IdeNtification of SPecific EleCTrophenotypes in Atrial Fibrillation
Conditions: Atrial Fibrillation
Sponsor: Imperial College London

Research Governance and Integrity Team (RGIT) 
 
 
PHENOTYPE-AF Protocol. V1.0 XX/XX/2021 IRAS: 307933 
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IdeNtification of SPecific EleCTrophenotypes in Atrial Fibrillation – INSPECT-AF 
 
 
 
 
 
MAIN SPONSOR: Imperial College London 
FUNDERS: N/A 
STUDY COORDINATION CENTRE: Hammersmith Hospital 
 
IRAS Project ID: 307933 
REC reference: xxx 
 
 
V1.0 17-02-2022 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Study Management Group 
 
Chief Investigator: Dr Fu Siong Ng  
Co-investigators: Dr Arunashis Sau 
Study Management: Dr Fu Siong Ng 
Study Coordination Centre – Hammersmith Hospital 
 
For general queries, supply of study documentation, and collection of data, please 
contact: 
Study Coordinator: Arunashis Sau 
 
Address: 4th Floor ICTEM building, Hammersmith campus, Imperial College London, 
72 Du Cane Road, W12 0UQ 
 
 
 
 
 
 
Registration: GMC 7494542 
Tel:      N/A  
 
 
 
 
 
 
E-mail:  
as7909@imperial.ac.uk/a.sau@nhs.net 
Fax:      N/A 
 
 
 
 
 
 
Web address:  N/A     
 
 
Clinical Queries 

Research Governance and Integrity Team (RGIT) 
 
 
PHENOTYPE-AF Protocol. V1.0 XX/XX/2021 IRAS: 307933 
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Clinical queries should be directed to Dr Arunashis Sau who will direct the query to 
the appropriate person 
 
 
Sponsor 
 
Imperial College London is the main research Sponsor for this study.  For further 
information regarding the sponsorship conditions, please contact the Head of 
Regulatory Compliance at: 
 
 
 
Research Governance and Integrity Team (RGIT) 
Imperial College London and Imperial College Healthcare NHS Trust 
Room 215, Level 2, Medical School Building 
Norfolk Place 
London, W2 1PG 
Tel: 0207 594 9459/ 0207 594 1862 
http://www3.imperial.ac.uk/clinicalresearchgovernanceoffice  
 
Funder 
 
This study is funded by the British Heart Foundation Reference: FS/CRTF/21/24183 
 
This protocol describes the PHENOTYPE-AF study and provides information about 
procedures for entering participants. Every care was taken in its drafting, but corrections 
or amendments may be necessary. These will be circulated to investigators in the study.  
Problems relating to this study should be referred, in the first instance, to the Chief 
Investigator. 
 
This study will adhere to the principles outlined in the UK Policy Frame Work for Health 
and Social Care Research. It will be conducted in compliance with the protocol, the Data 
Protection Act and other regulatory requirements as appropriate.  
 
 

Research Governance and Integrity Team (RGIT) 
 
 
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Contents 
1. INTRODUCTION 
6 
1.1. Background 
6 
1.2. Rationale for current study 
7 
2. STUDY OBJECTIVES 
8 
3. STUDY DESIGN 
8 
3.1. Study outcome measures 
8 
3.2. Study protocol 
8 
4. PARTICIPANT ENTRY 
11 
4.1. Pre-registration evaluations 
11 
4.2. Inclusion criteria 
11 
4.3. Exclusion criteria 
11 
4.4. Withdrawal criteria 
12 
5. ADVERSE EVENTS 
12 
5.1. Definitions 
12 
5.2. Reporting procedures 
12 
5.2.1. Non-serious AEs 
12 
5.2.2. Serious AEs 
12 
5.2.3. Incidental Findings 
13 
6. ASSESSMENT AND FOLLOW-UP 
13 
7. STATISTICS AND DATA ANALYSIS 
13 
8. REGULATORY ISSUES 
15 
8.1. Ethics approval 
15 
8.2. Consent 
15 
8.3. Confidentiality 
16 
8.4. Indemnity 
16 
8.5. Sponsor 
16 
8.6. Funding 
16 
8.7. Audits 
16 
9. STUDY MANAGEMENT 
16 
10. PUBLICATION POLICY 
16 
11. References 
17 

