Department of Cardiology, Pasteur University Hospital, 30 avenue de la Voie Romaine, 06000 Nice, France.
Department of Cardiac Electrophysiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
Europace. 2024 Aug 3;26(8). doi: 10.1093/europace/euae207.
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. We aimed at determining the distance between endocardial sites of capture and anatomic CT location of the RPN, depending on the capture threshold.
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 50 mA/2 ms, 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. In 45 patients, 1033 pacing sites were analysed. Distances from pacing sites to RPN ranged from 7.5 ± 3.0 mm (min 1) when RPN-t was ≤10 mA to 19.2 ± 6.5 mm (min 9.4) in cases of non-capture at 50 mA. A distance to the phrenic nerve > 10 mm 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 > 20 mA, Se = 68.0% and Sp = 91.6% if RPN-t > 30 mA, and Se = 42.4% and Sp = 97.6% if non-capture at 50 mA.
These data emphasize the utility of high-output pace-mapping of the RPN. Non-capture at 50 mA/2 ms demonstrated very high specificity for predicting a distance to the RPN > 10 mm, ensuring safe radiofrequency delivery.
右侧膈神经（RPN）损伤是心房颤动（AF）射频消融的一种致残但罕见的并发症。起搏标测广泛用于推断 RPN 的走行，通过避免在捕获部位进行消融来限制瘫痪的风险。然而，关于心内膜捕获部位与实际解剖 RPN 位置之间的距离，信息仍然缺乏。我们旨在确定心内膜捕获部位与 RPN 的解剖 CT 位置之间的距离，取决于捕获阈值。
在连续接受 AF 射频消融的患者中，我们使用高达 50mA/2ms 的高输出起搏在心电解剖图上定义 RPN 的走行，并评估 RPN 捕获阈值（RPN-t）。使用 CT 扫描描绘和分割 RPN 的真实解剖走行，然后与心电解剖图融合。评估起搏部位与 RPN 之间的距离。在 45 例患者中，分析了 1033 个起搏部位。当 RPN-t≤10mA 时，起搏部位到 RPN 的距离为 7.5±3.0mm（最小值 1），而在 50mA 时非捕获时为 19.2±6.5mm（最小值 9.4）。ROC 曲线面积为 0.846[0.821-0.870]（P<0.001），RPN-t>10mA 时 Se=80.8%，Sp=77.5%，RPN-t>30mA 时 Se=68.0%，Sp=91.6%，50mA 时非捕获时 Se=42.4%，Sp=97.6%，提示与 RPN 之间的距离>10mm。
这些数据强调了 RPN 高输出起搏标测的实用性。50mA/2ms 时的非捕获对预测 RPN 距离>10mm 具有非常高的特异性，可确保安全的射频输送。
