Pacemaker Implantation Versus Cardioneuroablation for Functional Atrioventricular Block


The TELE-SPACER study is a multicenter, noncommercial, physician-initiated, proof-of-concept, prospective, randomized, controlled, unblinded clinical trial and registry designed to compare two methods of treatment of patients with functional Atrio-Ventricular Block (AVB): the guidelines-recommended elective pacemaker (PM) therapy vs cardiovascular autonomic tests (CAT), electrophysiologic assessment (EPS) with referral to cardioneuroablation (CNA) and reevaluation of indications for PM therapy. The main questions TELE-SPACER aims to answer are: – Can the investigators successfully treat functional AVB without implantable device (PM)? – Can the investigators prove the feasibility and safety and demonstrate non-inferiority of CNA procedure in patients with functional AVB, avoiding long-term permanent pacing, its limitations, complications and costs ? The TELE-SPACER trial will validate the European Society of Cardiology (ESC) recommendations (level C of evidence: expert opinion) for elective PM implantation and will introduce CNA as effective treatment in the functional AVB patient population. Functional AVB – defined as a persistent or paroxysmal AVB with a positive results of atropine test

Full Title of Study: “TELE-monitoring for Standard Pacemaker Implantation or Delayed Pacemaker Implantation After Autonomic/Electrophysiologic Evaluation and Cardioneuroablation for managEment of Functional atrioventriculaR Block – Randomized Controlled Study”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Single (Outcomes Assessor)
  • Study Primary Completion Date: August 31, 2026

