A randomised comparison of cardioversion and catheter cryoablation in patients with persistent atrial fibrillation

Plain English Summary

Background and study aims
Persistent atrial fibrillation (AF) is the most common sustained heart rhythm disorder and is associated with a variety of symptoms including lethargy and breathlessness. This can be treated with cardioversion with long-term medication, or a more definitive treatment with ablation. The usual first line treatment for persistent AF is cardioversion but recurrence rates following this are up to 90%. The aim of this study is to determine whether cryoablation is more effective than cardioversion at preventing recurrence of persistent AF.

Who can participate?
Patients aged over 18 with persistent AF who are suitable for cryo catheter ablation

What does the study involve?
Participants are randomly allocated to one of two groups. Group 1 undergo AF ablation with pulmonary vein isolation using cryoablation. Cryoablation is a minimally invasive procedure and has a success rate of between 57-69% in treating persistent AF. The procedure involves passing two tubes into a vein from the groin. After crossing to the left chamber of the heart (atrium), a balloon is used to engage the pulmonary veins which are then frozen. The procedure lasts around 90 minutes. Group 2 undergo cardioversion, which involves a controlled electric shock to the chest wall under general anaesthesia or heavy sedation. This is usually performed as a day case procedure. Participants are followed up with three clinic visits 3, 6 and 12 months later, along with a 24-hour Holter monitor to assess symptoms and medication review as well as a telephone interview at 9 months. All patients are provided with and trained to use a home monitor to send weekly ECGs and further ECGs at times of symptoms. Patients are also asked to complete questionnaire forms at the beginning and end of the study.

What are the possible benefits and risks of participating?
Depending on the group participants are allocated to, taking part in this study may involve exposure to ionising radiation through x-ray imaging. This will occur if participants are in the cryoablation group (not cardioversion). The cryoablation procedure may or may not be considered part of normal standard of care. Participant’s local study centre will be able to advise on whether this is the case.
The dose of radiation from this procedure could be up to 7.4 mSv. This represents a total lifetime cancer risk of about 1 in 1400 for females aged between 20 and 29 years (the risk reduces for older patients and is lower for male patients). This compares to a natural baseline lifetime risk of getting cancer in the UK of about 1 in 3. This dose of radiation is equivalent to about 3.4 years of natural background radiation to which we are all subjected. As this is an invasive procedure, there are risks associated with it. These risks are small but include bleeding and vascular problems (1%), phrenic nerve damage (1%), stroke (0.25%), pericardial effusion (2%) and death (0.1%). There are no additional risks in taking part in the study. During the study and ablation procedure, there will be a full complement of catheter laboratory staff present who are fully trained to deal with urgent medical situations. The risks of cardioversion include superficial burns and chest discomfort. It is important that participants remember to take their anticoagulation medication to minimize the risk of stroke.

Where is the study run from?
1. Brighton and Sussex University Hospitals NHS Trust (UK)
2. Portsmouth Hospitals NHS Trust (UK)
3. University Hospital Southampton NHS Foundation Trust (UK)
4. East Sussex Healthcare NHS Trust (UK)
5. Leeds Teaching Hospitals NHS Trust (UK)

When is the study starting and how long is it expected to run for?
August 2017 to September 2021

Who is funding the study?
Medtronic (USA)

Who is the main contact?
Duncan Fatz, duncan.fatz@nhs.net

Contact information

Study information

Eligibility

Locations

Countries of recruitment

• England
• United Kingdom

Study participating centres

Sponsor information

Funders

Funder type

Industry

Results and Publications

Study outputs

Additional files

ISRCTN38385178 _BasicResults.pdf

Editorial Notes

23/06/2023: The basic results have been uploaded to the study outputs table.
08/12/2021: The following changes have been made:
1. The overall trial end date has been changed from 30/11/2020 to 24/09/2021 and the plain English summary has been updated to reflect this change.
2. The total final enrolment number has been added.
3. The intention to publish date has been changed from 31/01/2021 to 30/07/2022.
09/09/2020: The overall trial end date was changed from 01/02/2020 to 30/11/2020.
16/07/2019: The following changes have been made:
1. The trial contact has been updated and the plain English summary has been updated accordingly.
2. The recruitment end date has been changed from 01/02/2019 to 30/09/2019.
3. The condition has been changed from "Specialty: Cardiovascular disease, Primary sub-specialty: Arrhythmia; UKCRC code/ Disease: Cardiovascular/ Other forms of heart disease" to "Atrial fibrillation" and the condition category from 'Respiratory' to 'Circulatory system' following a request from the NIHR.
14/03/2019: The trial contact has been updated.
12/03/2019: The trial contact has been updated.