BradycardiaCRYO-CNA vs RFNCT07671898
Comparison of Focal Cryoablation vs. Radiofrequency Cardioneuroablation for Bradyarrhythmias
A study testing Focal Cryoablation and Radiofrequency Catheter Ablation in people with Bradycardia and Syncope, Vasovagal, run by Tomsk National Research Medical Center of the Russian Academy of Sciences at 1 site in Russia.
Trial summary
Bradyarrhythmias are conditions where the heart beats too slowly, causing symptoms like dizziness, fainting, and fatigue. In some patients, these slow heart rhythms are caused by overactivity of the vagus nerve (the part of the nervous system that slows the heart down). Read more about this study
- Who is it for?
- Ages 18 to 60 years
- Conditions the study is for
- Bradycardia, Syncope, Vasovagal, Sick Sinus Syndrome
- What is being tested?
- Focal Cryoablation and Radiofrequency Catheter Ablation
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteRussia
- Study dates
- 1 Sep 2024to 25 Dec 2028
- Phase
- Interventional
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 60 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Age 18 to 60 years;
- Symptomatic bradycardia (sinus bradycardia or bradycardia due to atrioventricular block, including transient);
- Severe asymptomatic sinus bradycardia (heart rate less than 30 beats per minute);
- Transient second- or third-degree atrioventricular block;
- Persistent second-degree atrioventricular block;
- Rhythm pauses greater than 6 seconds;
- Recurrent syncope or presyncope with documented association with bradycardia (without trauma);
- Positive response to atropine (heart rate increase ≥25% from baseline or >90 beats per minute) OR positive response to exercise (heart rate increase ≥25% from baseline or >90 beats per minute, OR conversion of second- or third-degree atrioventricular block to first-degree block or complete normalization of atrioventricular conduction during sinus rhythm);
Who cannot join
- Chronic antiarrhythmic drug therapy (ongoing);
- Presence of implanted pacemaker, cardiac resynchronization therapy device, or implantable cardioverter-defibrillator;
- Bradyarrhythmia secondary to medications;
- Bradyarrhythmia secondary to electrolyte imbalance (hyperkalemia);
- Bradyarrhythmia secondary to hypothyroidism;
- Bradyarrhythmia secondary to obstructive sleep apnea syndrome;
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- Absence of response to pharmacological denervation (no heart rate increase after atropine administration up to maximum dose of 0.2 mg/kg);
- Clinically significant coronary artery disease;
- Post-myocardial infarction cardiosclerosis;
- Hemodynamically significant congenital heart disease (including surgically corrected);
- Stable ventricular tachycardia in the setting of bradycardia;
- History of stroke or transient ischemic attack;
- Prior open-heart surgery;
- Prior catheter-based coronary artery intervention or percutaneous coronary intervention;
- Pregnancy or breastfeeding; Age less than 18 years Age greater than 60 years
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Russia1 site, 1 recruiting
- Recruiting
Cardiology Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences
Tomsk, Tomsk Oblast, 634012
Stanislav Yu Usenkov, PhD, +7 (3822) 55-84-01, sturus@rambler.ru
About this study
Official title: Prospective Non-Randomized Comparison of Point-by-Point Cryoablation Using Freezor™ Xtra Versus Radiofrequency Ablation Using TactiFlex™ SE of Parasympathetic Ganglia (Cardioneuroablation) in Patients With Vagally-Mediated Bradyarrhythmias
Bradyarrhythmias are conditions where the heart beats too slowly, causing symptoms like dizziness, fainting, and fatigue. In some patients, these slow heart rhythms are caused by overactivity of the vagus nerve (the part of the nervous system that slows the heart down).
Cardioneuroablation (CNA) is a catheter-based procedure that targets and reduces the effect of these overactive nerves on the heart. It is an alternative to permanent pacemaker implantation, especially for younger patients.
Read more
Traditionally, CNA is performed using radiofrequency (RF) energy to create small burns in specific areas of the heart. This study investigates whether focal cryoablation (freezing technology using the Freezor™ Xtra catheter) is as safe and effective as standard RF ablation for CNA.
This is a prospective, non-randomized study. Participants will receive either RF ablation (N=30) or cryoablation (N=30). The study will evaluate the recurrence of slow heart rhythms and fainting episodes, as well as any complications, over 12 months of follow-up.
Read the detailed description
Background and Rationale
Cardioneuroablation is an emerging treatment for vagally-mediated bradyarrhythmias, including symptomatic sinus bradycardia, atrioventricular blocks, and vasovagal syncope with a cardioinhibitory component . The procedure targets ganglionated plexi located in the epicardial fat and myocardium, which contain parasympathetic nerve endings.
While radiofrequency (RF) energy is the standard modality for CNA, epicardial fat may limit RF lesion formation when fat thickness exceeds 3 mm. Cryoablation, by contrast, uniformly cools tissue without energy dissipation in fat, potentially offering more consistent ganglion ablation.
To date, no clinical study has compared focal cryoablation versus RF ablation specifically for cardioneuroablation.
Objectives
Primary: To compare the efficacy of focal cryoablation versus RF ablation for cardioneuroablation in preventing bradyarrhythmia recurrence.
