Aims: To investigate the utility of adenosine administration to test the durability of cavotricuspid isthmus (CTI) block after radiofrequency (RF) catheter ablation for typical atrial flutter.
Methods: Adenosine 10 mg was administered by bolus injection through a femoral sheath at 5 minutes after apparent completion of CTI ablation in consecutive patients, and its effect on CTI conduction was recorded. Conduction in both directions across the CTI was tested repeatedly until 20 minutes after the last energy delivery.
Results: Among 132 patients treated with a Blazer 10 mm (n=126) or 8 mm (n=6) ablation catheter, bidirectional block of the CTI was achieved in all cases. Adenosine administration was followed by a transient recurrence of conduction in three cases (2.3%); in all of these, a persistent recurrence of CTI conduction was observed within the waiting period. Persistent recurrence of CTI conduction occurred within the waiting period in three patients (92.3%) whose adenosine test had been negative. In all cases, further RF delivery achieved CTI block that persisted to the end of a 20-minute waiting period. During 38 months of follow-up, 131 patients (99.2%) remained free of clinical recurrence of typical flutter.
Conclusion: Administration of adenosine 10 mg at 5 minutes after RF delivery reveals latent conduction in the CTI in some but not all cases that are revealed by a 20-minute wait. At this dosage and at this time-point, adenosine testing is not an adequate substitute for a waiting period.