PREDICTive value of non-invasive surface ECG mapping of ATRIAL SUBSTRATE in atrial arrythmia patients: The PREDICT ATRIAL SUBSTRATE study

A 252-electrode surface ECG mapping vest will be applied with an electro-anatomic map of the atria compiled after merging data with a cardiac CT scan. This will be compared to standard invasive electro-anatomic mapping data collected during routine electrophysiology study and ablation. The surface ECG vest will be fitted by trained study personnel (cardiac scientists, nurses, doctors) on a single occasion as per the product sizing and fitting guidelines. A cardiac CT scan will be performed once, (generally <30 minutes) with the vest worn, on the same day. Where there is a clinical indication for concomitant coronary artery assessment, iodinated contrast will be administered with the CT scan, in the same fashion and dose as would have been performed in the participant outside of this clinical study. The estimated dose of iodinated contrast for coronary assessment, if indicated, is 80-100mL. Data-merge with the CT scan and electrical data from the vest will take place over the next 1-2 hours, or less. Participants will be selected from patients referred for electrophysiology study +/- ablation for atrial fibrillation or supraventricular tachycardia. Participants will undergo their clinically indicated electrophysiology study and ablation procedure, which does not differ in this study to standard practice. This study takes place in the cardiac electrophysiology laboratory and involves procedural sedation or general anaesthetic, with local anaesthetic to the right groin, where the procedural doctor will place sheaths, and through these sheaths, small catheters with electrodes on them. These catheters will be moved up to the heart and a puncture of the septum between the right and left upper chambers (atria) will be made, followed by passage of catheters to the left atrium. A dose of blood thinner (heparin) is routinely given at the point of crossing from the right to the left atrium. Mapping catheters will be passed into the left atrium and moved into contact with the atrial surface to collect the location in space and the voltage at the surface, which gives an indication of the health of the atrial muscle tissue. After electro-anatomic mapping has been performed, ablation will be performed using radio frequency energy to 'cauterise' specific areas of the atria. The ablation will vary depending on what rhythm is being treated and where the circuit is identified, but in general in atrial fibrillation involves a ring encompassing the pulmonary veins and part or all of the posterior atrial wall to electrically isolate these from the rest of the atria, and for supraventricular tachycardias, a smaller area of ablation is required to treat a focal source of the problem, or an area of slowly-conducting tissue or extra muscular connection that can be safely ablated to stop a circuit responsible for the rhythm problem. Atrial fibrillation or supraventricular tachycardia procedures including standard 3-dimensional electro-anatomic mapping utilising mapping catheters inside the heart and ablation will usually take between 1.5 and 2.5 hours to complete. The main difference from standard procedure for these arrhythmias in this study is that the pre-fitted surface mapping vest will be worn during the procedure. After the procedure, the vest will be removed and the data from the electro-anatomic mapping and surface ECG mapping will be processed and compared offline. Participation in the study including the vest fitting, CT scan, electrophysiology study and ablation procedure will occur over around 5 hours on the same day.