Post-operative atrial fibrillation is influenced by beta-blocker therapy but not by pre-operative atrial cellular electrophysiology.
BACKGROUND
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.


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 Ca(2+) 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 (approximately 20%) in those with and without post-CS AF.


CONCLUSIONS
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.
Workman
Antony J
AJ
BHF Glasgow Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow G12 8TA, United Kingdom. A.J.Workman@clinmed.gla.ac.uk
Pau
Davide
D
Redpath
Calum J
CJ
Marshall
Gillian E
GE
Russell
Julie A
JA
Kane
Kathleen A
KA
Norrie
John
J
Rankin
Andrew C
AC
D000200:Action Potentials / Q000502:physiology; D000319:Adrenergic beta-Antagonists / Q000009:adverse effects*; D000367:Age Factors; D000368:Aged; D001281:Atrial Fibrillation / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006325:Heart Atria / Q000166:cytology; D006801:Humans; D008297:Male; D008875:Middle Aged; D032383:Myocytes, Cardiac / Q000502:physiology; D011183:Postoperative Complications / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology*; D011300:Preoperative Care / Q000379:methods
D000319:Adrenergic beta-Antagonists