Trial: Adenosine-insensitive focal atrial tachycardia: evidence for de novo micro-re-entry in the human atrium

Authors: Markowitz SM, Nemirovksy D, Stein KM, Mittal S, Iwai S, Shah BK, Dobesh DP, Lerman BB.

Reference: J Am Coll Cardiol. 2007 Mar 27;49(12):1324-33.

Purpose: To define the entity and mechanism of adenosine-insensitive focal atrial tachycardia (AT).

Number of Patients: 82 consecutive patients, with 85 focal ATs; 6 tachycardias were insensitive to adenosine (8%)

Number of Centers: 1

Design: Case series

Authors Conclusion: The characteristics of adenosine-insensitive focal AT differ from adenosine-sensitive AT and are consistent with small re-entrant circuits. The adenosine-insensitive ATs arose near the pulmonary vein and from the right atrium.  Electrograms at the site of origin for adenosine-insensitive AT were highly fractionated, with longer duration and lower amplitudes compared with AT that terminated or was transiently suppressed.  In 3 adenosine-insensitive ATs, entrainment was demonstrated with post-pacing intervals equivalent to the tachycardia cycle length.  Data provided evidence that focal re-entry is a mechanism of AT and has an electropharmacological profile that differs from AT due to automaticity and triggered activity.

Key words: Atrial tachyarrhythmia, ablation

Comment: These interesting findings suggest small re-entrant circuits with dimensions below the resolution of electroanatomical mapping systems. 

Ongoing Related Studies:

1. Radiofrequency Ablatiion of Actopic Atrial Tachycardia

Summary written by Andrea Russo, MD