Adenosine facilitates dormant conduction across cavotricuspid isthmus following catheter ablation.

Background: Recurrence of trans-isthmus conduction following catheter ablation of common right atrial flutter (AFL) has been reported to be as high as 15%-31% at 3 months with invasive follow-up. Intravenous adenosine has previously been shown to facilitate acute, transient reconnection of pulmonary veins following catheter ablation of atrial fibrillation.

Objective: To determine whether intravenous adenosine can facilitate dormant trans-isthmus conduction after achieving bidirectional conduction block (BDB) with catheter ablation.

Methods: Thirty-two patients underwent radiofrequency catheter ablation of cavotricuspid isthmus (CTI) for common right AFL at 2 institutions. Once persistent BDB was achieved for 30 minutes and during isoproterenol infusion, 18 mg of intravenous adenosine was injected during coronary sinus pacing. Evidence for transient reconduction across the isthmus was observed. Additional ablation lesions were performed, and adenosine infusion was repeated to reassess for dormant conduction.

Results: Thirty-two (men 81%, hypertension 72%, coronary artery disease 15%, congestive heart failure 25%, diabetes mellitus 30%, left atrial size 42 ± 11 mm, left ventricular ejection fraction 51% ± 10%) patients underwent ablation of CTI. BDB was achieved in 30 of the 32 patients. Following adenosine infusion, transient reconduction was observed in 7 of the 30 patients (23%) for 10-45 seconds. Following additional ablation lesions, persistent BDB could be achieved in all 7 patients without evidence for reconduction with repeat adenosine infusion. During a mean follow-up of 19 ± 12 months, only 1 of 30 patients (3%) had clinical recurrence of AFL. None of the patients with transient reconduction after adenosine developed symptomatic recurrence of AFL.

Conclusions: Adenosine infusion can facilitate dormant conduction across CTI following catheter ablation. Persistent BDB can be achieved with additional ablation. Adenosine challenge with additional ablation may improve long-term clinical outcome.