Head up tilt test response patterns in patients undergoing cardioneuroablation
Authors: Viveros D , Penela D , Marti-Almor J , Soto-Iglesias D , Falasconi G , Alderete J , Bellido A , Franco P , Francia P , Ordonez A , Ortiz-Perez J T , Berruezo A 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Vasovagal syncope (VVS) is the most common cause of transient loss of consciousness. It severely affects quality of life and can often lead to severe trauma and fatal accidents. Effective treatment of some of these patients can be obtained with cardioneuroablation (CNA). Head-up tilt test (HUT) plays a major role during the evaluation of syncope patients and helps to differentiate syncope subtypes. Data on the HUT response patterns and its usefulness for the recommendation of CNA and the evaluation of the results is lacking.

Purpose
To assess HUT response patterns before and after CNA.

Methods
We included patients with repetitive episodes or considered clinically relevant episodes of vasovagal syncope in the previous 6 months and symptomatic patients with documentation of functional sinus bradycardia or functional AV node block. Before performing CNA, all patients underwent a comprehensive baseline evaluation to analyze sinus node and AV node function. CNA was considered in those patients in whom intrinsic sinus node or AV node disease has been excluded in the electrophysiological study (response to atropine was also assessed), had a VASIS type 2A, 2B or type 1 (mixed) response to the HUT and provided signed informed consent. CNA was performed under general anesthesia and ablation strategy was based on presumed anatomical localization of GP. Follow-up of these patients was performed in the outpatient clinic with scheduled visits at 1, 6 and 12 months including 24-hour Holter monitoring. A control HUT was performed at 3 months.

Results
We included 36 patients. 22 males (61.1%), mean age 51 (18-82 years). The average number of syncope events per year per patient prior to the procedure was 5 ±3. The mean HR on Holter Pre CNA was 65 ± 12 and 72 ± 9 post CNA. Of the HUT, 9 (25%) had mixed type response; 9 (25%) cardioinhibitory type 2A and 18 (50%) cardioinhibitory type 2B. The response in type 2B was sinus arrest in 12 (33.3%), AV block in 5 (13.9%) and both in 1 (2.8%) patient. During a mean of 9 ±4 months follow-up, only 3 patients had a syncope recurrence. At the three-month HUT we observed complete elimination of the cardioinhibitory component present prior to CNA in 34 (94.4%) patients. During the HUT, 18 (50%) had no syncope whereas the remaining 17 had HUT-induced syncope. In 16 (44.4%) of them due to vasodepressor mechanism and only 1 due to cardioinhibitory type 2A response (Figure 1). This patient also had a syncopal recurrence in the follow up. We did not perform the control HUT in 1 patient because of an early recurrence and the patient decided to undergo a pacemaker implantation. We had another recurrence at 11 months post CNA in a patient in whom the control tilt test was negative. The syncope-free survival curve can be seen in Figure 2.

Conclusions
CNA changes the response pattern of the HUT by eliminating the cardioinhibitory component and can be useful in the evaluation of the long-term CNA outcomes.