. Customer Service and Ordering Informationīackground-The 2 genes KCNQ1 (LQT1) and HERG (LQT2), encoding cardiac potassium channels, are the most common cause of the dominant long-QT syndrome (LQTS).Stroke: Vascular and Interventional Neurology.Journal of the American Heart Association (JAHA).Circ: Cardiovascular Quality & Outcomes.Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB). ![]()
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