IngentaConnect Post-Operative Atrial Fibrillation Is Influenced by Beta-Blocker ...

Authors: WORKMAN, ANTONY J.¹; PAU, DAVIDE¹; REDPATH, CALUM J.¹; MARSHALL, GILLIAN E.¹; RUSSELL, JULIE A.¹; KANE, KATHLEEN A.²; NORRIE, JOHN³; RANKIN, ANDREW C.¹

Source: Journal of Cardiovascular Electrophysiology, Volume 17, Number 11, November 2006 , pp. 1230-1238(9)

Publisher: Blackwell Publishing

Abstract:

Post-Operative AF, Beta-Blockade, and Atrial Electrophysiology.

Introduction: We investigated whether post-cardiac surgery (CS) new-onset atrial fibrillation (AF) is predicted by pre-CS atrial cellular electrophysiology, and whether the antiarrhythmic effect of beta-blocker therapy may involve pre-CS pharmacological remodeling.

Methods and Results: Atrial myocytes were obtained from consenting patients in sinus rhythm, just prior to CS. Action potentials and ion currents were recorded using whole-cell patch-clamp technique. Post-CS AF occurred in 53 of 212 patients (25%). Those with post-CS AF were older than those without (67 ± 2 vs 62 ± 1 years, P = 0.005). In cells from patients with post-CS AF, the action potential duration at 50% and 90% repolarization, maximum upstroke velocity, and effective refractory period (ERP) were 13 ± 4 ms, 217 ± 16 ms, 185 ± 10 V/s, and 216 ± 14 ms, respectively (n = 30 cells, 11 patients). Peak L-type Ca²⁺ current, transient outward and inward rectifier K⁺ currents, and the sustained outward current were −5.0 ± 0.5, 12.9 ± 2.4, −4.1 ± 0.4, and 9.7 ± 1.0 pA/pF, respectively (13-62 cells, 7-19 patients). None of these values were significantly different in cells from patients without post-CS AF (P > 0.05 for each, 60-279 cells, 29-86 patients), confirmed by multiple and logistic regression. In patients treated >7 days with a beta-blocker pre-CS, the incidence of post-CS AF was lower than in non-beta-blocked patients (13% vs 27%, P = 0.038). Pre-CS beta-blockade was associated with a prolonged pre-CS atrial cellular ERP (P = 0.001), by a similar degree (∼20%) in those with and without post-CS AF.

Conclusion: Pre-CS human atrial cellular electrophysiology does not predict post-CS AF. Chronic beta-blocker therapy is associated with a reduced incidence of post-CS AF, unrelated to a pre-CS ERP-prolonging effect of this treatment.

(J Cardiovasc Electrophysiol, Vol. 17, pp. 1230-1238, November 2006)

Keywords: atrial fibrillation/atrial arrhythmias; cellular electrophysiology/electropharmacology; ion channels; membrane transporters

Document Type: Research article

DOI: 10.1111/j.1540-8167.2006.00592.x

Affiliations: 1: BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK 2: Department of Physiology and Pharmacology, University of Strathclyde, Glasgow, UK 3: Centre for Healthcare Randomised Trials, University of Aberdeen, Aberdeen, UK

Post-Operative Atrial Fibrillation Is Influenced by Beta-Blocker Therapy But Not by Pre-Operative Atrial Cellular Electrophysiology