Trial to evaluate the management of paroxysmal supraventricular tachycardia during an electrophysiology study with tecadenoson

Background - Tecadenoson is a potent selective A(1)- adenosine receptor agonist with a dose- dependent negative dromotropic effect on the AV node. Tecadenoson terminates induced paroxysmal supraventricular tachycardia ( PSVT) without the clinically significant side effects caused by stimulation of other adenosine receptors. This trial was designed to determine a safe and effective tecadenoson bolus for termination of electrophysiologically induced PSVT. Methods and Results - Patients with a history of symptomatic PSVT and inducible PSVT at the time of a clinically indicated electrophysiology study were randomized into a multicenter, double- blind, placebo- controlled trial. Five 2- dose tecadenoson bolus regimens were evaluated versus placebo ( 75/ 150, 150/ 300, 300/ 600, 450/ 900, 900 mu g/ 900 mu g). The second bolus was administered only if PSVT persisted for 1 minute after the first bolus. Each tecadenoson regimen resulted in a significant therapeutic conversion rate compared with placebo ( range, 50.0% to 90.3%, analysis of all patients dosed; n = 181; P < 0.0005). Conversion by the first bolus was dose related ( range: placebo, 3.3% to 86.7% for 900 mu g/ 900 mu g). Time to conversion was dose dependent, with a median time of < 1 minute for the 3 highest dose regimens. Postconversion arrhythmias were transient, requiring no additional treatment in 4 regimens ( including placebo). Transient second- and third- degree heart block occurred at higher doses ( 300/ 600, 450/ 900, 900 mu g/ 900 mu g) and was supported with backup pacing when needed. No effect on blood pressure was observed. Ten patients with a history of asthma or chronic obstructive pulmonary disease tolerated tecadenoson without bronchospasm. Conclusions - We identified an optimal tecadenoson regimen ( 300 mu g/ 600 mu g) that effectively and rapidly converted 90% ( 28 of 31) of PSVT patients to normal sinus rhythm with no significant adverse effects.