Detailed Description

TELE-SPACER trial will enroll a minimum of 100 participants, males and females, 18-75 years old: 1) with indications for elective PM implantation due to atrioventricular block (AVB) according to 2021 ESC guidelines on cardiac pacing; 2) who had positive atropine tests. Participants will be randomized into two groups – either optimized guideline-recommended PM therapy (group A, n=50) or reevaluation for PM therapy after CAT/EPS and experimental procedure CNA (group B, n=50). Participants who will choose to opt-out of randomization will be included in the registry (group C) and will undergo patient-tailored intervention through shared decision-making with a possibility of either PM implantation, CNA or observation only. The registry is expected to include up to 200 participants. Patient enrollment time is anticipated to last 2 years. Recruitment will take place in four study sites, in two distinct phases. First, the investigators will identify potential participants with AVB and a positive atropine test, confirming significant dependence of heart rhythm and conduction on the vagus nerve (hyperactivity of vagus nerve). Their medical records will be analyzed by the Scientific Committee (symptoms evaluation, physical examination, documentation of AVB). In the second phase eligible participants will be invited by the investigator to participate in the trial during medical consultation. After explanations describing the study protocol, including the risk and benefits, they will sign the written informed consent to participate in the study or will choose to opt-out of randomization to be included in the registry only (group C). Informed consent will be obtained only if it is clear that the patient truly understands the nature of the study. Alternatively, the patient will be encouraged to take a copy of the consent form home to contemplate enrolment in the study. Only participants who voluntarily consent will be included. Participants will be able to withdraw at any time without compromising their medical care. Paricipants will be randomized in 1:1 allocation to either group A or group B. Randomization will be performed centrally and assigned automatically to each patient via internet. The randomization list will be blocked per center, with randomly varying block sizes of 2 and 4. The centers will not be aware of the block sizes. The PM implantation and treatment allocation will not be blinded to the patient or follow-up physician. Participants in either arm of the study will be followed-up at regular intervals for a minimum of 12 months. During the 12-month study duration, the use of effective contraception will be recommended for women of child-bearing age. The period of the screening and randomization visit will last from 0 to 7 days, and the qualification for elective PM implantation (group A) or elective loop recorder monitoring/CAT/EPS (group B) and subsequent therapeutic decisions (CNA, DDDR, other treatment based on the test result) from 0 to 4 weeks. Parameter analysis baseline, including ECG telemonitoring, QOL and symptoms, will take place at randomization (0 months), 3, 6 and 12 months. Participants will be assessed using cardiovascular autonomic testing (CAT) with telemedical registration at 6 and 12 months. All measured parameters, as well as demographic and clinical data will be recorded in the study database. Participants in group A (PM, n = 50) will receive care on the basis of the 2021 ESC Guidelines on Cardiac Pacing Recommendations. They will be implanted with PM (DDD pacemaker or its modification as HBP/LBBAP – His-Purkinje or left bundle branch area pacing) and will be monitored with external ECG recorder (certified medical devices of at least class IIa) with telemonitoring. Group B participants (CNA, n = 50) will be implanted with implantable loop recorder (ILR) device (Biotronik, Biomonitor 3m), also with remote tele-monitoring, with the same thresholds for automatic episode recording. As part of telemonitoring system, all participants will receive in the period before the procedure a dedicated telemonitoring kit consisting of a portable ECG device and a tablet with a sim card for network connection. This telemonitoring kit will enable regular self-testing, symptom reporting and interactive, objective telemedicine consultations. Participants will be provided with 24/7 contact with medical staff in the telemonitoring center specialized in cardiac arrhythmias and implantable device monitoring. The major reason for ECG recording is to provide ECG documentation of clinical AVB, as well as monitoring of participants before and after CNA (or PM implantation, if accepted). In case of severe AVB, the emergency system will always be called. Participants in group B will be referred for EPS and ECVS (extracardiac vagal nerve stimulation) with the possibility of simultaneous CNA after exclusion of advanced and occult distal AVBs. Once the effectiveness of the CNA is confirmed, the patient will be further monitored. If CNA is not succesful and/or its immediate effectiveness is not confirmed (meeting the ESC criteria for pacemaker implantation after CNA), the patient will be referred for pacemaker implantation and will cross-over into group A. CNA will be performed in group B under general anesthesia by experienced operators (at least 25 CNA procedures preformed). After EPS, a biatral, binodal, anatomically guided CNA will be performed under ECVS guidance, with a demonstration of the vagal reflex (complete asystole or AVB with atrial pacing) at the onset of the CNA and its complete disappearance after a successful CNA. Additional ablation substrates will also be allowed and performed. Participants included in the registry (group C) will undergo an individually tailored intervention through shared decision making (SDM) with the option of implantation of PM (subgroup CA), CNA (subgroup CB) or observation only (subgroup C0). All participants participating in the study and registry will be asked to complete questionnaires on health-related quality of life (EQ-5D-5L, SF-36), symptoms of bradycardia (VAS), fatigue (MFIS), depression (HADS-M) and sleep (ESS, AIS-8) at 0, 6, 12 months. The safety of the interventions will be assessed on a monthly basis (telemedicine and standard follow-up visits), with monitoring of major adverse cardiovascular events (MACE). All events will be resolved by the Central Investigation Safety Committee, which does not include members of the Investigation Steering Committee.


  • Procedure: Pacemaker implantation
    • Elective pacemaker implantation (DDDR) for functional AVB according to the 2021 ESC Guidelines for Cardiac Pacing
  • Procedure: Cardioneuroablation (CNA)
    • Experimental method; elective implantable loop recorder (ILR) and biatrial, binodal, atomically and electroanatomically guided CNA with extracardiac vagal nerve stimulation (ECVS) prior and after procedure monitoring (disappearance of ECVS-induced AVB with the goal of achieving post-procedure and maintaining a target heart rate > 50 beats per minute). CNA procedure is performed with radio-frequency generators and irrigated catheters and with support of 3D-electroanatomic mapping system. CNA group will receive external ECG recorders. The major reason for external ECG recorders is to provide documentation of clinical AVB, as well as monitoring of patients before and after CNA (or PM implantation, if accepted). In case of severe AVB symptoms always the emergency system will be called.

