(CCSP039) CARDIONEURAL ABLATION FOR REFRACTORY CARDIO-INHIBITORY SYNCOPE

Background: Cardio-inhibitory vasovagal syncope is characterized by prolonged pauses and asystole. These patients are frequently young, experience traumatic syncope, refractory to conservative management, and are referred for pacemaker implantation. Cardioneural ablation (CNA) is a very novel ablation technique to reduce syncope burden and avoid pacemaker implantation. This study aims to demonstrate the feasibility and safety of CNA in patients with high-burden syncope.

METHODS AND RESULTS: Demographic, procedural, and follow-up data was collected prospectively for all patients undergoing CNA between December 2020 to present. Patients were required to have a history of recurrent refractory syncope, where corresponding prolonged pauses were documented by implantable loop recorder (ILR). Under general anesthesia, both left and right atria were mapped. An ablation catheter was then used to identify fragmented signals in anatomical regions consistent with ganglionic plexi (GP). High frequency stimulation (60ms at 20mV for 4 seconds) was delivered at sites of interest in both the left and right atria, and radiofrequency energy delivered to these GP regions. Ablation was performed until loss of positive response to stimulation or when Wenckebach cycle shortening was achieved. All right and left atria GP were targeted. Between December 2020 and May 2023 five patients with medically refractory cardio-inhibitory syncope underwent CNA. All patients had objective adjudication of their outcomes through remote and in-clinic follow-up of their ILRs. Mean age was 29±3 years, with AV block being the predominant indication for CNA. The baseline heart rate was 63.2±10.7bpm and 90±7.1 after ablation. Baseline PR pre 223±23ms and post 186±5.8ms. Mean procedure time was 92.4 ±8 minutes. During a mean follow-up 11.4±10.5 months, there was a substantial reduction in syncopal events, from mean 10.4±3 episodes within the previous year to 0.4±0.5 post CNA. 3 patients had no further pauses or syncopal events, 1 had a recurrence at 7 months, underwent repeat CNA with no further episodes at a further 10 months follow-up, and 1 had only 2 syncopal events, which was a dramatic reduction from nearly daily episodes pre-CNA. There were no procedure related complications.

Conclusion: CNA is a novel technique that may be considered for refractory cardio-inhibitory syncope. A dramatic reduction in documented pauses and syncope burden was noted. Rigorous patient selection with objective follow-up in an experienced center is necessary. To our knowledge, this is the first series of Canadian patients in whom CNA has been performed. Larger studies are required to confirm these findings.