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Cryoballoon Ablation as First Line Treatment of Atrial Flutter (CRAFT)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT03401099
Recruitment Status : Active, not recruiting
First Posted : January 17, 2018
Last Update Posted : December 20, 2021
Medtronic International Trading Sarl
Information provided by (Responsible Party):
Liverpool Heart and Chest Hospital NHS Foundation Trust

Brief Summary:

Current guidelines recommend radiofrequency catheter ablation of the cavotricuspid isthmus as treatment for symptomatic/drug-refractory atrial flutter, in spite of the fact that recurrences of flutter and incidence of post-ablation atrial fibrillation are common.

In this study, the investigators assess the hypothesis that the use of cryoballoon Pulmonary Vein Isolation ('novel' treatment) to achieve the electrical disconnection between the pulmonary veins and the heart will lead to higher rates of freedom from abnormal heart rhythms (atrial flutter, atrial fibrillation, or atrial tachycardia) and more improved quality of life than treatment using heat energy (radiofrequency ablation) directed at the cavotricuspid isthmus ('conventional treatment').

Condition or disease Intervention/treatment Phase
Atrial Flutter Typical Procedure: Radiofrequency ablation of CTI Procedure: Cryoballoon PVI Not Applicable

Detailed Description:

Atrial flutter and atrial fibrillation are believed to share the same initiating triggers in the form of pulmonary vein ectopy. Cavo-tricuspid isthmus-dependent atrial flutter almost always results from short bursts of antecedent atrial fibrillation. Radiofrequency (RF) ablation of the cavo-tricuspid isthmus (CTI) is the current accepted first-line treatment for atrial flutter, although post-ablation atrial fibrillation commonly occurs, even in the absence of pre-existing atrial fibrillation.

Cryoballoon Pulmonary Vein Isolation (PVI) has become an established treatment for atrial fibrillation. In patients with both atrial flutter and fibrillation, PVI alone has been shown to control both types of atrial arrhythmia, with no benefit derived from supplemental RF CTI ablation.

This study aims to demonstrate that standalone cryoballoon PVI for typical atrial flutter without RF CTI ablation will lead to a significant difference in preventing recurrence of atrial arrhythmia compared to radiofrequency ablation of the CTI, and should be offered as first-line therapy.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 130 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Intervention Model Description: Participants will be randomised 1:1 into two groups to receive either of the two treatments.
Masking: Single (Outcomes Assessor)
Masking Description: Blinded outcome assessment
Primary Purpose: Treatment
Official Title: Cryoballoon Pulmonary Vein Isolation as First Line Treatment for Typical Atrial Flutter
Actual Study Start Date : August 17, 2018
Actual Primary Completion Date : December 1, 2021
Estimated Study Completion Date : December 30, 2023

Arm Intervention/treatment
Active Comparator: Radiofrequency ablation of CTI
Radiofrequency ablation of CTI (cavo-tricuspid isthmus), which is the 'conventional' treatment of atrial flutter
Procedure: Radiofrequency ablation of CTI
Delivery of radiofrequency energy to the cavotricuspid isthmus (region of right atrial tissue between the tricuspid annulus and the inferior vena cava) until bidirectional block is achieved
Other Name: CTI ablation

Active Comparator: Cryoballoon PVI
Cryoballoon PVI (Pulmonary Vein Isolation), which is the 'novel treatment'
Procedure: Cryoballoon PVI
Cryoballoon application to the pulmonary veins aiming for Pulmonary Vein Isolation
Other Name: Cryoablation Pulmonary Vein Isolation

Primary Outcome Measures :
  1. Time to first recurrence of sustained, symptomatic supraventricular arrhythmia (Atrial Fibrillation, Atrial Flutter or Atrial Tachycardia) following a blanking period of 4 weeks after a single ablation procedure [ Time Frame: After 4 weeks of ablation treatment (blanking period) up to 12 months of follow up ]
    'Sustained' is defined as lasting >30 seconds. 'Symptomatic' is defined as acute onset awareness of palpitations, breathlessness, dizziness, fatigue or chest pain associated with patient activation of the loop recorder.

Secondary Outcome Measures :
  1. Time to first symptomatic or asymptomatic Atrial Fibrillation lasting ≥2 min [ Time Frame: After 4 weeks of ablation treatment (blanking period) up to 12 months of follow up ]
    How long it takes until first occurrence of atrial fibrillation (associated with symptoms or no symptoms) lasting 2 or more minutes after blanking period. Two minutes is the minimum duration detectable by the loop recorder

  2. Total Burden of Atrial fibrillation over 12 months [ Time Frame: After 4 weeks of ablation treatment (blanking period) up to 12 months of follow up ]
    The total occurrence of atrial fibrillation recorded by the loop recorder (symptomatic or asymptomatic) during the follow-up period

  3. Time to first symptomatic or asymptomatic atrial flutter/atrial tachycardia [ Time Frame: After 4 weeks of ablation treatment (blanking period) up to 12 months of follow up ]
    Occurrence of atrial flutter/atrial tachycardia with/without symptoms following the blanking period

  4. Incidence of any significant arrhythmia [ Time Frame: After first ablation procedure, through study completion, an average of 12 months ]
    Incidence of any arrhythmia requiring medical visit to primary or secondary care, or hospitalisation, or leading to death

  5. Total burden of abnormal heart rhythm measured by the implantable loop recorder [ Time Frame: After first ablation procedure through study completion or time of intervention, whichever comes first, assessed up to 12 months ]
    Total arrhythmic burden up to end of follow up or up to time of intervention (either cardioversion or ablation), whichever comes first.

