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

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.MethodsOnce such an arrhythmia was detected, continuous ECG monitoring was begun. THEO was then administered i.v. at a rate of 100mg/min until the arrhythmia resolved or a maximum of 250mg THEO was infused. Patients were then monitored for 24 hours for recurrent arrhythmias.ResultsBradyarrhythmias 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±57mg). No recurrent arrhythmia occurred in the follow-up period.ConclusionsMany 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

Mechanisms of ranolazine's dual protection against atrial and ventricular fibrillation

Coronary artery disease and heart failure carry concurrent risk for atrial fibrillation and life-threatening ventricular arrhythmias. We review evidence indicating that at therapeutic concentrations, ranolazine has potential for dual suppression of these arrhythmias. Mechanisms and clinical implications are discussed