Atrial Fibrillation Substrate Assessment Using Exercise-ECGI
Research type
Research Study
Full title
Non-Invasive Atrial Fibrillation Substrate Assessment Using Exercise-Electrocardiographic Imaging
IRAS ID
241295
Contact name
E Williams
Contact email
Sponsor organisation
King's College London
Duration of Study in the UK
1 years, 11 months, 26 days
Research summary
Research Summary
The project will develop a new diagnostic tool for patients with atrial fibrillation (AF). AF is the most common sustained heart rhythm disorder and occurs due to electrical abnormalities in the top chambers of the heart (the right and left atria). Currently, the only method for assessing these changes relies on invasive catheter recordings where wires are placed into the heart via a large vein at the top of the leg. International guidelines recommend catheter ablation for the treatment of atrial fibrillation when patients have ongoing symptoms despite the use of anti-arrhythmic drugs. The procedure is successful in some, but not all patients, and patients with more significant electrical changes have worse outcomes than those without these changes.
We believe that non-invasively studying these atrial electrical changes could lead to improvements in patient selection for catheter ablation procedures and therefore lead to the procedure being avoided in patients in whom success is unlikely. Importantly, we have recently published data showing that not all these electrical changes are observable at resting heart rates. This project will therefore investigate the feasibility of using electrocardiographic imaging (ECGI) to perform an 'electrical stress test' by non-invasively assessing changes in electrical conduction occurring during exercise.
We will recruit 5 healthy volunteers in order to configure the ECGI system for recording electrical changes during exercise. These volunteers will undergo an MRI scan whilst attached to the ECGI system and using a bicycle ergometer to simulate exercise. Following this we will recruit 20 patients with AF who are scheduled for catheter ablation. On the day of ablation, Exercise-ECGI will be performed in our combined MRI and cardiac procedure suite. Invasive assessment of atrial conduction will subsequently be performed in all patients during their AF ablation procedure and prior to delivery of ablation. ECGI recording will continue to happen during these measurements.
The electrical data from the ECGI will be compared to that from invasive measurements and in doing so we will determine whether ECGI can correctly identify the electrical changes in the atria known to be important to atrial fibrillation.
Summary of Results
This study investigated a novel method to assess conduction velocity, a fundamental property of atrial tissue, using exercise electrocardiographic imaging combined with cardiac MRI. By exercising using a recumbent cycle ergometer, five healthy volunteers achieved heart rates up to 150bpm. During exercise, electrograms from multiple electrodes encircling the thorax were taken at 5 different time points. The surface electrograms were then projected onto an anatomical representation of the atria obtained with MRI. The conduction velocity at all varying heart rates was calculated off-line using previously described methods. Calculation of bi-atrial conduction velocity was possible, and the velocities from this study fall within previous published ranges of atrial conduction velocity. There was no difference in conduction velocity between varying heart rates. The results show successful development of a method to measure atrial conduction velocity at varying heart rates. Future work is required to determine the accuracy and clinical application of this method.
REC name
West of Scotland REC 5
REC reference
19/WS/0060
Date of REC Opinion
24 Apr 2019
REC opinion
Favourable Opinion