title: Effect of common KCNE1 and SCN5A ion channel gene variants on T-wave alternans, a marker of cardiac repolarization, during clinical exercise stress test: the Finnish Cardiovascular Study.
abstract: T-wave alternans (TWA) in electrocardiography (ECG) is a marker of cardiac repolarization, the molecular regulation of which is incompletely understood. High TWA and prolonged QT intervals are both associated with ventricular arrhythmias and sudden death. Therefore, we tested the hypothesis of whether the same mutations that influence the QT interval also affect TWA variation. We examined the effect of 3 ion channel gene single nucleotide polymorphisms (SNPs), rs1805127, rs727957 KCNE1, and rs1805124 SCN5A, on TWA during a clinical exercise test. A total of 2008 subjects from the Finnish Cardiovascular Study underwent an exercise test with online ECG recording. TWA was measured by using the time-domain, modified moving average method. Maximum values at rest, during maximal exercise, and during recovery were used as outcome measures in statistical analysis. Moreover, 4-year survival data were collected and ion channel SNPs were determined. TWA was lowest in subjects with the TT genotype of rs1805127 during all phases of the exercise test (RANOVA main effect for genotype, P = 0.018). The result remained significant after adjustment for age, existing coronary heart disease, and beta-blocker medication status (RANCOVA, P = 0.035). Of the polymorphisms studied, only rs1805127 had a significant association with mortality (P = 0.047). The most common G-C haplotype, formed by rs727957 and rs1805127, was associated with TWA (RANOVA, P = 0.007) but not with mortality. The rs1805124 polymorphism was not associated with TWA. The common KCNE1 gene variant rs1805127 is associated with TWA during an exercise test in a Finnish population, which provides additional evidence that KCNE1 genetics may influence cardiac repolarization and cardiovascular mortality.
authors.affiliation: Department of Internal Medicine, Tampere University Hospital and Medical School at the University of Tampere, Tampere, Finland. jenni.k.koskela@uta.fi
authors.forename: Jenni
authors.initials: J
authors.lastname: Koskela
authors.forename: Mika
authors.initials: M
authors.lastname: Kähönen
authors.forename: Meng
authors.initials: M
authors.lastname: Fan
authors.forename: Tuomo
authors.initials: T
authors.lastname: Nieminen
authors.forename: Rami
authors.initials: R
authors.lastname: Lehtinen
authors.forename: Jari
authors.initials: J
authors.lastname: Viik
authors.forename: Kjell
authors.initials: K
authors.lastname: Nikus
authors.forename: Kari
authors.initials: K
authors.lastname: Niemelä
authors.forename: Tiit
authors.initials: T
authors.lastname: Kööbi
authors.forename: Väinö
authors.initials: V
authors.lastname: Turjanmaa
authors.forename: Ilkka
authors.initials: I
authors.lastname: Pörsti
authors.forename: Terho
authors.initials: T
authors.lastname: Lehtimäki
mesh_terms: D017677:Age Distribution; D001145:Arrhythmias, Cardiac / Q000235:genetics / Q000401:mortality / Q000503:physiopathology; D015415:Biomarkers; D002318:Cardiovascular Diseases / Q000235:genetics* / Q000401:mortality / Q000503:physiopathology; D015331:Cohort Studies; D003710:Demography; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D005387:Finland; D006239:Haplotypes; D006321:Heart / Q000502:physiology; D006801:Humans; D008297:Male; D008564:Membrane Potentials / Q000235:genetics*; D008875:Middle Aged; D009026:Mortality; D009124:Muscle Proteins / Q000235:genetics*; D062554:NAV1.5 Voltage-Gated Sodium Channel; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics*; D012727:Sex Characteristics; D015222:Sodium Channels / Q000235:genetics*
chemical_list: D015415:Biomarkers; C489622:KCNE1 protein, human; D009124:Muscle Proteins; D062554:NAV1.5 Voltage-Gated Sodium Channel; D024642:Potassium Channels, Voltage-Gated; C568320:SCN5A protein, human; D015222:Sodium Channels