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Glossary of Abbreviations 
 
Abbreviation 
Definition 
ECG 
Electrocardiogram 
AF 
Atrial fibrillation 
pAF 
Paroxysmal atrial fibrillation 
PsAF 
Persistent atrial fibrillation 
ECGI 
Electrocardiographic imaging 
DCCV 
Direct current cardioversion 
 
 
 
 
 
 
 
 
 
Keywords 
atrial fibrillation, ablation, electrophenotype, ECGI 

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Study summary 
 
TITLE Identification of specific electrophenotypes in human atrial fibrillation – 
INSPECT-AF 
 
DESIGN Single Centre, Observational Study  
AIMS 1. Investigate the range of AF electrophenotypes and mechanisms in human 
AF and identify the important functional, structural and clinical determinan
of the AF electrophenotype 
2. Develop the use of non-invasive modalities to classify the underlying AF 
electrophenotype 
OUTCOME 
MEASURES 
1. 
Freedom from AF 
2. 
AF burden 
3. 
Quality of life 
POPULATION Patients with atrial fibrillation due to undergo first time atrial fibrillation ablatio
or DCCV for under clinical grounds at Hammersmith Hospital  
ELIGIBILITY Adult patients 18-85 years, who are able to give informed consent,  
DURATION 4 years 
 
 
 

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1. INTRODUCTION 
1.1. Background 
Atrial fibrillation (AF) is the most common cardiac arrhythmia in adults(1), with an 
estimated prevalence of 1% and is projected to become more prevalent (2, 3). AF is 
also a significant source of morbidity and mortality (4, 5) as well as reduced quality of 
life and exercise capacity in patients with AF-related symptoms, which can be 
improved with maintenance of sinus rhythm (6). 
Limitations of current treatments and catheter ablation for AF 
Catheter ablation is a commonly used to aid maintenance of sinus rhythm. We 
recently reported that pulmonary vein isolation (PVI) is markedly more effective than 
strategies not incorporating PVI (7), and PVI therefore remains the cornerstone of AF 
ablation. In patients with paroxysmal AF (PAF), PVI reduces AF recurrence in 
around 70-80% of patients (8), however in persistent AF (PsAF) the success rate of 
ablation is only 50% (9). The atrial substrate is an important determinant of 
recurrence in PsAF, this may explain the relatively poor outcomes of a PVI-only 
ablation approach. A wide range of adjunctive ablation strategies have been studied, 
however we have shown none conclusively improve success rates (10).  
Lack of consensus on AF mechanisms - absence of mechanism-directed 
treatments 
One major issue limiting the success of treatments for PsAF is the lack of 
mechanism-directed therapies. Although PsAF appears to be a heterogenous entity, 
ablation strategies for persistent AF centre around PVI. Adjunctive strategies are 
largely empirical with no tailoring of strategy towards patient-specific mechanisms. 
The absence of mechanism-directed treatments is due partly to the lack of 
consensus on the electrophysiological mechanisms that sustain AF. Two broadly 
contradictory hypotheses have been put forward. The “anarchical” model of AF 
proposes that AF is sustained by multiple self-perpetuating activation wavelets 
propagating randomly until extinguished(11). Importantly, this model is based on an 
absence of localised sources and would be best treated by lines of block to confine 
and extinguish wavelets (12, 13). Conversely, the “hierarchical” model proposes that 
AF is sustained by localised drivers or ‘rotors’ that may be stable or dynamic (14-16) 
however multi-centre studies of rotor guided ablation has demonstrated this 
approach to be ineffective  (17, 18). 
 
