Differential effects of right atrial ablation sites on vagal modulation of the sinus node during cardioneuroablation

BACKGROUND: Radiofrequency ablation of the superior paraseptal ganglionated plexus attenuates vagal modulation of the sinus node (SAN). Ablation from the right-atrium aspect can achieve a sufficient effect. In a randomized study, we investigated the ablation effects of an anatomically prespecified right atrial linear lesion. METHODS: Twenty patients (age 48 ± 13 years, 70% male) with recurrent reflex cardioinhibitory syncope or symptomatic sinus bradycardia underwent cardioneuroablation. A linear lesion consisting of six equidistantly spaced radiofrequency applications (30 W, 30 s, 20 mL/min) fully covering the posteroseptal quadrant of the superior vena cava (SVC) ostium. Patients were randomly assigned (1:1) to mutually opposite directions of lesion creation: posterior-to-septal (Group 1) or septal-to-posterior (Group 2). Sinus rate and SAN responses to extracardiac vagus nerve stimulation (ECVS) were recorded at baseline and after each radiofrequency energy delivery. RESULTS: As expected, the complete lesion set in the total cohort significantly increased sinus rate (from 60 ± 10 to 80 ± 14 bpm; +35%; P < 0.0001) and reduced ECVS-induced sinus arrest (from 8.3 ± 1.7 to 2.2 ± 1.9 s; -74%; P < 0.0001). The most notable difference between the study groups was observed after performing the initial three lesions. Group 1 showed greater sinus rate acceleration (from 58 ± 9 to 80 ± 16 bpm; +39%; P < 0.001) than Group 2 (from 62 ± 10 to 72 ± 8 bpm; +18%; P < 0.01); P < 0.05 for between-group difference, and a more pronounced reduction in ECVS-induced sinus arrest (from 7.8 ± 1.4 to 1.4 ± 0.6 s; -82%; P < 0.0001) compared to Group 2 (from 8.9 ± 1.9 to 5.7 ± 3.0 s; -39%; P < 0.001); P < 0.0001 for between-group difference. CONCLUSIONS: Ablation of the posteroseptal quadrant of the SVC ostium significantly modified the vagal input to the sinoatrial node. Lesions targeting the posterior area produced more potent effects than those targeting the septal area.