Role of endogenous adenosine in atrial fibrillation after coronary artery bypass graft.
BACKGROUND
Atrial fibrillation (AF) is the most common complication following coronary artery bypass graft (CABG). The mechanism of AF after CABG is not well defined; however, it is suggested that endogenous adenosine, released in response to tissue hypoxia, may play a mechanistic role in these arrhythmias.


OBJECTIVE
The purpose of this study was to examine whether intravenous theophylline, via adenosine A1 receptor antagonism, would correct or modify new-onset early (<48 h post CABG) atrial fibrillation in patients post CABG, and thereby implicate endogenous adenosine as an inciting agent.


METHODS
A prospective double-blind, placebo-controlled study design was applied to 385 consecutive patients with coronary artery disease who had undergone CABG. Any patient who developed AF within 48 h of the operative procedure was randomly assigned to receive 5 mg/kg of intravenous theophylline (Group A) or matched intravenous placebo (Group B). The patients who converted to sinus rhythm within 15 min of drug administration were accepted as showing positive responses.


RESULTS
Thirty patients comprised the study group. In Group A, 8 of the 15 patients (53%) converted from AF to sinus rhythm within 15 min of theophylline administration. One patient who converted to sinus rhythm 20 min after theophylline administration was accepted as showing a negative response. In the placebo-treated group, no patient converted to sinus rhythm within 15 min (p<0.007 compared with Group A).


CONCLUSIONS
The mechanism of AF after CABG is not well defined and is probably multifactorial. However, this study demonstrated that antagonism of the adenosine A1 receptor can promptly convert many of these patients back to sinus rhythm, and thereby implicates endogenously released adenosine in a mechanistic role for inciting early (<48 h) post-CABG AF.
Yavuz
Turhan
T
University of Suleyman Demirel, School of Medicine, Department of Cardiovascular Surgery, Isparta, Turkey.
Bertolet
Barry
B
Bebooul
Yavuz
Y
Tunerir
Bulent
B
Aslan
Recep
R
Ocal
Ahmet
A
Ybribim
Erdooan
E
Kutsal
Ali
A
D000241:Adenosine / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004311:Double-Blind Method; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage* / Q000493:pharmacokinetics; D011446:Prospective Studies; D013806:Theophylline / Q000008:administration & dosage* / Q000493:pharmacokinetics
D010726:Phosphodiesterase Inhibitors; D013806:Theophylline; D000241:Adenosine