Concept of spectrum of different ‘electrophenotypes’ of AF 
These apparently contradictory models may in fact prove to be a false dichotomy – 
the different proposed mechanisms may all be important in sustaining AF, with the 
predominant AF mechanism determined by the underlying atrial substrate. We 
recently described a spectrum of fibrillation ‘electrophenotypes’ in the ventricle (19), 
where patchy fibrosis favours VF sustained by stable rotational activity, while 
compact fibrosis is more prone to disorganised fibrillation with an intermediate 
electrophenotype caused be diffuse interstitial fibrosis. Our analysis of human 
persistent AF supports the hypothesis that a similar range of electrophenotypes 
exists in the atria (20). Figure 1 (reproduced from Ng et al (21)) depicts our 
hypothesised electrophenotype spectrum for PsAF, proposing different AF 
mechanisms depending on the underlying substrate. 
 
Mechanism-directed treatments based on identification of AF 

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electrophenotype 
If the electrophenotype spectrum exists for human PsAF, and if the AF 
phenotype/mechanism can be reliably identified and classified in individual patients, 
a mechanism-directed approach may yield better success rates for AF ablation. For 
example, organised AF may be treated by mapping drivers while disorganised AF 
may be better treated with compartmentalisation of the atria with linear lesions or 
avoidance of ablation altogether.  
 
Using non-invasive modalities to classify AF electrophenotype 
Although we have shown that the identification of AF electrophenotype is possible 
using intracardiac electrograms, it would be preferable if the AF electrophenotype 
can also be discerned using non-invasive modalities, such as the ECG, 
electrocardiographic imaging (ECGI) and cardiac magnetic resonance imaging 
(CMR), all of which contain some information on the electrical and structural 
remodelling in the atria, and with which we have significant experience. 
Surface ECG characteristics, including P wave duration and f-wave parameters have 
been used to predict success following catheter ablation and categorise AF (22-24).  
Because ECGI can provide detailed information in atrial conduction properties, it 
may also assist the classification of an individual’s AF electrophenotype. ECGI is a 
non-invasive method to map epicardial electrograms across both ventricles and atria 
using 252 electrodes on the patient’s chest and back (25).  
Lastly, CMR has been used to quantify LA fibrosis (26), and based on our groups 
work in VF showing the important role of fibrosis pattern on determining VF 
mechanism (19), LA fibrosis maps from CMR may therefore be useful in 
complementing ECG and ECGI in helping to classify an individual’s AF mechanism 
and electrophenotype. Our own analyses have described the distribution of scar 
within the left atrium and the effect of fibrosis on left atrial electrophysiological 
properties, with recent demonstrations that LA fibrosis as detected on CMR 
correlates with intracardiac electrograms voltage acquired in atrial fibrillation (27).  
Recurrence of atrial arrhythmia after AF ablation 
Current success rates following ablation for PsAF are only 50%. A significant 
proportion of these recurrences are due to the organised atrial arrhythmias atrial 
flutter and atrial tachycardia. Atrial flutter may be cavotricuspid isthmus (CTI) 
dependent or have a different mechanism. Ablation for CTI dependent flutter has a 
significantly higher success rate compared to ablation for atrial tachycardia. 
Additionally, knowledge of the tachycardia mechanism can be helpful to plan an 
ablation procedure; if the tachycardia originates in the right atrium the procedure can 
be undertaken under local anaesthetic without a transeptal puncture, while a left 
atrial tachycardia may require a general anaesthetic and transoesophageal 
echocardiography for transeptal puncture.  
Biomarkers for atrial fibrillation 
Proteomics profiling has been used to identify proteins independently associated 
with incident AF (28). MicroRNAs have similarly been associated with incident AF 
and cardiac remodelling (29).  Machine learning (ML) has been incorporated with 
proteomics to yield new insights and outperform traditional techniques (30). 
1.2. Rationale for current study 
1. 
In human AF, there is a spectrum of different AF mechanisms (manifest as a 

