An approach to left septal slow pathway ablation.

BACKGROUND

Slow pathway ablation or modification eliminates typical atrioventricular nodal re-entrant tachycardia (AVNRT), but in less than 5% of patients cannot be accomplished from the right side.

METHODS

Consecutive, consenting patients (n = 221), aged 37 ± 7 years, 177 women, with slow-fast AVNRT, underwent slow pathway ablation. Mapping was restricted to the inferior part of the triangle of Koch, and end-points of ablation were induction of a junctional rhythm with retrograde atrial conduction and non-inducibility of AVNRT. Unsuccessful cases were ablated via a transeptal approach from the left septum with the aid of a left-sided His recording electrode.

RESULTS

Right-sided ablation was successful in 217 of 221 cases. In four patients (1.8%), left-sided ablation was necessary. Procedure, fluoroscopy times, and number of lesions were 105 min (82.4-135) vs. 65 min (60-90) (p = 0.013), 31.9 (23.9-34.3) vs. 9.6 (6.2-14.2) min (p = 0.001), and seven (5.5-7.8) vs. four (4-5; p = 0.004) for left- vs. right-sided procedures, respectively. During a follow-up period of 1-3 years, three patients (1.3%) in the right group had AVNRT recurrence. All had residual dual pathway physiology following ablation, while only 20.3% of patients without AVNRT had residual dual AV nodal conduction (p < 0.001). No conduction disturbances were seen. In the left-sided ablation group, no AVNRT recurrences or AV block were seen.

CONCLUSIONS

Ablation with the protocol described offers a high success rate with an extremely low risk of AV block when left-sided ablation is necessary in patients with typical AVNRT who have failed a right-sided approach.