Secondary: To compare the safety profile of both techniques, including periprocedural complications and inappropriate sinus tachycardia.
Study Design
This is a prospective, non-randomized, parallel-group study conducted at a single center (Cardiology Research Institute, Tomsk NRMC). Eligible patients aged 18-60 years with symptomatic vagally-mediated bradyarrhythmias (confirmed by positive atropine test and/or EP study) are assigned non-randomly to either:
Group 1 (RF-CNA, N=30): Radiofrequency ablation using TactiFlex™ SE catheter (Abbott), power 45W, target AI 45, with irrigation
Group 2 (Cryo-CNA, N=30): Focal cryoablation using Freezor™ Xtra 6mm catheter (Medtronic), target temperature -75°C, 240 seconds per application
Procedures
All procedures are performed under intravenous sedation. After establishing venous access, a 3D electroanatomical map of the right atrium is created using the EnSite™ X system with HD Grid mapping catheter. Ganglionated plexi are identified using spectral analysis (OTNF algorithm) and anatomical landmarks (RAGP and IRGP).
Ablation is applied at identified sites. Intraprocedural endpoints include:
Reduction of SNRT <1500 ms and cSNRT <525 ms
Wenckebach point ≥140 bpm
AV node ERP >300 ms
Absence of bradycardic response to phenylephrine (<10% heart rate reduction)
Follow-up
Patients are followed at 6 and 12 months post-procedure with clinical assessment, 12-lead ECG, and 24-hour Holter monitoring.
Statistical Considerations
The planned sample size is 60 patients (30 per group). Quantitative variables will be presented as mean±SD or median [Q1;Q3]. Paired t-test or Wilcoxon test will be used for pre-post comparisons. Between-group comparisons will use Mann-Whitney U test. Statistical significance set at p<0.05.
- Being tested
- Focal Cryoablation, Radiofrequency Catheter Ablation
- Keywords
- Cardioneuroablation,, Cryoablation, Radiofrequency Ablation, Ganglionated Plexi, Parasympathetic Nervous System, Bradyarrhythmias, Functional Bradycardia, Vasovagal Syncope, Sick Sinus Syndrome, Atrioventricular Block
- Medical subject headings
- Bradycardia, Syncope, Vasovagal, Sick Sinus Syndrome, Atrioventricular Block
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Focal CryoablationProcedure or surgery
Focal cryoablation of right atrial ganglionated plexi using Freezor™ Xtra 6mm catheter (Medtronic) at -75°C for 240 seconds per application. 3-5 applications per GP zone. Positioned by fluoroscopy and impedance-based tracking in EnSite™ X system.
Radiofrequency Catheter AblationProcedure or surgery
Radiofrequency ablation of right atrial ganglionated plexi using TactiFlex™ SE catheter (Abbott) with power up to 45W, temperature 50°C, target AI 45, with irrigation. 3-5 applications per GP zone. Guided by EnSite™ X mapping system and spectral analysis (OTNF).
| Study group | Role | What they receive |
|---|---|---|
| CryoCNA | Experimental | Not described Receives: Procedure: Focal Cryoablation |
| RF CNA | Active comparator | Not described Receives: Procedure: Radiofrequency Catheter Ablation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Recurrence of Bradyarrhythmia or Syncope
Documented recurrence of symptomatic bradyarrhythmia (sinus bradycardia <40 bpm, pause >3 sec, AV block) or syncope confirmed by ECG or Holter
Measured: 12 months
Secondary outcomes (7)
Pericardial Effusion or Hemopericardium
Pericardial effusion or hemopericardium requiring intervention, confirmed by echocardiography
Measured: Periprocedural (7 days)
Inappropriate Sinus Tachycardia
Sustained sinus tachycardia >100 bpm without cause, requiring beta-blocker therapy
Measured: 12 months
Vascular Access Complications
Hematoma, pseudoaneurysm, or AV fistula requiring treatment, confirmed by ultrasound
Measured: Periprocedural (7 days)
Change in Minimum Heart Rate
Absolute change in minimum heart rate (bpm) on 24-hour Holter from baseline to 6 months
Measured: Baseline to 6 months
Change in Maximum Heart Rate
Absolute change in maximum heart rate (bpm) on 24-hour Holter from baseline to 6 months
Measured: Baseline to 6 months
Change in Electrophysiological Parameters
Normalization of cSNRT <525 ms, Wenckebach point ≥140 bpm, AV-ERP >300 ms
Measured: Intraprocedural
Change in Mean Heart Rate
Absolute change in minimum heart rate (bpm) on 24-hour Holter from baseline to 6 months
Measured: Baseline to 6 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Jun 2026
- Study start1 Sep 2024
- Primary completion25 Dec 2027 (estimated)
- Study completion25 Dec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for BradycardiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Tomsk National Research Medical Center of the Russian Academy of Sciences
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07671898
- Sponsor's protocol ID
- CRI-281/2
- Acronym
- CRYO-CNA vs RF
- Status last verified
- Jun 2026
- First submitted
- 22 Jun 2026
- Last updated
- 26 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No