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spectrum of ‘electrophenotypes’) that can sustain AF 
2. 
The specific AF electrophenotype in each patient is determined by the 
underlying atrial substrate, and correlates to functional (e.g. conduction 
velocity), structural (fibrosis burden) and clinical characteristics (e.g. AF 
duration) 
3. 
Analysis of surface ECGs, 252 lead ECGs and scar maps from MRI, in 
isolation or in combination, can provide an accurate non-invasive 
classification of AF electrophenotype, when compared to the gold-standard 
classification using intracardiac electrograms 
4. 
Machine learning (ML) can be applied to ECGs, electrograms, 252 lead ECG 
and cardiac MRI to aid classification of electrophenotype 
2. STUDY OBJECTIVES 
Primary objectives 
1. 
Investigate the range of AF electrophenotypes and mechanisms in human AF 
and identify the important functional, structural and clinical determinants of the 
AF electrophenotype 
 
Secondary objectives 
2. 
Develop the use of non-invasive modalities such as the surface ECG, 252 
lead ECG and CMR, in isolation or in combination, to classify the underlying 
AF mechanism/electrophenotype 
3. STUDY DESIGN 
This is a prospective interventional study investigating invasive and non-invasive 
tools for determining AF electrophenotype. The study will last 2 years in duration and 
will recruit patients undergoing ablation or DCCV procedures for atrial fibrillation 
(AF). Patients will be recruited from secondary care clinics or pre-assessment prior 
to procedures at Hammersmith Hospital.  
 
 
The study will be run at a single centre at the Hammersmith Hospital, Imperial 
College Healthcare NHS Trust. We will aim to enrol 300 patients. 
3.1. Study outcome measures 
We will classify patients into electrophenotypes based on the invasive and non-
invasive data collected. The primary outcome measure will be freedom from AF. 
Secondary outcome measures will be AF burden and quality of life.  
3.2. Study protocol 
Patients that suffer from AF and have been put forward for an ablation or DCCV, on 
clinical grounds as per current guidelines, will be recruited. Patients will be 
approached by a member of the clinical team by telephone from the Hammersmith 
Hospital waiting lists to discuss their interest in participating in the study. If the 
patient is interested, they will be provided with a patient information sheet, detailing 
information with regards to the study. The Investigators will subsequently consult 
with these patients to explain the study in greater detail and answer any further 
questions, in person, during an outpatient clinic visit or by phone. The consent form 
will include all information about the study and the mapping procedure. 
 

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All patient clinical data will be collected on a standardised electronic case report 
form. 
 
Study groups 
Diagram summarising study subgroups: 
 
 
Biomarker protocol (all groups): 
All patients will have blood samples taken to investigate for biomarkers that may 
correlate with electrophenotypes. In most cases this will be taken during the same 
blood draw as blood tests taken for clinical care or from sheaths in central veins that 
are placed routinely during an AF ablation. Rarely it may be necessary to perform an 
additional venepuncture in order to obtain the samples.  
 
252 lead ECG protocol (green + orange groups): 
A subgroup of 50-100 patients with persistent AF will have a 252 lead ECG. This will 
consist of up to 252 electrodes attached to the patient’s front and back. A recording 
of up to 10 minutes will be taken before the AF ablation or DCCV procedure.  
 
MRI protocol (orange group): 
A subgroup of 10-30 patients who are undergoing ablation will undergo thoracic and 
cardiac MRI including administration of gadolinium intravenously. This will be 
performed on the day of their ablation procedure, prior to the ablation. This subgroup 
will have an additional 1-2 visits 1-2 weeks apart prior to their procedure date, where 
they will attend the hospital for 10 minutes of data collection with the 252 electrode 
device. This subgroup will have co-registration of the 252 electrode recordings taken 
on the day of the ablation with the MRI to allow reconstruction of the epicardial 
•
Biomarkers only
•
Biomarkers 
•
252 lead ECG
•
Biomarkers 
•
252 lead ECG (on 2-3 occasions) 
•
MRI
Patients with atrial fibrillation undergoing DCCV or ablation
Study population

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electrograms through the inverse solution and Tikhonov regularisation steps.  
 
