Knock-in gain-of-function sodium channel mutation prolongs atrial action potentials and alters atrial vulnerability

Andreas Blana, Sven Kaese, Lisa Fortmueller, Sandra Laakmann, Dierk Damke, Kelly van Bragt, Jens Eckstein, Ilaria Piccini, Uwe Kirchhefer, Stanley Nattel, Guenter Breithardt, Peter Carmeliet, Edward Carmeliet, Ulrich Schotten, Sander Verheule, Paulus Kirchhof, Larissa Fabritz*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

BACKGROUND Patients with long QT syndrome (LQTS) are at increased risk not only for ventricular arrhythmias but also for atrial pathology including atrial fibrillation (AF). Some patients with "lone" AF carry Na(+)-channel mutations. OBJECTIVE The purpose of this study was to determine the mechanisms underlying atrial pathology in LQTS. METHODS In mice with a heterozygous knock-in long QT syndrome type 3 (LQT3) mutant of the cardiac Na(+) channel (Delta KPQ-SCN5A) and wild-type (WT) littermates, atrial size, function, and electrophysiologic parameters were measured in intact Langendorff-perfused hearts, and histologic analysis was performed. RESULTS Atrial action potential duration, effective refractory period, cycle length, and PQ interval were prolonged in Delta KPQ-SCN5A hearts (all P <.05). Flecainide (1 mu M) reversed atrial action potential duration prolongation and induced postrepolarization refractoriness (P <.05). Arrhythmias were infrequent during regular rapid atrial rate in both WT and Delta KPQ-SCN5A but were inducible in 15 (38%) of 40 Delta KPQ-SCN5A and 8 (29%) of 28 WT mice upon extrastimulation. Pacing protocols generating rapid alterations in rate provoked atrial extrasystoles and arrhythmias in 6 66%) of 9 Delta KPQ-SCN5A but in 0 (0%) of 6 WT mice (P <.05). Atrial diameter was increased by nearly 10% in Delta KPQ-SCN5A mice > 5 months old without increase in fibrotic tissue. CONCLUSION Murine hearts bearing an LQT3 mutation show abnormalities in atrial electrophysiology and subtle changes in atrial dimension, including an atrial arrhythmogenic phenotype on provocation. These results support clinical data suggesting that LQTS mutations can cause atrial pathology and arrhythmogenesis and indicate that murine sodium channel LQTS models may be useful for exploring underlying mechanisms.
Original languageEnglish
Pages (from-to)1862-1869
JournalHeart Rhythm
Volume7
Issue number12
DOIs
Publication statusPublished - Dec 2010

Keywords

  • Antiarrhythmic drugs
  • Atrial remodeling
  • Electrophysiology
  • Genetic models
  • Nav1.5

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