Atrial fibrillation after coronary artery bypass grafting is associated with sympathetic activation.
BACKGROUND
We prospectively investigated the role of sympathetic activation in the etiology of atrial fibrillation following coronary artery bypass grafting.


METHODS
Continuous ambulatory monitoring was performed for 80 hours in 131 patients after coronary artery bypass grafting. Right atrial plasma norepinephrine levels were assessed preoperatively and every 4 hours for 48 hours postoperatively.


RESULTS
Of the 131 patients, 50% (65) had development of atrial fibrillation and 36% (47) required treatment. Onset of atrial fibrillation was preceded by a significant increase in sinus rate and atrial ectopic activity. On multivariate logistic regression, elevated mean postoperative norepinephrine levels (5.78 +/- 2.83 versus 3.57 +/- 1.31 nmol/L; p < 0.0001), increased age (68.9 +/- 5.7 versus 63.8 +/- 8.7 years; p = 0.02), and decreased postoperative magnesium levels (0.79 +/- 0.09 versus 0.83 +/- 0.10 mmol/L; p = 0.02) were independently associated with the occurrence of atrial fibrillation.


CONCLUSIONS
Elevated norepinephrine levels suggest that sympathetic activation may be important in the pathogenesis of atrial fibrillation after coronary artery bypass grafting, and this underlines the importance of beta-adrenoceptor blockade as prophylaxis.
Kalman
J M
JM
Department of Cardiology, Austin Hospital, Melbourne, Australia.
Munawar
M
M
Howes
L G
LG
Louis
W J
WJ
Buxton
B F
BF
Gutteridge
G
G
Tonkin
A M
AM
D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008274:Magnesium / Q000097:blood; D008297:Male; D009638:Norepinephrine / Q000097:blood; D011446:Prospective Studies; D013564:Sympathetic Nervous System / Q000503:physiopathology*
D008274:Magnesium; D009638:Norepinephrine