Right atrial tachycardias related to regions of low-voltage myocardium in patients without prior cardiac surgery: catheter ablation and follow-up results.

Aims: There are only few descriptions of patients without prior cardiac surgery in whom a large low-voltage zone (LVZ) or scar is the electrophysiological substrate for various atrial tachycardias. We describe the electrophysiological and electroanatomic characteristics of unusual macroreentrant atrial tachycardias (MRATs) in seven patients with spontaneous right atrial (RA) scarring and present long-term follow-up results.

Methods And Results: In 7 of 326 patients with MRAT treated with radiofrequency ablation we detected regions of RA spontaneous LVZ or scarring during conventional mapping of the arrhythmia. They underwent electroanatomic mapping and catheter ablation of the spontaneous and further induced arrhythmias with a long-term follow-up. A total of 17 different atrial tachycardias were observed with typical atrial flutter in four patients. In five patients a LVZ was found in the RA free wall and two patients had a septal scar. Stable circuits were around the scar or LVZ in four patients and through a 'channel' within the scar in two. Radiofrequency ablation sites included the cavotricuspid isthmus for typical atrial flutter, between the inferior vena cava and scar, a channel in the scar or the left atrial (LA) mitral isthmus. During follow-up of 34 ± 5 months, four patients were free from atrial tachycardias. Both patients with a septal RA scar developed LA tachycardias, requiring further catheter ablation. One patient presented with a novel type of atypical scar-related RA flutter.

Conclusion: Mapping and ablation of scar-related RA tachycardias is an effective treatment but does not preclude the development of further tachycardias, some of them arising from the LA during long-term follow-up.