Impact of Right Pulmonary Vein Anatomical Variations on Phrenic Nerve Trajectory and Pulmonary Vein Isolation Strategy: Pre-Procedural Imaging and 3D Mapping Insights.

Background: Predicting phrenic nerve (PN) location based on right pulmonary vein (RPV) anatomy using pre-ablation imaging may help avoid PN injury.

Objective: To determine the relationship between RPV anatomical variations and PN trajectory.

Methods: 103 consecutive patients with pre-ablation CT or MRI had RPV anatomy identified as: typical with separate RSPV and RIPV with distal branching versus right middle PV (RMPV) or early branching of RSPV. PN location was identified using high-output pacing (50mA x 2ms) over three contiguous RPV ostial and paraseptal antral zones: right superior PV (RSPV), RPV carina, and right inferior PV (RIPV). The relationship between anatomic variations and PN trajectory with need to adjust planned ablation lines to more distal antral position (> additional 10 mm from ostium) was determined.

Results: RSPV early branching occurred in 24%, and RMPV in 21% with anatomic variations more frequent in women (65% vs. 38%, p=0.01). PN capture extending to RIPV antrum was significantly more common in patients with RMPV (59.1%, PR=10.3; 95% CI: 2.5-43.2) or early branching of RSPV (64%, PR=10.9; 95% CI: 2.7-44) compared to typical anatomy (3.6%). Antral ablation line adjustments to avoid PN injury were required in 28% of patients, more frequently in those with RMPV (50%, PR=5.6; 95% CI: 2-15.7) or early branching (56%, PR=5.2; 95% CI: 1.3-15.3) compared to typical anatomy (7.1%).

Conclusions: RMPV or early branching of RSPV increases likelihood of PN capture in the RIPV proximal antrum by tenfold and requires a more distal antral ablation line to avoid phrenic nerve injury.