DCCV protocol 
1. All patients will have up to 252 electrodes placed on their chest and 
back 2. Surface electrical data will be collected before the procedure and 
removed prior to the DCCV 
2. All patients will have sedation delivered by an Anaesthetist 
3. Up to 3 synchronised shocks will be delivered in accordance with routine 
clinical practice 
4. Patient recovery 
 
AF ablation protocol 
The AF ablation procedure will take place in the electrophysiology laboratory. The 
procedure routinely takes place under general anaesthetic. The procedure typically 
lasts 2-3 hours.  
 
1. All patients will have up to 252 electrodes placed on their chest and 
back, with gaps where necessary for patches/electrodes for clinical use 
2. Surface electrical data will be collected throughout the procedure from 
the multiple electrodes 
3. A subgroup of patients will have thoracic and cardiac MRI with 
gadolinium contrast 
4. All patients will be out under general anaesthetic by a Consultant 
Anaesthetist. 
5. All patients will have a Transoesophageal echocardiogram to exclude LAA 
thrombus. 
6. All patients have sheaths (small plastic tubes) inserted through their groin 
veins (femoral veins).  
7. A transseptal puncture will be performed to gain access to the left atrium 
under heparin cover. 
8. Cardiac ablation and mapping catheters (small plastic tubes with electrodes at 
the end) are advanced into the heart under fluoroscopic guidance. 
9. A 3D model of the heart will be created to help guide ablation using clinical 
software (Ensite Precision, Abbott UK or CARTO, Biosense Webster). 
10. Electrical mapping data will be collected while the patient is in AF using 
a dedicated mapping catheter (Lasso or AFocusII/HD grid) 
11. Adenosine will be administered through a central venous sheath to 
induce transient AV block, during which surface electrical data will be 
collected 
12. Pulmonary Vein Isolation ablation with radiofrequency energy  will be 
completed as per standard of care. 
13. Electrical mapping data will be collected after pulmonary vein isolation if 
the patient has remained in AF.  
14. All patients will be cardioverted as part of the standard of care. 
15. Heparin reversal with Protamine. 
16. Sheath removal 
17. End of procedure 
18. Patient recovery 
 
Steps in bold above will be additional to the standard of care. 

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After the procedure has finished and all devices have been removed from the 
patient, we will export each patient’s pseudonymised data for further offline analysis  
 
Patients undergoing AF ablation will be provided with an AliveCor device to use up to 
once per day and when they have symptoms to accurately monitor for recurrence of 
AF. They will also have holter monitoring and clinical follow up in line with routine 
clinical care. Patient’s will be asked to complete symptom score/quality of life 
questionnaires up to once per month during follow up. 
 
Patients undergoing DCCV will be followed as per routine clinical care. 
 
Study participation will conclude after 300 patients have been recruited. Patients will 
be able to leave the study at any time they wish; they need only inform the research 
team. 
 
 
4. PARTICIPANT ENTRY 
4.1. Pre-registration evaluations 
All patients enrolled in this study will have the usual standard of care NHS pre-
procedural assessment for an ablation or DCCV for Atrial Fibrillation. 
 
