Slow/fast atrioventricular nodal reentrant tachycardia catheter ablation guided by atrial resetting: The new insight.

BACKGROUND

Atrial resetting can be used to discern the anterograde pathway in slow/fast atrioventricular nodal reentrant tachycardia (AVNRT).

OBJECTIVE

We aimed to assess the prevalence of right inferior extension (RIE) and left extension (LE) and the potential impact on the ablation approach.

METHODS

During the electrophysiologic study of patients with slow/fast AVNRT, a decremental supraventricular extrastimulus was delivered within the vulnerability window of the tachycardia cycle at 2 distinct sites: the inferoparaseptal area of the Koch triangle (near the RIE) and the proximal few centimeters of the coronary sinus (near the LE). The site with the latest extrastimulus (longest H-Stim) that could reset the tachycardia was defined as the site of the anterograde slow pathway.

RESULTS

Thirty-six patients were enrolled during a 1-year period. Resetting could not be performed in 10 patients (28%) because of nonsustained tachycardia and in 1 patient because of failed atrial capture. Of the remaining 25 patients (69%), 18 (72%) had the best resetting from the RIE, 5 (20%) had the best resetting from the LE, and 2 (8%) had 2 alternating AVNRTs. The mean H-Stim value in the RIE position was longer when resetting favored RIE compared with LE (46 ± 13 ms vs 16 ± 21 ms; P < .001); a similar pattern was observed in the LE position (59 ± 20 ms vs 15 ± 18 ms; P < .001). Ablation of the left inferior extension could be performed from the right side but significantly closer to the His bundle compared with the RIE (9.6 ± 3 mm vs 18.5 ± 4 mm; P < .001).

CONCLUSION

LE AVNRT is a common finding and can be ablated by a right-sided approach in most cases.