Value of High-output Pace-mapping of the Right Phrenic Nerve for Enabling Safe Radiofrequency Ablation of Atrial Fibrillation: Insights from Three-dimensional CT Segmentation.

BACKGROUND

Right phrenic nerve (RPN) injury is a disabling but uncommon complication of atrial fibrillation (AF) radiofrequency ablation. Pace-mapping is widely used to infer RPN's course, for limiting the risk of palsy by avoiding ablation at capture sites. However, information is lacking regarding the distance between the endocardial sites of capture and the actual anatomic RPN location.

OBJECTIVE

To determine the distance between endocardial sites of capture and anatomic CT location of the RPN, depending on the capture threshold.

METHODS

In consecutive patients undergoing AF radiofrequency ablation, we defined the course of the RPN on the electroanatomical map with high-output pacing at up to 50mA/2ms, and assessed RPN capture threshold (RPN-t). The true anatomic course of the RPN was delineated and segmented using CT scan, then merged with the electroanatomical map. The distance between pacing sites and the RPN was assessed.

RESULTS

In 45 patients, 1033 pacing sites were analyzed. Distances from pacing sites to RPN ranged from 7.5±3.0mm (min 1) when RPN-t was ≤10mA, to 19.2±6.5mm (min 9.4) in cases of non-capture at 50mA. A distance to the phrenic nerve > 10mm was predicted by RPN-t with a ROC curve area of 0.846 [0.821-0.870] (p<0.001), with Se=80.8% and Sp=77.5% if RPN-t >20mA, Se=68.0% and Sp=91.6% if RPN-t >30mA, and Se=42.4% and Sp=97.6% if non-capture at 50mA.

CONCLUSION

This data emphasize the utility of high output pace-mapping of the RPN. Non-capture at 50mA/2ms demonstrated very high specificity for predicting a distance to the RPN >10mm, ensuring safe radiofrequency delivery.

Informations de copyright

© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.