Comparison of PolarX and the Arctic Front Cryoballoons for PVI in Patients With Symptomatic Paroxysmal AF (COMPARE-CRYO)

July 23, 2026 updated by: Insel Gruppe AG, University Hospital Bern

Comparison of the PolarX and the Arctic Front Cryoballoon for Pulmonary Vein Isolation in Patients With Symptomatic Paroxysmal Atrial Fibrillation - A Multi-Center Non-Inferiority Design Clinical Trial

Pulmonary vein isolation (PVI) is an effective treatment for atrial fibrillation (AF). Single shot devices are increasingly used for PVI. Currently, Medtronic Arctic Front cryoballoon is the most frequently used single shot technology and hence is the benchmark for upcoming technologies. A novel cryoballoon technology has recently been introduced (PolarX, Boston Scientific). However, whether PolarX provides effectiveness similar to the standard-of-practice Medtronic Arctic Front cryoballoon is yet to be investigated. Given that PolarX was developed considering the reported limitations and potential failures associated with the Medtronic Arctic Front cryoballoon, it might be even more effective and safe for use in AF ablation procedures.

The aim of this trial is to compare the efficacy and safety of the PolarX Cryoballoon (Boston Scientific) and the Arctic Front Cryoballoon (Medtronic) in patients with symptomatic paroxysmal AF undergoing their first PVI.

This is an investigator-initiated, multicenter, randomized controlled, open-label trial with blinded endpoint adjudication. Given that the Medtronic Arctic Front Cryoballoon is the standard-of-practice for single shot PVI and the PolarX is the novel technology, this trial has a non-inferiority design.

The hypothesis with regards to the primary efficacy endpoint is that the PolarX Cryoballoon (Boston Scientific) shows lower efficacy compared to the Arctic Front Cryoballoon (Medtronic) and that therefore more episodes of first recurrence of any atrial arrhythmia between days 91 and 365 will be observed in patients with symptomatic paroxysmal AF undergoing their first PVI. Hence the alternative hypothesis postulates that the PolarX Cryoballoon is non-inferior to the Arctic Front Cryoballoon. Rejection of the null hypothesis is needed to conclude non-inferiority.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
202

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Switzerland
      • Basel, Switzerland, 4031
        • University Hospital Basel
      • Bern, Switzerland, 3010
        • Inselspital, Bern University Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

14 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Paroxysmal atrial fibrillation documented on a 12 lead electrocardiogram (ECG) or Holter monitor (lasting ≥30 seconds) within the last 24 months. According to current guidelines, paroxysmal is defined as any atrial fibrillation (AF) that converts to sinus rhythm within 7 days either spontaneously or by pharmacological or electrical cardioversion.
  • Candidate for ablation based on current AF guidelines
  • Continuous anticoagulation with warfarin (International Normalized Ratio [INR] 2-3) or a novel oral anticoagulant (NOAC) for ≥4 weeks prior to the ablation; or a transesophageal echocardiogram (TEE) that excludes left atrial (LA) thrombus ≤48 hours before ablation
  • Age of 18 years or older on the date of consent
  • Informed Consent as documented by signature (Appendix Informed Consent Form)

Exclusion Criteria:

  • Previous LA ablation or LA surgery
  • AF due to reversible causes (e.g. hyperthyroidism, cardiothoracic surgery)
  • Intracardiac thrombus
  • Pre-existing pulmonary vein stenosis or pulmonary vein stent
  • Pre-existing hemidiaphragmatic paralysis
  • Contraindication to anticoagulation or radiocontrast materials
  • Cardiac valve prosthesis
  • Clinically significant (moderately-severe or severe) mitral regurgitation or stenosis
  • Myocardial infarction, percutaneous coronary intervention (PCI)/ percutaneous transluminal coronary angioplasty (PTCA), or coronary artery stenting during the 3-month period preceding the consent date
  • Cardiac surgery during the three-month interval preceding the consent date or scheduled cardiac surgery/transcatheter aortic valve implantation (TAVI) procedure
  • Significant congenital heart defect (including atrial septal defects or pulmonary vein abnormalities but not including patent foramen ovale)
  • New York Heart Association (NYHA) class III or IV congestive heart failure
  • Left ventricular ejection fraction (LVEF) <35%
  • Hypertrophic cardiomyopathy (wall thickness >1.5 cm)
  • Significant chronic kidney disease (CKD; estimated glomerular filtration rate [eGFR] <30 μMol/L)
  • Uncontrolled hyperthyroidism
  • Cerebral ischemic event (stroke or TIA) during the six-month interval preceding the consent date
  • Ongoing systemic infections
  • History of cryoglobulinemia
  • Pregnancy*
  • Life expectancy less than one (1) year per physician opinion
  • Currently participating in any other clinical trial of a drug, device or biological material during the duration of this study.

  • Unwilling or unable to comply fully with study procedures and follow-up.

