Ablation end-point testing not reliable
HAMBURG, GERMANY. It is common practice for electrophysiologists doing pulmonary vein isolations (PVIs) to check the quality of their work by using burst pacing to try to induce atrial fibrillation, or other atrial tachycardias, after the completion of the ablation. If atrial tachycardias are not inducible, the procedure is often considered complete and successful. German researchers now report that post-procedural non-inducibility is in no way a reliable indication of long-term success (avoidance of future atrial tachyarrhythmias).

The study included 60 patients (45 men and 15 women) with paroxysmal AF. The majority (85%) had no underlying structural heart disease, but 33% had a history of hypertension. The patients all underwent a PVI using electroanatomical mapping (CARTO, Pappone method) to create two continuous lesion circles (CCLs) around the right and left pulmonary veins. The completeness of electrical isolation was checked with two Lasso catheters within the ipsilateral (same side) pulmonary veins at least 30 minutes after completion of the ablation.

Atrial arrhythmia inducibility was then evaluated using 10-second burst pacing from the coronary sinus. Seventeen (28%) of the 60 patients (group II) developed sustained atrial tachyarrhythmias (AF in 8 patients, common-type atrial flutter in 6 patients, and left macro re-entrant atrial tachycardia in 3 patients). The remaining 43 patients (72%) did not develop tachyarrhythmias after burst pacing (group I). The researchers observed that the area encircled by the CCLs was significantly smaller in group II than in group I. There was also a trend for group II members to have a larger left atrial volume and area than found among group I members.

After an average follow-up of 16 months, 18 of the 43 patients (42%) in group I had experienced one or more episodes of atrial tachycardia (13 with recurrent AF and 5 with new atrial tachycardia with stable cycle length). In group II, 7 of 17 patients (41%) experienced atrial tachycardia (2 with recurrent AF and 5 with new atrial tachycardia with stable cycle length). All 25 patients with recurrent tachycardia underwent a repeat procedure and all showed signs of recovered electrical conduction between the pulmonary veins and the left atrium. Following the repeat procedure, 91% of group I and 94% of group II remained in stable sinus rhythm during the subsequent follow-up period of 21 months.

The researchers conclude that non-inducibility of post-procedural atrial tachyarrhythmia does not predict long-term success in paroxysmal afibbers having undergone a PVI. They also conclude that inducibility is associated with smaller isolated areas around the pulmonary veins.

Satomi, K, et al. Inducibility of atrial tachyarrhythmias after circumferential pulmonary vein isolation in patients with paroxysmal atrial fibrillation: clinical predictor and outcome during follow-up. Europace, Vol. 10, 2008, pp. 949-54

Editor's comment: It is interesting that the initial (first procedure) success rate was only about 58%, thus indicating that about half of all afibbers undergoing a PVI can count on needing a "touch-up" procedure before they are cured. It is also of interest that the immediate success rate as indicated by post-procedural non-inducibility is not a measure of long-term success. This should be kept in mind when evaluating trials of new catheters and robot-assisted ablation systems since such trials often equate success with lack of conduction or inducibility immediately following the procedure.