RecruitingInterventional

Atrial fibrillation ablation versus heart rate control using conduction system pacing with ablation of the atrioventricular node

Having both atrial fibrillation (an irregular heartbeat) and heart failure can cause tiredness, breathlessness, and frequent hospital visits. Doctors usually manage these conditions using one of two routine procedures when medications are not enough. The first is catheter ablation, which uses gentle heat or freezing to calm the chaotic electrical signals in the heart. The second involves fitting a modern pacemaker that works with the heart's natural wiring, paired with a small procedure to stop faulty signals reaching the main pumping chambers. While both options are already widely used in hospitals, they have never been compared directly. The ABACUS trial aims to find out which approach offers better long-term health and keeps patients out of hospital. Men and women aged 60 and over who join the study will receive one of the two treatments and will be followed closely for at least one year.

At a glance

Status

Recruiting

Sponsor

University Hospital of Geneva

Enrolment target

220

Start

24 Oct 2024

Estimated completion

20 Aug 2027

Persistent atrial fibrillation and heart failure

What is this study about?

The heart relies on smooth, regular electrical signals to pump blood around the body. In atrial fibrillation, these signals become chaotic, making the upper chambers beat rapidly and unevenly. When someone also has heart failure—where the heart muscle does not pump as strongly as it should—this irregular rhythm puts extra strain on the heart, leading to breathlessness, fatigue, and sudden trips to hospital.

Doctors have two main hospital procedures to treat this problem when tablets are no longer working well. One method is catheter ablation. A specialist gently guides thin tubes into the heart to create tiny scars that block faulty electrical pathways, aiming to bring back a normal rhythm. The other method is fitting a pacemaker directly into the heart's natural electrical wiring, alongside a procedure to block the chaotic rhythm from reaching the lower chambers. This allows the pacemaker to take full, steady control of the heartbeat.

Both of these treatments are safe, routine options used in everyday healthcare. However, specialists do not yet know whether one is better than the other at preventing serious complications. The ABACUS study has been designed to directly compare the two strategies side by side to see which one provides better outcomes for heart health.

By taking part, participants help doctors understand which treatment works best. The findings will help shape future NHS and international guidelines, making it easier for specialists to choose the most effective treatment for people living with heart failure and persistent atrial fibrillation.

Key takeaways

Compares two standard hospital procedures for persistent atrial fibrillation and heart failure.
Open to adults aged 60 and over who still have symptoms despite medication.
Both treatments are well-tested, routine procedures rather than experimental therapies.
Participants are followed up closely for at least one year to monitor heart health and daily well-being.
Taking part is entirely voluntary, and you can leave the study at any point.

Who may be eligible?

This study is designed for adults aged 60 and older who have persistent atrial fibrillation (meaning the irregular heartbeat has lasted continuously for more than a week) alongside heart failure that still causes symptoms despite taking prescribed medications.

To be considered, you must have visited a hospital, emergency department, or heart clinic for heart failure at least once in the past two years, with routine blood tests showing signs of heart strain. Your doctor must also confirm that you are medically suitable to receive either of the two procedures being compared.

You will not be able to take part if you have very advanced heart failure with very low blood pressure, or if you have had a heart attack or stroke within the past three months. People who already have a pacemaker or who are scheduled for major surgery will also be unable to join.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am aged 60 or older.
I have been diagnosed with persistent atrial fibrillation lasting more than 7 days.
I have heart failure and still experience symptoms like breathlessness or fatigue.
I have attended hospital or a clinic for heart failure in the last two years.
I have not had a heart attack or stroke in the last three months.
I do not already have a permanent pacemaker fitted.

Answer every question to see your result.

What does participation involve?

If you decide to take part, a computer will randomly place you into one of two treatment groups, similar to flipping a coin. One group will receive catheter ablation, while the other group will receive the special pacemaker and the procedure to control heart rate. Both treatments are standard hospital procedures performed by experienced heart specialists. After your procedure, you will stay on your recommended heart medications and attend regular follow-up clinic visits. During these visits, doctors will check your heart rhythm, perform standard health tests, and ask you to complete short questionnaires about your energy levels and quality of life. You will be monitored closely for at least 12 months, with the whole study scheduled to run until late 2028.

Potential risks and benefits

A key benefit of taking part is that your heart health will be monitored very thoroughly by a team of heart specialists, and your results will help improve care for future patients. Because both procedures are already widely used in routine practice, the risks are the same as having these standard hospital treatments outside of a trial. These can include bruising or bleeding where the catheters are inserted, minor device complications, or occasional rhythm changes. Joining the study is completely your choice. You can change your mind and withdraw at any time without giving a reason, and your regular medical care will never be affected.

Locations (29)

National Heart and Lung Institute, Imperial College London
City only
London, England
University Hospital of Geneva
City only
Geneva, Switzerland
Inselspital Bern
Approximate
Bern, Switzerland
Univestiy Hospital of Zurich
City only
Zurich, Switzerland
University Hospital of Basel
City only
Basel, Switzerland
IRCCS Policlinico
Unverified
Bologna, Italy
Ospedale Santa Maria della Misericordia
Unverified
Rovigo, Italy
Ospedale Maggiore Della Carità Di Novara
Unverified
Novara, Italy
University Hospital of Ferrara
Unverified
Cona, Italy
Herzzentrum Leipzig
Unverified
Leipzig, Germany
Medizinische Fakultät OWL
Unverified
Bad Oeynhausen, Germany
Herzzentrum Bremen
Unverified
Bremen, Germany

Common questions

What is the main goal of this trial?

The trial aims to find out whether a special pacemaker system is just as effective as catheter ablation at keeping people with heart failure and atrial fibrillation out of hospital.

Can I pick which procedure I receive?

No. A computer will randomly assign you to one of the two groups. This ensures the results are completely unbiased and scientifically fair.

Are the treatments experimental?

No. Both catheter ablation and pacemaker implantation are established, approved procedures already performed routinely in hospitals.

How long will I be in the study?

After your procedure, you will attend regular check-ups and be followed closely by the research team for at least one year.

What happens if I decide to stop taking part?

You are free to leave the trial at any time. Your doctors will simply continue your treatment using standard NHS care.

How to find out more

Haran Burri

haran.burri@hug.ch +41 (0)22 372 72 00 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.