Role of Adenosine/ATP Test in Supraventricular Tachycardia

Non-invasive diagnosis of dual AV node physiology (DAVNP) in patients with AV nodal reentrant tachycardia by administration of ATP or adenosine has been reported by different authors4,5. Though many of the studies were using incremental dosage, single dose tests with ATP6 and adenosine7 have also been useful in the diagnosis of DAVNP. The test is useful in sinus rhythm to establish the presence of DAVNP. DAVNP is considered to be present when at least one of the following events occur following ATP injection: 1) PR interval increases or decreases by >50 ms in 2 consecutive sinus beats; 2) an AV nodal echo beat is observed; 3) AVNRT develops. In this issue of the Journal, Belhassen et al8 report that DAVNP is present in a relatively high proportion (36.5%) of patients following termination of AVNRT with ATP but is much less frequent (5.5%) in control patients. In addition, they show that the occurrence of DAVNP following the administration of ATP in sinus rhythm is a good predictor of its occurrence after termination of AVNRT with ATP. Thus, findings at termination of tachycardia by ATP may be useful in the noninvasive diagnosis of the mechanism of a paroxysmal supraventricular tachycardia.