4.2. Inclusion criteria 
Patients with atrial Fibrillation that have been put forward for an ablation or DCCV 
based on clinical grounds. 
• 
Suitable candidate for catheter mapping/ablation or direct current 
cardioversion for atrial fibrillation  
• 
Eighteen (18) to eighty-five (85) years of age 
• 
Able to give informed consent  
4.3. Exclusion criteria 
• 
Severe cerebrovascular disease 
• 
Moderate to severe renal impairment (eGFR < 30) 
• 
Active gastrointestinal bleeding 
• 
Active infection or fever 
• 
Short life expectancy 
• 
Significant anaemia 
• 
Severe uncontrolled systemic hypertension 
• 
Severe electrolyte imbalance 
• 
Congestive heart failure - NYHA Class IV 
• 
Recent myocardial infarction 
• 
Bleeding or clotting disorders 
• 
Paroxysmal Atrial Fibrillation 
• 
Uncontrolled diabetes 
• 
Inability to receive IV or oral Anticoagulants 
• 
Unable to give informed consent (these patients would not be recruited) 

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• 
Pregnancy 
 
4.4. Withdrawal criteria 
• 
One of the exclusion criteria are fulfilled during the study period 
• 
Patient wishes to withdraw from study 
 
If criteria are fulfilled for exclusion during the study period patient will be withdrawn 
by investigators. 
 
If patient wishes to withdraw, they can inform any staff involved in the study in writing 
or in person or any other mode of communication, and they will be withdrawn.  
 
In call cases of withdrawal data will be kept and used in the study up to the time of 
withdrawal.  
 
 
5. ADVERSE EVENTS 
5.1. Definitions 
Adverse Event (AE): any untoward medical occurrence in a patient or clinical study 
subject.   
 
Serious Adverse Event (SAE): any untoward and unexpected medical occurrence or 
effect that: 
• 
Results in death 
• 
Is life-threatening – refers to an event in which the subject was at risk of death 
at the time of the event; it does not refer to an event which hypothetically might 
have caused death if it were more severe 
• 
Requires hospitalisation, or prolongation of existing inpatients’ 
hospitalisation 
• 
Results in persistent or significant disability or incapacity 
• 
Is a congenital anomaly or birth defect 
 
Medical judgement should be exercised in deciding whether an AE is serious in other 
situations.  Important AEs that are not immediately life-threatening or do not result in 
death or hospitalisation but may jeopardise the subject or may require intervention to 
prevent one of the other outcomes listed in the definition above, should also be 
considered serious. 
5.2. Reporting procedures 
All adverse events should be reported.  Depending on the nature of the event the 
reporting procedures below should be followed.  Any questions concerning adverse 
event reporting should be directed to the Chief Investigator in the first instance. 
5.2.1. Non-serious AEs  
All such events, whether expected or not, should be recorded. 
5.2.2. Serious AEs  

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An SAE form should be completed and faxed to the Chief Investigator within 24 hours.  
However, recurrence of or death related to neurocardiogenic syncope, and 
hospitalisations for elective treatment of a pre-existing condition do not need reporting 
as SAEs. 
 
All SAEs should be reported to the to the [Placeholder for Ethics Committee] 
where in the opinion of the Chief Investigator, the event was: 
• 
‘related’, i.e. resulted from the administration of any of the research 
procedures; and 
• 
‘unexpected’, i.e. an event that is not listed in the protocol as an expected 
occurrence 
 
Reports of related and unexpected SAEs should be submitted within 15 days of the 
Chief Investigator becoming aware of the event, using the NRES SAE form for non-
IMP studies. The Chief Investigator must also notify the Sponsor of all related and 
unexpected SAEs. 
 
Local investigators should report any SAEs as required by their Local Research Ethics 
Committee, Sponsor and/or Research & Development Office. 
 
Contact details for reporting SAEs: 
Please send SAE forms to: Dr Arunashis Sau: a.sau@nhs.net, Dr Fu Siong Ng: 
fusiong.ng@nhs.net and Imperial research governance and integrity 
RGIT@imperial.ac.uk  
 
5.2.3. Incidental Findings  
In the event an incidental finding is uncovered during the study, the relevant clinical 
team will be immediately notified. We will also inform the patient’s GP, with the 
patient’s permission (relevant clause is present on the informed consent form). 
 
