Comparison of adenosine and verapamil for termination of paroxysmal junctional tachycardia.

The effects of intravenous adenosine and intravenous verapamil on paroxysmal junctional tachycardia were compared in 20 patients undergoing invasive cardiac electrophysiologic study. In 13 patients the diagnosis was of a reentrant tachycardia using an extranodal accessory connection (atrioventricular [AV] reentrant tachycardia); 5 of these patients had overt preexcitation in sinus rhythm, 4 had concealed accessory connections and 4 had latent or intermittent preexcitation. In 7 patients the diagnosis was of an AV nodal reentrant tachycardia. Administration of adenosine resulted in termination of tachycardia in all 20 patients at a mean dose of 0.125 mg/kg (range 0.05 to 0.20). Although termination of tachycardia was frequently accompanied by atrial and ventricular premature complexes, no significant arrhythmias were observed after conversion. Administration of verapamil (0.145 mg/kg) resulted in termination of tachycardia in 19 of 20 patients but was followed by symptomatic arrhythmias in 2: preexcited atrial flutter in 1 patient and preexcited atrial tachycardia in another. Latent or intermittent preexcitation was unmasked in 4 of 4 patients immediately after termination of tachycardia by adenosine. Termination of tachycardia by verapamil revealed preexcitation in only 1 of these 4 patients. Analysis of results in terms of successful termination of tachycardia, absence of significant arrhythmias after conversion and unmasking of latent or intermittent preexcitation reveals that adenosine therapy was satisfactory in all 20 patients, whereas verapamil was satisfactory in only 14 of the 20 patients (p less than 0.05). All 6 of the patients with unsatisfactory responses to verapamil had AV reentrant tachycardia. These results suggest that adenosine has particular advantages over verapamil as acute treatment for patients presenting with an AV reentrant tachycardia.