Brief Title
Using Ripple Mapping to Guide Substrate Ablation of Scar Related Ventricular Tachycardia.
Official Title
Determining the Pathophysiological Role of Slow Conduction Channels Identified by Ripple Mapping of the Ventricular Scar.
Brief Summary
The heart beat is controlled by electrical signals. Following a heart attack, part of the
heart muscle dies and is later replaced by scar tissue. Within this area of scar, there often
remain "channels" of surviving tissue still able to transmit electrical signals. However, it
is well established that these "conduction channels" (CC) can form a short circuit around the
scar, leading to electrical disturbances (arrhythmias) that are potentially life threatening.
The commonest of these is ventricular tachycardia (VT), and is estimated to cause 300,000
deaths per year.
One recognised treatment option of VT involves burning (ablation) these "conduction channels"
(CC) within the scar. However, at present, the procedure is long and is far off 100%
effective. Consequently, current best practice does not rely on treating the VT, but rather
preventing it from causing sudden death - this is achieved with an Implantable Cardioverter
Defibrillator (ICD), a device which can recognise when a patient is in VT and deliver an
internal shock to restore the normal electrical conduction. Patients with defibrillators
subsequently are subject to recurrent painful and debilitating shocks which, although
lifesaving, significantly reduce their quality of life. The limitation with ablation at
present is due to the difficulty in visualising these CC's.
Investigators at Imperial College have created a novel electrogram visualisation program,
Ripple Mapping (RM), which they have already found to be superior to currently used
programmes in cases of arrhythmias in the upper chambers of the heart (the atria). During a
retrospective study in patients with scar related VT following a heart attack, when ablation
was delivered in areas associated with identified Ripple Mapping Conduction Channels, these
patients remained free of VT recurrence for >2 year follow up interval.
The study hypothesis is that Ripple Mapping can identify all conduction channels within scar
tissue critical to the VT circuit, ablation of which will lead to long-term freedom from VT
and ICD therapies. The investigators now aim to perform a prospective randomised study
comparing Ripple Mapping guided VT ablation against conventional VT ablation.
Detailed Description
In patients with a previous heart attack, the scar formed in the left ventricle (bottom
chamber of the heart) consists of dead tissue mixed with strands of live tissue which form
"conduction channels" (CC's). These Conduction channels can cause dangerous heart rhythms
such as Ventricular Tachycardia (VT). This can lead to symptoms such as shortness of breath,
dizziness, blackouts, and, in some, sudden death.
Patients at risk of sudden death receive special implanted devices called implantable
cardioverter defibrillators (ICD) and can present with recurrent painful and debilitating ICD
therapies consisting of internal shocks. Patients experiencing frequent ICD shocks due
recurrent VT usually undergo a procedure to burn (ablate) the area of scar within the heart
thought to be the source of the VT. This involves catheters (plastic tubes) inserted into the
heart via the groin vessels allowing the cardiac electrophysiologists to obtain information
about the scar. Scar tissue has low electrical voltage. By measuring the electrical voltage
of the tissue in the heart, areas of scar as well as areas of live, healthy tissue can be
identified and mapped. By burning (ablation) these abnormal channels of live tissue within
scar (conduction channels), this can effectively reduce the episodes of VT a patient
experiences, thereby reducing the frequency of shocks they experience and improve their
quality of life.
In any one patient, more than 1 conduction channel and hence source of VT can be found.
Current mapping technologies are incapable of providing electrophysiologists with the
information that is required to locate all these conduction channels. Therefore ablation
strategies have shifted from ablating in a single location in the scar, to extensive ablation
within the scar in the hope that ALL conduction channels will be burnt. However, this
extensive ablation strategy has no globally agreed consensus with several techniques used
worldwide.
The disadvantage of this extensive ablation strategy is that the potential regions which can
be responsible for VT can be large, requiring extensive ablation and therefore prolonged
procedure times in sick patients who are unable to tolerate such lengthy procedures. In its
current state, VT ablation by any strategy is technically challenging and time consuming with
procedural times as long as 8 hours. In addition, although acute procedural success ranges
from 77% to 95%, recurrence rates remain high - up to 50%.
