SEE MORE AF
Research type
Research Study
Full title
Simultaneous Endo-Epicardial Mapping of Recurrent Atrial Fibrillation
IRAS ID
257470
Contact name
Scott Harfield
Contact email
Sponsor organisation
Brighton and Sussex University Hospitals NHS Trust
ISRCTN Number
ISRCTN30513341
Duration of Study in the UK
3 years, 0 months, 1 days
Research summary
Research Summary
Atrial fibrillation (AF) is the most common clinical cardiac rhythm disturbance affecting 1 in 200 people regardless of age. The underlying mechanism has been much debated, and this in part is likely to affect success rates in the treatment of AF. At present, standard care involves a procedure called an ablation. Small burn marks are made inside the heart in an attempt to correct the irregular heart beat. Unfortunately the success rate for treatment is around 50% for patients with persistent AF.
At present, maps of electrical activation and ablation treatment are only undertaken within the heart chamber. Some areas of heart muscle are very thick, and it can be difficult to achieve ablation through the full thickness of the muscle, which is the desired effect. In addition to this standard care, we aim to produce maps and deliver ablation treatment to the outside of the heart surface. The technique to treat both sides of the heart has been done for different heart rhythm problems with good effect.
Lay summary of study results
Simultaneous Endo-Epicardial Mapping of Recurrent Atrial Fibrillation (SEE MORE AF) This lay results summary has been reviewed by the UHSussex Research Champions, including members of the public, patients and patient representatives.
Background and study set up
The sponsor of this study was Brighton and Sussex University Hospitals NHS Trust (now known as University Hospitals Sussex NHS Foundation Trust), and they would like to thank everyone who took part and made this study possible.
The study (SEE MORE AF) took place between 24 November 2020 and 16 December 2022, with single centre patient recruitment of 20 patients at the Royal Sussex County Hospital. All interventions were clinically indicated, and therefore no external funding was required. A clinical fellow was assigned to manage SEE MORE AF, with funding from Abbott Medical UK as an annually recurring arrangement.
Atrial fibrillation (AF) is the most common heart rhythm disturbance, with results in the heart going in to an irregular heart rhythm. AF affects around 1.4 million people in the UK, with this number being widely predicted to double by 2050. Common symptoms that a patient might experience include palpitations, breathlessness, and fatigue. One of the most feared complications of AF is either a stroke or (TIA), which is similar to a stroke, but the symptoms last a short time. You get stroke symptoms because a clot is blocking the blood supply to the brain. When the clot moves away, the stroke symptoms stop.
AF is categorised into 4 types, and relates to the duration of AF episode:
1. Paroxysmal AF – episodes come and go, and usually stop within 48 hours without any treatment.
2. Persistent AF – each episode lasts for longer than 7 days (or less when it's treated).
3. Long-standing persistent AF – where an episode of AF has persisted for over 1 year.
4. Permanent AF – present all the time with no plans to restore normal rhythm.
Rhythm control management of AF can be achieved by 3 different ways:
1. Chemical cardioversion – Specific drugs can sometimes be used to restore the normal heart rhythm. Many of these drugs come with significant side effects and are generally not suitable for long term or indefinite use.
2. Electrical cardioversion – a procedure in which a short general anaesthetic is administered, or sedation medications are used to facilitate the delivery of a specially timed electric shock to restore the normal heart rhythm. Although the immediate success from this procedure is highly successful, at least 50% of patients are back in AF within 1 year, and 80% of patients are back in AF within 5 years.
3. Catheter ablation – a procedure performed under general or local anaesthetic, in which tubes are inserted into the vein at the top of the leg to allow specialised catheters to be introduced into the heart. Catheters can be used to deliver energy directly to the heart tissue in order to destroy (ablate) specific areas of heart muscle which are responsible for causing AF. There are three main types of energy that can be used to ablate heart muscle, and include freezing (cryoablation), heating/burning (radiofrequency), or a non-thermal energy (pulsed field ablation).
Single procedure success in treating patients with persistent AF is low at around 50%, even when using catheter ablation. One of the major challenges when undertaking ablation is the ability to create ablation marks (scars) in the heart that are continuous throughout the full thickness of the heart muscle – from the inside surface of the heart to the outside surface of the heart. In the event that ablation marks are not full thickness, there are data to demonstrate that this can cause additional heart rhythm problems in the future. The purpose of this study was to explore whether ablation undertaken from both the inside (endocardial) surface and the outside (epicardial) surface of the heart during the same procedure resulted in a higher chance of full thickness ablation, and a lower chance of having recurrence of AF or other heart rhythms from the top chambers of the heart (atria).
All of the patients that were recruited to this study had undergone at least one previous AF ablation but had recurrence of persistent AF. The main measure that was looked at to determine the success of the endocardial-epicardial ablation technique was the time to recurrence of AF following treatment. Other measures were also reviewed, and included adverse effects, and assessing the participants experience of their condition using the Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire.
Statistical analysis was not undertaken to determine the number of patients that would be required to undergo the procedure as this study was a safety and feasibility pilot study in preparation for a randomised controlled trial, dependent on the outcome from this trial.
Results
A total of 20 patients were recruited to the trial. Epicardial access was successful in all patients, however in 1 patient we were not able to access all areas required in the outside surface of the heart. This prevented full thickness ablation in one area of the heart in 1 patient. Of the 20 patient, 60 lines of ablation were undertaken, termed linear ablation. Successful linear ablation is defined as the line being “blocked,” meaning that electrical activation is not able to pass across the line from one side to the other. Of the 60 lines of ablation, 58 (97%) were successfully blocked. Therefore, there was a 97% success rate in stopping the errant signals that can cause AF.
Three different lines were ablated (scar lines), and included a roof line, inferior line, and anterior mitral line, which relate to the position of the scars made within the heart. Of the 20 roof lines, 55% of these lines required additional ablation on the outside surface of the heart in addition to ablation on the inside surface of the heart in order to block the line. Of the 20 inferior lines, we were not able to access the outside surface in this area due to the anatomy in 1 patient, and 20% of patients required additional ablation on the outside surface of the heart to block the line. Of the 20 anterior mitral lines, 80% required additional ablation to the outside surface of the heart in order to block the line. At one-year follow up after the procedure, recurrence of AF was just 20%.
One patient suffered a serious adverse event following the procedure, in which a drain needed to be inserted into the outside space of the heart 4 hours after the procedure due to bleeding. The bleeding resolved without and further intervention. This resulted in an increased length of hospital admission, and also resulted in inflammation and pain in the outside surface of the heart (pericarditis). This was treated with pain control medications, and completely resolved while the patient was back in the community. No other complications were observed.
Conclusion
This study demonstrated that ablation using an endocardial-epicardial approach to treat AF is safe and technically feasible. Success rates in achieving block across lines of ablation is much higher when using this approach, and recurrence of AF is much lower. The advantage of this procedure is the higher rate of success, and lower likelihood of requiring multiple procedures.REC name
East of England - Cambridge East Research Ethics Committee
REC reference
20/EE/0178
Date of REC Opinion
21 Aug 2020
REC opinion
Further Information Favourable Opinion