title: Inter-subject variability in human atrial action potential in sinus rhythm versus chronic atrial fibrillation.
abstract: OBJECTIVE
  Human atrial electrophysiology exhibits high inter-subject variability in both sinus rhythm (SR) and chronic atrial fibrillation (cAF) patients. Variability is however rarely investigated in experimental and theoretical electrophysiological studies, thus hampering the understanding of its underlying causes but also its implications in explaining differences in the response to disease and treatment. In our study, we aim at investigating the ability of populations of human atrial cell models to capture the inter-subject variability in action potential (AP) recorded in 363 patients both under SR and cAF conditions.
  
  
  RESULTS
  Human AP recordings in atrial trabeculae (n = 469) from SR and cAF patients were used to calibrate populations of computational SR and cAF atrial AP models. Three populations of over 2000 sampled models were generated, based on three different human atrial AP models. Experimental calibration selected populations of AP models yielding AP with morphology and duration in range with experimental recordings. Populations using the three original models can mimic variability in experimental AP in both SR and cAF, with median conductance values in SR for most ionic currents deviating less than 30% from their original peak values. All cAF populations show similar variations in G(K1), G(Kur) and G(to), consistent with AF-related remodeling as reported in experiments. In all SR and cAF model populations, inter-subject variability in I(K1) and I(NaK) underlies variability in APD90, variability in I(Kur), I(CaL) and I(NaK) modulates variability in APD50 and combined variability in Ito and I(Kur) determines variability in APD20. The large variability in human atrial AP triangulation is mostly determined by I(K1) and either I(NaK) or I(NaCa) depending on the model.
  
  
  CONCLUSIONS
  Experimentally-calibrated human atrial AP models populations mimic AP variability in SR and cAF patient recordings, and identify potential ionic determinants of inter-subject variability in human atrial AP duration and morphology in SR versus cAF.
authors.affiliation: Biosignal Interpretation and Computational Simulation (BSICoS), Aragón Institute of Engineering Research (I3A) and Aragón Health Research Institute (IIS), University of Zaragoza, Zaragoza, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain; Department of Computer Science, University of Oxford, Oxford, United Kingdom.
authors.forename: Carlos
authors.initials: C
authors.lastname: Sánchez
authors.affiliation: Department of Computer Science, University of Oxford, Oxford, United Kingdom.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Bueno-Orovio
authors.affiliation: Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany.
authors.forename: Erich
authors.initials: E
authors.lastname: Wettwer
authors.affiliation: Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Loose
authors.affiliation: Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Simon
authors.affiliation: Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Ravens
authors.affiliation: Biosignal Interpretation and Computational Simulation (BSICoS), Aragón Institute of Engineering Research (I3A) and Aragón Health Research Institute (IIS), University of Zaragoza, Zaragoza, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Zaragoza, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Pueyo
authors.affiliation: Department of Computer Science, University of Oxford, Oxford, United Kingdom.
authors.forename: Blanca
authors.initials: B
authors.lastname: Rodriguez
mesh_terms: D000200:Action Potentials; D001281:Atrial Fibrillation / Q000503:physiopathology*; D001283:Atrioventricular Node / Q000503:physiopathology*; D002908:Chronic Disease; D006329:Heart Conduction System; D006801:Humans; D009200:Myocardial Contraction; D012849:Sinoatrial Node / Q000503:physiopathology*