6. ASSESSMENT AND FOLLOW-UP 
Patients undergoing AF ablation and the 252 lead ECG protocol will be provided with 
an AliveCor device to use up to once per day and when they have symptoms to 
accurately monitor for recurrence of AF. They will also be asked to complete 
symptom score (36-Item Short Form Survey Instrument  
(SF-36) and Atrial Fibrillation Effect on QualiTy-of-life (AFEQT)) questionnaires up to 
once per month. They will have Holter monitoring and clinical follow up in line with 
routine clinical care.  
 
Patients undergoing DCCV will be followed as per routine clinical care for 1 year. 
 
The end of study is when the last patient has completed their last follow up visit.  
7. STATISTICS AND DATA ANALYSIS 
We will use the data collected to investigate the specific determinants of AF 
mechanism and electrophenotype. Patients will be classified into a range of AF 
mechanisms and electrophenotypes, ranging from organised AF sustained by 
localised drivers through to disorganised AF. The specific functional (e.g. atrial 

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conduction properties), structural (e.g. left atrial fibrosis burden) and clinical (e.g. AF 
duration) determinants of the AF electrophenotype will be investigated.  
Intracardiac EGM data and 252 lead ECG 
The 252 electrode device data will be analysed using a combination of established 
signal processing (dominant frequency, phase mapping and Shannon entropy) and 
machine learning techniques (unsupervised learning to cluster data into distinct 
phenogroups. For the subset of 10 patients with MRI data, we apply our ‘in house’ 
inverse solution and Tikhonov regularisation steps to reconstruct the epicardial 
electrograms.  
 
Cardiac MRI 
I will analyse burden of fibrosis and fibrosis distribution patterns and correlate these 
with the electrogram data.  
 
AF electrophenotype will be determined using the analyses above. I will characterise 
each patient using both a regional and a global approach. The regional approach will 
analyse each sequentially collected ‘kernel’ of data from the RA and LA and assign a 
metric of organisation. The electrophenotype of a single patient therefore will be 
described by the number of organised/disorganised sites. The global approach will 
assign a global metric of organisation, including data from all collected kernels from 
both RA and LA. I will investigate the determinants of electrophenotype by 
correlating electrophenotype with clinical parameters including AF duration, co-
morbidities and left atrial size on echocardiography. I will also compare intracardiac 
mapping pre- and post- PVI to investigate the impact of PVI on AF electrophenotype. 
I will investigate the degree to which the AF electrophenotype can predict outcomes 
compared to conventional clinical and echocardiographic predictors.  
 
Biomarkers for identification of AF electrophenotype 
We will look for differences in lipid metabolite levels, miRNA and protein expression 
between the electrophenotype groups, which may serve as biomarkers to non-
invasively distinguish between these groups. I will analyse human serum using DNA 
barcode technology integrated with a nanopore platform to measure levels of these 
circulating miRNAs and proteins. Machine learning has been used effectively in 
proteomic studies (30). I aim to apply the biomarker data with electrical and imaging 
data using unsupervised machine learning to identify clinically relevant clusters 
(phenotypes).  
 
Developing non-invasive methods to classify AF electrophenotype  
Using simultaneously collected 252 lead ECG and intracardiac data, together with 
CMR LA fibrosis data, the surface ECG and biomarkers, I will develop tools to non-
invasively classify AF electrophenotype.  
Using the intracardiac data as the gold standard, I will continue to develop tools to 
determine the degree of global fibrillation organisation from surface ECGs, using 
band-power feature analysis and machine learning techniques. 252 lead ECG-
derived biatrial maps in atrial fibrillation will then be analysed using both established 
(dominant frequency, phase mapping and Shannon entropy) and the novel (ML 
based analysis, including unsupervised machine learning) to further stratify patients 
into a spectrum of organised to disorganised electrophenotypes. Simultaneous 

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intracardiac and 252 lead ECG recordings will also allow further validation of 252 
lead ECG in atrial fibrillation. I will use CMR data to correlate electrophenotype with 
anatomical data. LA fibrosis will be categorised by both degree and distribution of 
fibrosis and correlated with both intracardiac and non-invasively acquired 
electroanatomical data using linear regression models and ML. Invasive and non-
invasive parameters will be combined and correlated with AF recurrence to create a 
tool using only non-invasive data to determine a patient-specific electrophenotype.  
 
