Utilising clinical and electroanatomic mapping data to understand and treat persistent atrial fibrillation

Atrial fibrillation (AF) is a common heart rhythm problem affecting over 1.5 million people in the United Kingdom and is associated with an increased risk of stroke, heart disease and death. The condition is defined according to the duration of AF episodes with paroxysmal episodes lasting 7 days. AF can be treated using a procedure called ablation where parts of the heart which may cause AF are cauterised. This creates scar tissue, which doesn't conduct electricity, and aims to interrupt abnormal electrical circuits that may cause AF. The procedure may reduce symptoms and improve quality-of-life. Unfortunately, the procedure is only successful in 40-85% of patients and is less successful in patients with persistent AF. A repeat ablation can be performed when the initial procedure has been unsuccessful. However, repeat ablations themselves are unsuccessful in around 25-45% of patients. The reasons why the procedure works in some patients but not others are unknown but may be due to differences in the way in which AF develops and progresses amongst individuals.

During ablation procedures, large amounts of data known as electroanatomic mapping data are acquired. These data, which are related to individual patients' heart shape and function, may allow us to understand the range of different disease states that exist amongst patients with AF. This may help us understand why some patients respond to ablation procedures whereas others do not.

Aims and objectives

The aim of the study will be to use electroanatomic mapping data to understand the range of different disease states that exist amongst patients who have been uniformly classified as persistent AF. This information, which is acquired during the first ablation procedure, will be used to determine how patients may respond to a repeat procedure. Below three main objectives are described:

Define subgroups of persistent AF patients based on atrial properties.

Understand the mechanisms which initiate and maintain persistent AF in individual patients.

Use data from the first ablation procedure to predict response to a repeat procedure.

Potential applications and benefits

We aim to create practical tools that can predict how well a second ablation will work based on the results of the first one. This will help patients by making sure that those who undergo a second procedure are more likely to benefit from it. The tools will also help clinicians in determining which patients would benefit from repeat procedures. A reduction in potentially unnecessary ablation procedures, which cost >£7000 per procedure, will also have a positive impact on catheter laboratory waiting list times and costs.

Previous research developments using electroanatomic mapping data have been limited by the fact that the data are manufacturer-specific and difficult to retrieve. To address this issue, our group has developed OpenEP, a freely available tool capable of enabling the storage and analysis of electroanatomic mapping data in a standardised format, making it efficient in terms of computer storage. Within this study, we will use OpenEP to conduct an analysis of clinical and electroanatomic mapping data from patients with persistent AF. The use of OpenEP as a platform will facilitate further large-scale analyses of electroanatomic mapping data enabling these data to be used to improve the care of patients with heart rhythm problems.