  6. Incidence of repeat electrophysiological interventional procedure (repeat catheter ablation, or DCCV) over the follow-up period. [ Time Frame: After 4 weeks of ablation treatment (blanking period) up to 12 months of follow up ]
    Occurrence of repeat ablations/cardioversion

  7. Incidence of procedural complications [ Time Frame: During and after ablation procedure, through study completion, an average of 12 months ]
    Composite of cardiac tamponade requiring drainage, persistent phrenic nerve palsy lasting >24 hours, serious vascular complications requiring intervention or delaying discharge, stroke/transient ischaemic attack, requirement for a permanent pacemaker, atrio-esophageal fistula, or death

  8. Incidence of all-cause hospitalisations [ Time Frame: After first ablation procedure, through study completion, an average of 12 months ]
    Any hospital admission post-ablation

  9. Quality of Life questionnaire [ Time Frame: At baseline and at 12 months ]
    Quality of life as assessed by the standard EuroQol Group's 5-dimensional questionnaire. This comprises 5 dimensions (mobility, self-care, usual activities, pain/discomfort and anxiety/depression) and the visual analogue scale. The single digits for the five dimensions will be combined into a 5-digit number that describes the patient's health state.

  10. Procedural duration [ Time Frame: Only during the first ablation procedure ]
    Duration of ablation measured in minutes for either treatment

  11. Total Fluoroscopy times [ Time Frame: Only during the first ablation procedure ]
    The total time in minutes during which patient will be exposed to radiation under each of the two treatment techniques

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 80 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • 1. Age 18-80 years
  • 2. Patients referred for catheter ablation for typical atrial flutter. The atrial flutter may be either persistent or paroxysmal, with at least one episode having been documented on 12-lead ECG. In the view of the treating physician, the ECG morphology should be compatible with a CTI-dependent circuit, either counterclockwise or clockwise.

Exclusion Criteria:

  • 1. Any evidence of previously documented atrial fibrillation
  • 2. Previous cavo-tricuspid isthmus ablation or atrial fibrillation ablation
  • 3. Atrial flutter documented solely on Ambulatory monitoring
  • 4. Atrial flutter morphology on ECG suggestive of a left atrial flutter
  • 5. History of atrial flutter with 1:1 atrioventricular conduction and haemodynamic compromise
  • 6. Indwelling atrial-septal defect occluder device, or any anatomical reason that precludes left atrial access
  • 7. Left atrial diameter (PLAX M-mode) >5.5 cm
  • 8. Severe left ventricular dysfunction (LV ejection fraction < 30% on Echocardiography)
  • 9. Recent stroke/transient ischaemic attack within 3 months
  • 10. Inability or unwillingness to take oral anticoagulant treatment
  • 11. Morbid obesity (Body Mass Index ≥40)
  • 12. Extreme frailty (A score of 7,8 or worse on the Clinical Frailty Scale)
  • 13. Implanted metal prosthetic valve(s) in mitral position
  • 14. Indwelling cardiac resynchronisation therapy device, pacemaker or implantable cardioverter defibrillator
  • 15. Advanced Renal dysfunction (eGFR<30 ml/min)
  • 16. Pregnancy
  • 17. Severe valvular heart disease of any kind as assessed by the investigator
  • 18. Previous valve replacement surgery or other prosthetic heart valve

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03401099

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University Hospital Basel
Basel, Switzerland
University Hospital Inselspital Bern
Bern, Switzerland
United Kingdom
Royal Papworth Hospital NHS Foundation Trust
Papworth Everard, Cambridge, United Kingdom, CB23 3RE
Leeds Teaching Hospitals NHS Trust
Leeds, United Kingdom
Liverpool Heart and Chest Hospital NHS Foundation Trust
Liverpool, United Kingdom, L14 3PE
Manchester University NHS Foundation Trust, Wythenshawe Hospital
Manchester, United Kingdom, M23 9LT
South Tees Hospitals NHS Foundation Trust, James Cook University Hospital
Middlesbrough, United Kingdom, TS4 3BW
The Newcastle Upon Tyne Hospital NHS Foundation Trust, Freeman Hospital
Newcastle Upon Tyne, United Kingdom, NE7 7DN
Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital
Oxford, United Kingdom, OX3 9DU
University Hospitals Plymouth NHS Trust
Plymouth, United Kingdom
Sponsors and Collaborators
Liverpool Heart and Chest Hospital NHS Foundation Trust
Medtronic International Trading Sarl
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Study Chair: Dhiraj Gupta, MBBS MD FRCP Liverpool Heart and Chest Hospital
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
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Responsible Party: Liverpool Heart and Chest Hospital NHS Foundation Trust
ClinicalTrials.gov Identifier: NCT03401099    
Other Study ID Numbers: 1153
First Posted: January 17, 2018    Key Record Dates
Last Update Posted: December 20, 2021
Last Verified: December 2021
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Plan Description:

There is no plan to share Individual Participant Data with other researchers.

Supporting information that will be shared are only:

Study Protocol, Statistical Analysis Plan (SAP), and Clinical Study Report (CSR)

Data will be available after about 6 months for about 5 years.

Criteria for which Individual Participant Data and any additional supporting information will be shared, including with whom, for what types of analyses, and by what mechanism:

These will be shared with research co-workers, for results, statistical analysis and conclusions. Communication of anonymized data will be done via secure mails and emails.

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by Liverpool Heart and Chest Hospital NHS Foundation Trust:
Radiofrequency ablation
Cavo-tricuspid isthmus
Pulmonary Vein Isolation
Cryoballoon ablation
Additional relevant MeSH terms:
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Atrial Flutter
Arrhythmias, Cardiac
Heart Diseases
Cardiovascular Diseases
Pathologic Processes