Upper common pathways analysis using late atrial premature depolarization in atrioventricular nodal reentry tachycardia

Background Anatomical and electrophysiological findings suggest the actual circuit of atrioventricular nodal reentrant tachycardia (AVNRT) involves the perinodal atrium. However, occasional instances where the atrium is dissociated from AVNRT have led to the concept of upper common pathways (UCP). Objective We aimed to assess the prevalence of UCP in AVNRT using a late atrial premature depolarization (LAPD) maneuver. Methods Patients who were diagnosed with typical AVNRT by electrophysiologic studies were enrolled. To evaluate the presence of UCP, a LAPD was given at the coronary sinus ostium (osCS) during AVNRT and then pacing was repeated incrementally every 10 ms. Electrograms in the earliest retrograde atrial activation site (ERAS) near the proximal His was mapped and recorded during the pacing. Results were interpreted as i) absence of UCP, a LAPD from osCS can reset the tachycardia without depolarizing the ERAS; ii) presence of UCP, a LAPD from osCS can depolarize the ERAS without resetting the tachycardia; and iii) indeterminate, a LAPD from osCS either resets the ERAS and tachycardia simultaneously or does not reset both. Results The LAPD maneuver was performed in 126 patients with AVNRT. The results demonstrated an absence of UCP in 121 (96.0%) patients, a presence of UCP in 3 (2.4%) patients and indeterminate in 2 (1.6%) patients. Conclusions The LAPD maneuver revealed that the presence of UCP is indicated in only rare cases of AVNRT. In the majority of AVNRT cases, the atrium was involved in the reentry circuit.