Atrial cellular electrophysiological changes in patients with ventricular dysfunction may predispose to AF

Antony J. Workman*, Davide Pau, Calum J. Redpath, Gillian E. Marshall, Julie A. Russell, John Norrie, Kathleen A. Kane, Andrew C. Rankin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Left ventricular systolic dysfunction (LVSD) is a risk factor for atrial fibrillation (AF), but the atrial cellular electrophysiological mechanisms in humans are unclear. Objective: This study sought to investigate whether LVSD in patients who are in sinus rhythm (SR) is associated with atrial cellular electrophysiological changes that could predispose to AF. Methods: Right atrial myocytes were obtained from 214 consenting patients in SR who were undergoing cardiac surgery. Action potentials or ion currents were measured using the whole-cell-patch clamp technique. Results: The presence of moderate or severe LVSD was associated with a shortened atrial cellular effective refractory period (ERP) (209 ± 8 ms; 52 cells, 18 patients vs 233 ± 7 ms; 134 cells, 49 patients; P <0.05); confirmed by multiple linear regression analysis. The left ventricular ejection fraction (LVEF) was markedly lower in patients with moderate or severe LVSD (36% ± 4%, n = 15) than in those without LVSD (62% ± 2%, n = 31; P <0.05). In cells from patients with LVEF ≤ 45%, the ERP and action potential duration at 90% repolarization were shorter than in those from patients with LVEF > 45%, by 24% and 18%, respectively. The LVEF and ERP were positively correlated (r = 0.65, P <0.05). The L-type calcium ion current, inward rectifier potassium ion current, and sustained outward ion current were unaffected by LVSD. The transient outward potassium ion current was decreased by 34%, with a positive shift in its activation voltage, and no change in its decay kinetics. Conclusion: LVSD in patients in SR is independently associated with a shortening of the atrial cellular ERP, which may be expected to contribute to a predisposition to AF.

Original languageEnglish
Pages (from-to)445-451
Number of pages7
JournalHeart Rhythm
Volume6
Issue number4
DOIs
Publication statusPublished - 5 Jan 2009

Keywords

  • Action potential duration
  • Atrial fibrillation
  • Effective refractory period
  • Ejection fraction
  • Electrophysiological remodeling
  • Human
  • Ion current
  • Isolated myocyte
  • Left ventricular systolic dysfunction
  • Sinus rhythm

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