Efficacy, Safety and Efficiency of the nMARQ Pulmonary Vein Isolation System in Paroxysmal Atrial Fibrillation
Condition: Paroxysmal Atrial Fibrillation
MeSH terms: Atrial Fibrillation
Study type: Interventional

Summary: 
      This is a pilot study designed to investigate the effectiveness of the nMARQ Pulmonary Vein
      Isolation system in the treatment of Paroxysmal Atrial Fibrillation (AF) at different
      ablation settings.

      AF is a common condition which causes a fast and erratic heartbeat. There are estimated to be
      50,000 new cases diagnosed per year in the UK. The fast heart beat can cause symptoms such as
      palpitations, lightheadedness, chest pains, shortness of breath and fatigue.

      Catheter ablation is a technique used for the control of AF. In this procedure a catheter (a
      long thin wire) is passed into the chambers of the heart via a large blood vessel in a leg.
      The tip of the catheter can destroy tiny sections of heart tissue that may be the source or
      trigger of the abnormal electrical impulses. One of the challenges of AF ablation is to
      maximize success rates, as such there is currently rapid advances in technology to carry out
      this procedure.

      Different catheters exist which deliver this energy in different ways. This study uses one
      such system to perform this procedure. It is called the nMARQ system for Pulmonary Vein
      Isolation produced by Biosense Webster. Currently this system is used in practice in the UK
      for patients with this medical condition.

      What we seek to research is when ablating what is the optimum setting to perform ablation at.
      There is currently no data to guide best clinical practice in this area.
    

Detailed description: 
      This is a pilot study designed to investigate the use of the nMARQ Pulmonary Vein Isolation
      system in the treatment of Paroxysmal Atrial Fibrillation (AF) at different ablation
      settings.

      At least one month prior to the ablation procedure, an Implanted Loop Recorder (ILR) (the
      REVEAL XT) will be implanted into the patient for robust, continuous, long term monitoring of
      the burden of arrhythmia following the case.

      It has been decided to use continuous implanted rhythm monitors to allow for robust complete
      data capture of arrhythmia recurrence and burden with little impact to the patient after
      implantation. These are increasingly being used in the follow up of patients undergoing AF
      ablation. They give a continuous data feed showing the presence and quantity of abnormal
      rhythm seen after ablation. Their use has been approved in the follow up of AF ablation
      procedures within recent consensus guidelines formulated by the American College of
      Cardiology, the American Heart Association, the European Cardiac Arrhythmia Society, the
      European Heart Rhythm Association, the Society of Thoracic Surgeons, and the Heart Rhythm
      Society. There are several papers showing the validation of data collected by the REVEAL XT
      ILR and the benefit of continuous monitoring versus conventional methods of intermittent
      ambulatory ECGs.

      The settings chosen for ablation are guided both by preclinical data collected by Biosense
      Webster and also the settings being used clinically worldwide when utilising this system. It
      has been decided to have a two by two study design varying the wattages 20W and 25W and also
      varying the time periods per lesion 20 seconds and 40 seconds.

      We feel that this project can be carried out as a pilot study to potentially inform further
      research. There is very little clinical data published on how best to use of this device. At
      present it is left to individual clinicians to form their own "best practise" when choosing
      ablation settings. We seek to formalise the potential ablation variables into a structured
      format that will allow for comparisons to be drawn at the end of the study and to form the
      basis of future research.

      Following the current pathway, patients are admitted 24 hours prior to their treatment for
      further, standard, tests (including an Echo TOE and pregnancy test); at this point patients
      will be randomised to one of the arms of the trial, at an equal 1:1:1:1 ratio. As the study
      is ' unblinded ' and the procedure constitute standard care in the NHS , it would be at this
      point that the participant and Consultant have time to discuss the impact of the setting that
      the participant has been randomised to, thereby reducing any anxiety on the day of the
      procedure.

      The following day, the procedure would be carried according to standard treatment and
      following national guidelines using one of the ablation presets as per randomisation.

      Within the UK it is standard practice to have a follow-up visit at 6 weeks, 3 months, 6
      months and 12 months. At each visit, in addition to the standard tests, the patient and
      Consultant would complete questionnaires.

      After one year the patient will attend for removal of the ILR unless it is deemed to have
      clinical use for them.

      Recruitment and Consent Our target population will be patients who would routinely be having
      catheter ablation of their AF. They will have the kind of AF that comes and goes and will be
      troubled symptomatically by it. This research study has been constructed around a patients'
      normal care pathway, minimising the need for additional visits or activities.

      Risks, burdens and benefits Potential risks and burden of participation in the study centre
      on the use of the ILR for rhythm recording both before and after the ablation procedure. This
      device is small and implantation is a minor day case procedure done under local anaesthetic.
      The risk of implantation is very small. Its use in the follow up after AF ablation is
      endorsed by international clinical guidelines and backed up by scientific data. The use of
      the ILR after AF ablation is becoming more commonplace and if anything is constrained by
      financial issues in the NHS rather than any ethical considerations about the risks or burdens
      of implantation.

      Potential benefit to the participant also involves the ILR. By having a continuous monitor of
      heart rhythm after ablation the consultant has information that can guide clinical management
      decision making after the ablation occurs. In clinical practise, without the ILR in place,
      the patient would otherwise have to undergo a number of ambulatory ECG monitors periodically
      throughout the follow up period
    

Intervention name(s): ablation
Intervention type(s): Procedure
Intervention description(s): Ablation ranging from 20-25 watts / 30-45 seconds
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: pilot study; atrial fibrillation; ablation; implanted loop recorder