Therefore, identification of ALL conduction channels within scar is a desirable goal for
catheter ablation therapy in VT. Ripple Mapping (RM) is a novel mapping program which allows
simultaneous display of "voltage" and "activation" data of the underlying ventricular tissue.
RM therefore has the potential to display more detailed information of the functional
properties of the underlying scar including any interspersed live tissue channels.
Investigators at Imperial College have demonstrated the proof of concept of RM and validated
the program in a series of abnormal heart rhythms that arise within the upper heart chambers
(the atria) where RM was found to have a superior diagnostic yield as well as aiding the
operator in reaching a diagnosis in shorter time when compared with conventional mapping
systems. The Investigators subsequently performed a retrospective analysis of 21 patients
undergoing post infarct VT ablation. All documented locations with concealed entrainment or
perfect pace matches to the induced or clinical VT coincided with Ripple Mapping Conduction
Channels (RMCC). In patients where ablation lesions overlapped all identified RMCCs, these
patients remained free of VT recurrence for >2 year follow up interval.
The Investigators therefore propose to study the hypothesis that Ripple Mapping can identify
all conduction channels within scar tissue critical to the VT circuit, ablation of which will
lead to long-term freedom from VT and ICD therapies. This will be determined via a
prospective randomised study comparing Ripple Mapping guided VT ablation against conventional
VT ablation.
Study Type
Interventional
Primary Outcome
Time to first appropriate ICD therapy
Secondary Outcome
Total appropriate ICD episodes
Condition
Monomorphic Ventricular Tachycardia
Intervention
Ripple Mapping guided VT ablation
Study Arms / Comparison Groups
Ripple Mapping guided VT ablation
Description: Ripple Mapping (Imperial College) software (Biosense Webster) will be used to identify conduction channels within the ventricular scar substrate to guide ablation lesions in patients with monomorphic VT.
Publications
* Includes publications given by the data provider as well as publications identified by National Clinical Trials Identifier (NCT ID) in Medline.
Recruitment Information
Recruitment Status
Device
Estimated Enrollment
0
Start Date
August 2014
Completion Date
August 2018
Primary Completion Date
August 2018
Eligibility Criteria
Inclusion Criteria:
1. Evidence of VT (shock/ anti tachycardia pacing/ detection) on ICD (single, dual or
bi-ventricular) interrogation or 12 lead ECG.
2. Presumed scar related VT post myocardial infraction infarct/ dilated cardiomyopathy.
3. Age range 18-85yrs.
4. ICD implantation for primary or secondary prophylaxis, or device implantation
pre-discharge from hospital post ablation procedure.
5. Signed informed consent
Exclusion Criteria:
1. Contraindication to catheter ablation
2. Coronary revascularisation required
3. Ventricular tachycardia due to transient, reversible causes
4. Presence of cardiac thrombus
5. Severe cerebrovascular disease
6. Active gastrointestinal disease
7. Renal failure with creatinine >200 μmol/L or on dialysis
8. Active fever or infection
9. Life expectancy shorter than the trial
10. Allergy to contrast
11. Intractable heart failure (NYHA Class IV)
12. Bleeding or clotting disorders or inability to receive heparin
13. Pregnancy
14. Must not have previous (4 weeks prior to screening) or current participation in
another clinical trial with an investigational drug or investigational device
15. Unable to give informed consent
16. Unable to attend follow-up visits or ICD clinics
Gender
All
Ages
18 Years - 85 Years
Accepts Healthy Volunteers
No
Contacts
Prapa Kanagaratnam, MBBChir PhD, ,
Location Countries
United Kingdom
Location Countries
United Kingdom
Administrative Informations
NCT ID
NCT02216760
Organization ID
14HH1922
Responsible Party
Sponsor
Study Sponsor
Imperial College London
Study Sponsor
Prapa Kanagaratnam, MBBChir PhD, Principal Investigator, Imperial College Healthcare NHS Trust
Verification Date
May 2019