Arms, Groups and Cohorts

  • Active Comparator: Group A – PACEMAKER
    • Group A, n=50 patients aged 18-75 years with indications for elective PM implantation according to the 2021 ESC guidelines for cardiac pacing due to paroxysmal or persistent AVB with a positive results of atropine test. Group A is early elective pacemaker implantation (PM) strategy in functional AVB.
  • Active Comparator: Group B – CARDIONEUROABLATION
    • Group B, n=50 patients aged 18-75 years with indications for elective PM implantation according to the 2021 ESC guidelines for cardiac pacing due to paroxysmal or persistent AVB with a positive results of atropine test. Group B will undergo strategy of postponed/deferred PM implantation in functional AVB. Patients wil be implanted and monitored with ILR (in case of severe symptomatic AVB always the emergency system will be called). After cardiovascular autonomic testing (CAT), electrophysiological study (EPS), extra cardiac vagal nerve stimulation (ECVS) and cardioneuroablation will be performed. If CNA is succesful, pacemaker implantation will be cancelled. If CNA is unsuccessful, second session of CNA will be planned. In case of inefficient second attempt, patients will be referred for PM implantation. They will cross-over to PACEMAKER arm.

Clinical Trial Outcome Measures

Primary Measures

  • To determine the efficacy of CNA in the treatment of AVB in comparison to PM therapy within 12 months of PM implantation/CNA procedure.
    • Time Frame: 12 months
    • This is objective endpoint examining the onset of AVB episodes after PM/CNA. It will specify the number of pauses > 3.0 s in the ECG external recorder for group B (occurrence of > 1 pause or the need for earlier (0-12 months) PM implantation will be an indicator of the failure of the CNA procedure), assuming the presence of PM stimulation in group A at the level between 93-100% (equates to the continued duration of the AVB treated with PM).

Secondary Measures

  • Occurrence of MACE (major advers cardiac events)
    • Time Frame: at 0, 3, 6, 12 months
    • MACE are defined as peri-procedural and long-term complications: death, stroke, myocardial infarction, pericardial effusion requiring drainage, AVB, venous thrombosis, infection, hemorrhage, hematoma, fistula, pseudoaneurysm, surgical intervention
  • Assessment of the effect of CNA and PM implantation on AVB symptoms based on based on VAS (Visual Analog Scale)
    • Time Frame: 0, 3, 6, 12 months
    • VAS (Visual Analog Scale) indicates the general health status with100 indicating the best health, 0 indicating the worst health status.
  • Assessment of the effect of CNA and PM implantation on health-related quality of life (QOL) based on questionaire EQ-5D-5L
    • Time Frame: 0, 6, 12 months
    • EQ-5D-5L comprises five dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each dimension is scored on a scale of 1-5 ponts, that describes the patient’s health state. The maximum score of 1 indicates the best health state, higher scores indicate more severe or frequent problems.
  • Assessment of the effect of CNA and PM implantation on health-related quality of life (QOL) based on questionaire SF-36
    • Time Frame: 0, 6, 12 months
    • SF-36 questionnaire consists of 36 questions that are distributed across eight scales. Each scale is directly transformed into 0-100 scale. The lower the score the more disability, the higher the score the less disability.
  • Assessment of the effect of CNA and PM implantation on fatique based on Modified Fatigue Impact Scale (MFIS)
    • Time Frame: 0, 6, 12 moths
    • MFIS is a validated, standardized, 21-item questionnaire, which provides an assessment of the effects of fatigue in terms of physical, cognitive, and psychosocial functioning. Total scores range from 0-84. The lower the score the less fatigue, the higher the score the more fatigue impairs physical, cognitive, and psychosocial functioning.
  • Assessment of the effect of CNA and PM implantation on depression/anxiety based on Modified Hospital Anxiety and Depression Scale (HADS-M)
    • Time Frame: 0, 6, 12 months
    • HADS-M is a validated, standardized 16-item questionnaire to evaluate the association between anxiety and depression and the degree of illness acceptance in patients. Total scores range from 0-64. Higher scores indicate a greater degree of anxiety or depression.
  • Assessment of the effect of CNA and PM implantation on sleep disorders based on questionaire Epworth Sleep Scale (ESS)
    • Time Frame: 0, 6, 12 months
    • The ESS score is a standardized, validated 8-item questionnaire (with scores 0-3 each). The total score can range from 0 to 24. The higher the ESS score, the higher that person’s average sleep propensity in daily life.
  • Assessment of the effect of CNA and PM implantation on sleep disorders based on Athens Insomnia Scale-8 (AIS-8)
    • Time Frame: 0, 6, 12 months
    • AIS-8 is a standardized, validated questionnaire assessing 8 factors related to nocturnal sleep and daytime dysfunction, which are rated on a 0-3 scale. The sleep is evaluated from the cumulative score of all factors and reported as an individual’s sleep outcome. Higher score indicates more sleep disturbances.

