805-1 Theophylline Reverses Myocardial Infarction-Related Brady and Tachy Arrhythmias: Role of Adenosine

Abstract

Brady and tachyarrhythmias often complicate the early management of acute myocardial infarction (MI). Endogenously released adenosine (ADO) from ischemic cardiac cells has been proposed as a potential mediator of these arrhythmias. In order to test this hypothesis, theophylline (THEO), a competitive ADO receptor antagonist, was administered to nine patients who developed sustained or hemodynamically significant brady or tachyarrhythmias immediately following an acute inferior MI. Once such an arrhythmia was detected, continuous ECG monitoring was begun. THEO was then administered i.v. at a rate of 100 mg/min until the arrhythmia resolved or a maximum of 250 mg THEO was infused. Patients were then monitored for 24 hours for recurrent arrhythmias. Bradyarrhythmias were detected in 5 patients (3 with 3° AV block, 2 with 2° AV block). Tachyarrhythmias were detected in four patients (2 with atrial fibrillation, 2 with accelerated idioventricular rhythm). All patients converted to normal sinus rhythm within five minutes of the administration of THEO (178 ± 57 mg). No recurrent arrhythmia occurred in the follow-up period. Many of the brady and tachyarrhythmias which occur early after inferior MI are ADO-mediated. ADO receptor antagonism appears effective in converting these arrhythmias to normal sinus rhythm and may be considered as primary therapy.