Posterior (“atypical”) atrioventricular junctional reentrant tachycardia

The aim of this study was to characterize a relatively rare type of atrioventricular (AV) junctional reentrant tachycardia (AVJRT). Posterior AVJRT is a type of AV nodal tachycardia in which the site of earliest atrial activation is posterior to the AV node near the coronary sinus orifice. The mechanism of this tachycardia is not well understood. The characteristics of posterior AVJRT (n = 15) were compared with those of anterior (“common”) AVJRT (n =146) and supraventricular tachycardia using single posterior septal accessory pathways (n = 13). During posterior AVJRT, the AH interval was longer than the, retrograde conduction time (His to earliest atrial activity) in 11 cases (73%), indicating that these tachycardias were not fast-slow types of AVJRT. The mean ventriculoatrial (VA) interval in posterior AVJRT (93 ± 41 ms) was longer than in anterior AVJRT (11 ± 20 ms; p 80 ms before the His deflection. Anterograde conduction was similar in the posted or and anterior AVJRT groups. During ventricular pacing, the VA interval was longer in patients with posterior AVJRT (287 ± 113 ms) than in those with anterior AVJRT (199 ± 48 ms; p