Participating in This Clinical Trial

Inclusion Criteria

1. Written informed consent to participate in the study 2. Age 18-75 3. Indication (at least one) of the European Society of Cardiology (ESC) for elective pacemaker implantation due to isolated (without sinus node dysfunction and bundle branch block) paroxysmal, persistent or reflex atrioventricular block: 1. Symptomatic first degree AVB (above 300 msec). Class IIaC 2. Symptomatic Mobitz type I second degree AVB. Class IIaC 3. AVB 2:1, even asymptomatic, but not during sleep. Class IIaC 4. Mobitz II type advanced 2nd degree AVB or complete block (3rd degree AVB). Class IC 5. Advanced AVB during AF regardless of symptoms, but not during sleep. Class IC 6. Reflex syncope in patients over 40 years of age with documented pauses within the AVB mechanism, symptomatic (>3 sec) or asymptomatic >6 sec. Class IC 7. Reflex syncope in patients over 40 years of age with documented pauses within AVB mechanism in the course of sick sinus syndrome (CSS). Class IC 8. Reflex syncope in patients over 40 years of age with documented pauses within AVB mechanism during tilt test. Class IC Exclusion Criteria:

1. Implanted pacemaker/ICD/CRT 2. Sinus node dysfunction with indication for pacemaker implantation 3. Planned ablation of the atrioventricular junction 4. Severe prolonged bradycardia in advanced AVB requiring intravenous drugs and temporary pacing 5. Status post cardiac surgery 6. Acute myocardial infarction and heart failure (not related to bradycardia) 7. Status post percutaneous valvular intervention or ablation 8. Acute infection or any other accompanying disease which is contraindication to percutaneous procedures and/or implantation of a pacemaker 9. Pregnancy, nursing or planned pregnancy within 12 months 10. Decompensated chronic diseases (endocrine disorders, electrolyte disorders, etc.) 11. Advanced cardiomyopathies with indication for ICD implantation in primary or secondary prevention of sudden cardiac death (SCD) 12. Advanced ventricular arrhythmias with indication for ICD implantation in primary or secondary prevention of SCD 13. Persistent right or left bundle branch block 14. Musculoskeletal diseases with separate indications for pacemaker implantation 15. Contraindications to the procedures used in the study 16. The presence of a mental illness or limitation of cognitive functions that prevent independent participation in the study, including the use of telemedicine services 17. Any abnormality found that is considered by the Principal Investigator a contraindication to participate in the stidy due to data interpretation or safety issue

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 75 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • American Heart of Poland
  • Provider of Information About this Clinical Study
    • Principal Investigator: Sebastian Stec, Clinical Professor, Principal Investigator – American Heart of Poland
  • Overall Official(s)
    • Sebastian M Stec, MD, PhD, Principal Investigator, American Heart of Poland
    • Krzysztof Milewski, MD, PhD, Study Director, American Heart of Poland
  • Overall Contact(s)
    • Sebastian M Stec, MD, PhD, +48 600-298-022,


Brignole M, Moya A, de Lange FJ, Deharo JC, Elliott PM, Fanciulli A, Fedorowski A, Furlan R, Kenny RA, Martin A, Probst V, Reed MJ, Rice CP, Sutton R, Ungar A, van Dijk JG; ESC Scientific Document Group. 2018 ESC Guidelines for the diagnosis and management of syncope. Eur Heart J. 2018 Jun 1;39(21):1883-1948. doi: 10.1093/eurheartj/ehy037. No abstract available.

