Adenosine preconditioning reduces both pre and postischemic arrhythmias in human myocardium

Introduction. Consistently, clinical series record supraventricular tachyarrhythmias in approximately 30% of patients following coronary artery bypass surgery (CABG). Ischemic preconditioning and adenosine preconditioning (Ado-PC) decrease postischemia/ reperfusion (IIR) myocardial stunning, infarct size, and pharmacologically induced arrhythmias in all species including man. We hypothesized that adenosine preconditioning would decrease spontaneous pre- and postischemic atrial arrhythmias in human myocardium, The purposes of this study were to determine the effect of in vivo and in vitro Ado-PC on atrial arrhythmias, Methods. Human atrial trabeculae were harvested from CABG patients, placed in organ baths, and paced (1 Hz). Developed force (DF) was recorded during simulated YR (30/45 min). Prior to IIR, trabeculae were treated with Ado (125 mu M) for 5 min tin vitro), or patients were treated with Ado (12 mg iv) 5 min tin vivo) prior to harvest of trabeculae. Contraction frequency >4 Hz (defined as atrial tachyarrhythmias) was recorded in all groups pre- and postischemia. Results. Control trabeculae exhibited increased tachyarrhythmias pre- and postischemia. In vivo and in vitro Ado-PC suppressed both pre- and postischemic arrhythmias. Conclusions. Adenosine preconditioning suppresses the frequency of pre- and postischemic tachyarrhythmias against an ischemia/reperfusion insult in human myocardium. This antiarrhythmic effect occurs with both in vitro and in vivo administration of adenosine. Preconditioning with adenosine prior to elective ischemia/reperfusion is a prmising strategy of reducing spontaneous atrial arrhythmias in patients undergoing myocardial revascularization. (C) 2000 Academic Press.