Catheter ablation of non-sustained focal right atrial tachycardia guided by virtual non-contact electrograms

Abstract

Conventional mapping and catheter ablation of non-sustained focal atrial tachycardia (AT) can be challenging and time consuming. We examined the characteristics and clinical outcomes after catheter ablation of recurrent, sustained AT presenting as non-sustained tachycardia during electrophysiological studies (EPSs), using a non-contact mapping system. In 9 of 88 consecutive patients undergoing ablation of sustained right AT, the tachycardia was non-sustained during EPSs, precluding conventional mapping. We used a non-contact system to map and guide the catheter ablation of brief induced episodes of AT. Atrial tachycardia originated in the crista terminalis (CT) in three patients, tricuspid annulus (TA) in four, posterior right atrium (RA) in one, and mid cavo-tricuspid isthmus in one patient. A QS morphology of the earliest virtual unipolar electrogram was systematically found at the site of successful catheter ablation. The breakout sites were near the CT in six, TA in three, posterior RA in one and anterior RA in one patient. In two patients, two separate breakout sites were identified. All AT (i) were focal and (ii) propagated preferentially to the breakout site(s) before depolarizing the atria. A mean of 5 ± 2 applications of radiofrequency energy was delivered without complications. Procedural duration and fluoroscopic exposure with the non-contact mapping system were 44 and 12 min, respectively. Over a follow-up of 16 ± 11 months, eight of nine patients remained asymptomatic, while in one patient a 'novel' AT emerged during follow-up. Catheter ablation of non-sustained AT, using a non-contact mapping system, was safe and eliminated sustained AT.