Glikson M, Nielsen JC, Kronborg MB, Michowitz Y, Auricchio A, Barbash IM, Barrabes JA, Boriani G, Braunschweig F, Brignole M, Burri H, Coats AJS, Deharo JC, Delgado V, Diller GP, Israel CW, Keren A, Knops RE, Kotecha D, Leclercq C, Merkely B, Starck C, Thylen I, Tolosana JM; ESC Scientific Document Group. 2021 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy. Eur Heart J. 2021 Sep 14;42(35):3427-3520. doi: 10.1093/eurheartj/ehab364. No abstract available. Erratum In: Eur Heart J. 2022 May 1;43(17):1651.

Shen WK, Sheldon RS, Benditt DG, Cohen MI, Forman DE, Goldberger ZD, Grubb BP, Hamdan MH, Krahn AD, Link MS, Olshansky B, Raj SR, Sandhu RK, Sorajja D, Sun BC, Yancy CW. 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2017 Aug 1;136(5):e60-e122. doi: 10.1161/CIR.0000000000000499. Epub 2017 Mar 9. No abstract available. Erratum In: Circulation. 2017 Oct 17;136(16):e271-e272.

Klank-Szafran M, Stec S, Sledz J, Janion M. [Radiofrequency ablation and cardioneuroablation for AVNRT and atrioventricular block]. Kardiol Pol. 2010 Jun;68(6):720-4. Polish.

Aksu T, Guler TE, Bozyel S, Ozcan KS, Yalin K, Mutluer FO. Cardioneuroablation in the treatment of neurally mediated reflex syncope: a review of the current literature. Turk Kardiyol Dern Ars. 2017 Dec;45(1):33-41. doi: 10.5543/tkda.2016.55250.

Baysal E, Guler TE, Gopinathannair R, Bozyel S, Yalin K, Aksu T. Catheter Ablation of Atrioventricular Block: From Diagnosis to Selection of Proper Treatment. JACC Case Rep. 2020 Sep 15;2(11):1793-1801. doi: 10.1016/j.jaccas.2020.07.050. eCollection 2020 Sep.

Aksu T, Gopinathannair R, Bozyel S, Yalin K, Gupta D. Cardioneuroablation for Treatment of Atrioventricular Block. Circ Arrhythm Electrophysiol. 2021 Sep;14(9):e010018. doi: 10.1161/CIRCEP.121.010018. Epub 2021 Sep 1.

Wileczek A, Polewczyk A, Kluk M, Kutarski A, Stec S. Ultrasound-guided imaging for vagus nerve stimulation to facilitate cardioneuroablation for the treatment of functional advanced atrioventricular block. Indian Pacing Electrophysiol J. 2021 Nov-Dec;21(6):403-406. doi: 10.1016/j.ipej.2021.06.008. Epub 2021 Jun 26.

Josiak K, Stec S, Zysko D, Skonieczny B, Kosior J, Sledz J, Wilczek A, Stodolkiewicz-Nowarska E, Biel B, Szymkiewicz P, Skoczynski P, Karbarz D, Ludwik B, Banasiak W, Jagielski D. Safety and efficacy of His bundle pacing validated by extracardiac vagal nerve stimulation (HIS-STORY). Cardiol J. 2022;29(4):698-701. doi: 10.5603/CJ.a2022.0053. Epub 2022 Jun 15. No abstract available.

Reichert A, Wileczek A, Stec S. Cardioneuroablation for the effective treatment of recurrent vasovagal syncope to restore driving abilities. Kardiol Pol. 2022;80(11):1158-1160. doi: 10.33963/KP.a2022.0189. Epub 2022 Aug 10. No abstract available.

Gajda R, Knechtle B, Gebska-Kuczerowska A, Gajda J, Stec S, Krych M, Kwasniewska M, Drygas W. Amateur Athlete with Sinus Arrest and Severe Bradycardia Diagnosed through a Heart Rate Monitor: A Six-Year Observation-The Necessity of Shared Decision-Making in Heart Rhythm Therapy Management. Int J Environ Res Public Health. 2022 Aug 19;19(16):10367. doi: 10.3390/ijerph191610367.