    • To exclude pregnancy a blood test (human chorionic gonadotropin [HCG]) is used.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: PVI using the Arctic Front Cryoballoon (Medtronic)
Pulmonary vein isolation using the Arctic Front Cryoballoon (Medtronic)
Device: PVI using the Arctic Front Cryoballoon (Medtronic)

Patients randomized to the Arctic Front cryoballoon group will undergo PVI using the Arctic Front Cryoballoon (Medtronic).

At the end of the procedure, an implantable cardiac monitor (Medtronic Reveal LINQ) will be implanted for the purpose of continuous arrhythmia monitoring.

Other Names:
  • Arctic Front Cryoballoon
Active Comparator: PVI using the PolarX Cryoballoon (Boston Scientific)
Pulmonary vein isolation using the PolarX Cryoballoon (Boston Scientific)
Drug: PVI using the PolarX Cryoballoon (Boston Scientific)

Patients randomized to PolarX cryoballoon group will undergo PVI using the PolarX Cryoballoon (Boston Scientific).

At the end of the procedure, an implantable cardiac monitor (Medtronic Reveal LINQ) will be implanted for the purpose of continuous arrhythmia monitoring.

Other Names:
  • PolarX Cryoballoon

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Number of Patients With Recurrence of Any Atrial Tachyarrhythmia
Time Frame: days 91 to 365 post-ablation
Number of patients with recurrence of any atrial tachyarrhythmia (atrial fibrillation [AF], atrial flutter [AFL] or atrial tachycardia [AT]) between days 91 and 365 post ablation as detected on continuous implantable cardiac monitor (ICM). AF, AFL or AT will qualify as a recurrence after ablation if it lasts 120 s or longer on ICM (the minimum programmable episode interval).
days 91 to 365 post-ablation

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Number of Participants With Complications
Time Frame: days 0 to 30 post-ablation

Composite endpoint composed of:

  • cardiac tamponade requiring drainage
  • persistent phrenic nerve palsy lasting >24 hours
  • serious vascular complications requiring intervention
  • stroke/TIA
  • atrioesophageal fistula
  • death
days 0 to 30 post-ablation
Total Procedure Time
Time Frame: Day 1
Total procedure time from femoral vein puncture to sheath removal
Day 1
Total Left Atrial (LA) Indwelling Time
Time Frame: Day 1
Total LA indwelling time, from transseptal puncture to removal of LA catheters
Day 1
Total Cryoablation Time
Time Frame: Day 1
procedural endpoint
Day 1
Total Number of Cryoapplications Per Patient/Per Vein
Time Frame: Day 1
procedural endpoint
Day 1
Time to Effect
Time Frame: Day 1
disappearance of PV-Signal; procedural endpoint
Day 1
Nadir Temperatures
Time Frame: Day 1
procedural endpoint
Day 1
Total Fluoroscopy Time
Time Frame: Day 1
procedural endpoint
Day 1
Radiation Dose
Time Frame: Day 1
procedural endpoint
Day 1
Contrast Agent Usage
Time Frame: Day 1
unit measure ml; procedural endpoint
Day 1
Number of Patients With Veins With PV Signals Visible Before Cryoablation
Time Frame: Day 1
procedural endpoint
Day 1
Number of Participants With Phrenic Nerve Palsy
Time Frame: Day 1
procedural endpoint
Day 1
Number of Patients With Recurrence of Atrial Tachyarrhythmia
Time Frame: between days 1 and 90 after ablation
Follow up Endpoint
between days 1 and 90 after ablation
Overall AF Burden = % Time in AF
Time Frame: 91-365 days
Assessed by the ICM Core Lab post implantation
91-365 days
Number of Hospital Admissions or Emergency Room Visits Because of Documented Recurrence of Atrial Arrhythmias
Time Frame: Day 0 (after ablation) until day 365 post-ablation
based on telephone follow-up
Day 0 (after ablation) until day 365 post-ablation
Number of Electrical Cardioversion Because of Documented Recurrence of Atrial Arrhythmias
Time Frame: Day 0 (post-ablation) to day 365 after ablation
based on telephone follow-up
Day 0 (post-ablation) to day 365 after ablation
Number of Repeat Ablation Procedure Because of Documented Recurrence of Atrial Arrhythmias
Time Frame: Day 1 - 365 postablation
based on telephone follow-up
Day 1 - 365 postablation
Evolution of Quality of Life (QoL)
Time Frame: Change in score from BL to 12 months
Evolution of Quality of Life (QoL) from BL to 12 months. Patients rated their health on a scale from 0 to 100, with 100 being the best possible score and 0 the worst possible score. A positive number in the outcome measure means that BL's health has improved at 12 months. A negative number in the outcome measure means that BL's health has declined at 12 months.
Change in score from BL to 12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Insel Gruppe AG, University Hospital Bern

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
University Hospital, Basel, Switzerland

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Tobias Reichlin, MD, Inselspital, Bern University Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 29, 2021

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 31, 2023

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 24, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 10, 2020

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 11, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 12, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 24, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 23, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2020-02076

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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