Outcomes 
Freedom from AF, AF burden and quality of life outcome data will be correlated with 
electrophenotype groups (as defined by the above analyses) to investigate if certain 
groups benefit more from ablation than others. 
 
Sample size is based on collecting sufficient data to detect differences in 
electrophenotypes using biomarkers and ECG parameters. 
 
Data will be analysed by the chief investigator and the research team at the National 
Heart and Lung Institute, Imperial College London.  
 
Data and all appropriate documentation will be stored for a minimum of 10 years 
after the completion of the study, including the follow-up period.   
8. REGULATORY ISSUES 
 
 
8.1. Ethics approval  
The Study Coordination Centre has obtained approval from Health Regulator Authority 
(HRA). The study must also receive confirmation of capacity and capability from each 
participating NHS Trust before accepting participants into the study or any research 
activity is carried out. The study will be conducted in accordance with the 
recommendations for physicians involved in research on human subjects adopted by 
the 18th World Medical Assembly, Helsinki 1964 and later revisions. 
 
An approval from the National Research Ethics Committee (NRES) will be obtained 
before the start of any study related procedure and other relevant documents. All 
correspondence with the NRES will be retained in the Study Files. 
8.2. Consent 
Consent to enter the study must be sought from each participant only after a full 
explanation has been given, an information leaflet offered, and time allowed for 
consideration.  Signed participant consent should be obtained.  We will gain consent 
for participation in the study at Hammersmith Hospital. Consent for participation in the 
study can be gained by a consultant or registrar who is familiar with the study, clinical 
research fellow, or study nurse. Consent for the ablation procedure will be gained on 
the day of the procedure by the consultant performing the ablation or a specialty 
registrar who is familiar with the procedure, following normal clinical practice.  
The right of the participant to refuse to participate without giving reasons must be 
respected.  After the participant has entered the study the clinician remains free to 

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give alternative treatment to that specified in the protocol at any stage if he/she feels 
it is in the participant’s best interest, but the reasons for doing so should be recorded.  
In these cases, the participants remain within the study for the purposes of follow-up 
and data analysis.  All participants are free to withdraw at any time from the protocol 
treatment without giving reasons and without prejudicing further treatment. 
In case of loss of capacity during the study period, the participant will be withdrawn 
from the study. Identifiable data or tissue already collected with consent would be 
retained and used in the study. No further data or tissue will be collected, or any other 
research procedures carried out on or in relation to the participant. We will ensure 
informed consent is gained for use of collected data in case of incapacity, at a time 
when the patient has the capacity to make this decision. 
8.3. Confidentiality 
The Chief Investigator will preserve the confidentiality of participants taking part in the 
study and is registered under the Data Protection Act. 
 
Data will be pseudonymised  
 
8.4. Indemnity 
Imperial College London holds negligent harm and non-negligent harm insurance 
policies which apply to this study. 
8.5. Sponsor 
Imperial College London will act as the main Sponsor for this study.  Delegated 
responsibilities will be assigned to the NHS trust taking part in this study. 
8.6. Funding 
This study is funded by the British Heart Foundation Reference: FS/CRTF/21/24183 
 
There will be no payments to research participants or researchers. 
8.7. Audits 
The study may be subject to inspection and audit by Imperial College London under 
their remit as sponsor and other regulatory bodies to ensure adherence to GCP and 
the UK Policy Frame Work for Health and Social Care Research.  
9. STUDY MANAGEMENT 
 
The day-to-day management of the study will be coordinated by Dr Arunashis Sau 
clinical research fellow.  
 
10. PUBLICATION POLICY 
The investigators will publish the findings of the study at conference presentations 
and in peer-reviewed journals. 
 
 

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11. References 
 
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17. 
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