Citations Reporting on Results

Pachon JC, Pachon EI, Pachon JC, Lobo TJ, Pachon MZ, Vargas RN, Jatene AD. "Cardioneuroablation"–new treatment for neurocardiogenic syncope, functional AV block and sinus dysfunction using catheter RF-ablation. Europace. 2005 Jan;7(1):1-13. doi: 10.1016/j.eupc.2004.10.003.

Pachon JC, Pachon EI, Cunha Pachon MZ, Lobo TJ, Pachon JC, Santillana TG. Catheter ablation of severe neurally meditated reflex (neurocardiogenic or vasovagal) syncope: cardioneuroablation long-term results. Europace. 2011 Sep;13(9):1231-42. doi: 10.1093/europace/eur163. Epub 2011 Jun 28.

Pachon M JC, Pachon M EI, Santillana P TG, Lobo TJ, Pachon CTC, Pachon M JC, Albornoz V RN, Zerpa A JC. Simplified Method for Vagal Effect Evaluation in Cardiac Ablation and Electrophysiological Procedures. JACC Clin Electrophysiol. 2015 Oct;1(5):451-460. doi: 10.1016/j.jacep.2015.06.008. Epub 2015 Aug 21.

Yao Y, Shi R, Wong T, Zheng L, Chen W, Yang L, Huang W, Bao J, Zhang S. Endocardial autonomic denervation of the left atrium to treat vasovagal syncope: an early experience in humans. Circ Arrhythm Electrophysiol. 2012 Apr;5(2):279-86. doi: 10.1161/CIRCEP.111.966465. Epub 2012 Jan 24.

Hu F, Zheng L, Liang E, Ding L, Wu L, Chen G, Fan X, Yao Y. Right anterior ganglionated plexus: The primary target of cardioneuroablation? Heart Rhythm. 2019 Oct;16(10):1545-1551. doi: 10.1016/j.hrthm.2019.07.018. Epub 2019 Jul 19.

Sun W, Zheng L, Qiao Y, Shi R, Hou B, Wu L, Guo J, Zhang S, Yao Y. Catheter Ablation as a Treatment for Vasovagal Syncope: Long-Term Outcome of Endocardial Autonomic Modification of the Left Atrium. J Am Heart Assoc. 2016 Jul 8;5(7):e003471. doi: 10.1161/JAHA.116.003471.

Aksu T, Golcuk E, Yalin K, Guler TE, Erden I. Simplified Cardioneuroablation in the Treatment of Reflex Syncope, Functional AV Block, and Sinus Node Dysfunction. Pacing Clin Electrophysiol. 2016 Jan;39(1):42-53. doi: 10.1111/pace.12756. Epub 2015 Oct 26.

Osorio TG, Paparella G, Stec S, Chierchia GB, de Asmundis C. Cardiac parasympathetic modulation in the setting of radiofrequency ablation for atrial fibrillation. Arch Med Sci. 2019 Apr 26;17(6):1716-1721. doi: 10.5114/aoms.2019.84717. eCollection 2021.

Piotrowski R, Baran J, Kulakowski P. Cardioneuroablation using an anatomical approach: a new and promising method for the treatment of cardioinhibitory neurocardiogenic syncope. Kardiol Pol. 2018;76(12):1736-1738. doi: 10.5603/KP.a2018.0200. Epub 2018 Oct 19. No abstract available.

Pachon-M EI, Pachon-Mateos JC, Higuti C, Santillana-P TG, Lobo T, Pachon C, Pachon-Mateos J, Zerpa J, Ortencio F, Amarante RC, Silva RF, Osorio TG. Relation of Fractionated Atrial Potentials With the Vagal Innervation Evaluated by Extracardiac Vagal Stimulation During Cardioneuroablation. Circ Arrhythm Electrophysiol. 2020 Apr;13(4):e007900. doi: 10.1161/CIRCEP.119.007900. Epub 2020 Mar 19.

Clinical trials entries are delivered from the US National Institutes of Health and are not reviewed separately by this site. Please see the identifier information above for retrieving further details from the government database.

At, we keep tabs on over 200,000 clinical trials in the US and abroad, using medical data supplied directly by the US National Institutes of Health. Please see the About and Contact page for details.