Magneto-SCD
Research type
Research Study
Full title
A multi-centre observational cohort study to identify Magentocardiography (MCG) parameters in the prediction of future ICD therapy.
IRAS ID
254466
Contact name
Faizel Osman
Contact email
Sponsor organisation
University Hospital Coventry and Warwickshire
Duration of Study in the UK
6 years, 8 months, 3 days
Research summary
Research Summary:
To investigate the ability of a prototype, portable bedside unshielded magnetometer to predict future arrhythmias associated with sudden cardiac death in patients who meet current NICE criteria for Implantable Cardioverter Defibrillator implantation.
Sudden cardiac death accounts for over 4 million deaths per year globally. The only effective preventative treatment for this the implantable cardioverter defibrillator - a small pacemaker like device that can halt dangerous heart rhythms. However, identifying those patients at risk of sudden cardiac death has proved difficult with current guidelines relying on overall cardiac function and patient symptoms to determine eligibility for a device. We understand that a feature of sudden cardiac death risk is the presence of abnormal conduction in the heart muscle which creates substrate for the development of reentrant circuits of electrical activity. This then causes heart beats to be unregulated and ineffective at producing output from the heart and can rapidly escalate to death.
Magnetocardiography (MCG) has been suggested as a way of measuring these areas of abnormal conduction and reentrant circuits as it is able to measure the magnetic field associated with the electrical conduction within the heart with spatial separation that electrocardiography (ECG) cannot. This research has previously been limited to a small number of research centres due to the cost of installation and operation of specialist sensors and magnetically shielded rooms. However, a novel prototype portable magnetometer has been developed to work in an unshielded environment. It is hoped that using this we can screen larger numbers of patients and detect differences in the MCGs in those patients who are at higher risk of the arrhythmias leading to sudden cardiac death.
Summary of Results:
Why this study was done Implantable cardioverter-defibrillators (ICDs) can treat life-threatening heart rhythm disturbances, but many people who receive an ICD never go on to need it. This study explored whether a non-invasive test called magnetocardiography (MCG), which detects very small magnetic signals produced by the heart’s electrical activity, could help identify, at the time of implant, which patients are more likely to later need ICD treatment.
Who took part and what was measured
• 104 patients due to receive a new ICD (or Cardiac Resynchronisation Therapy with a Defibrillator (CRT-D)) were enrolled across 5 UK hospitals.
• 90 patients had MCG scans good enough to analyse.
• Patients were followed for about 3 years on average.
• The primary outcome was whether a patient later received appropriate ICD therapy, meaning the ICD delivered treatment (anti-tachycardia pacing and/or a shock) for a genuinely dangerous heart rhythm.Primary outcome result
When the researchers compared baseline MCG recordings, they found that two MCG measures were higher in patients who later went on to receive appropriate ICD therapy than in those who did not:
• Rotation Score (RS): higher in the group that later received ICD therapy (median 504.4) compared with the group that did not (median 331.7).
• Angular Dynamics (AD): also higher in the therapy group (median 3.264) than the no-therapy group (median 2.497).Looking at how outcomes unfolded over time, patients with higher Rotation Score or Angular Dynamics at the baseline scan were more likely to go on to receive appropriate ICD treatment during follow-up. In the study’s analysis, a typical step up (one standard deviation) in Rotation Score or Angular Dynamics was linked to roughly a doubling in the rate of receiving appropriate ICD therapy over time.
What that suggests
These findings indicate that, even before any ICD treatment occurred, patients who later needed ICD therapy tended to show more abnormal/complex electrical activation patterns on MCG (as captured by RS and AD). In practical terms, MCG may be able to detect a signal of higher future rhythm risk in some ICD recipients and therefore may be used to help better identify those patients most in need for ICDs.Important limitations to keep in mind
• This was a moderate-sized study and the number of patients who experienced the primary outcome was limited, which means results are more uncertain and need confirmation.
• Some scans could not be analysed due to interference, which may affect how easily this test could be used in all settings.
• The work is best viewed as promising early evidence, not yet something that should change patient care on its own.Bottom line
In this study, MCG measures (Rotation Score and Angular Dynamics) were higher at baseline in patients who later received appropriate ICD therapy, suggesting MCG could help with future risk assessment, but larger studies are needed to confirm reliability and clinical usefulness.REC name
Yorkshire & The Humber - Sheffield Research Ethics Committee
REC reference
19/YH/0143
Date of REC Opinion
4 Jul 2019
REC opinion
Further Information Favourable Opinion