Microfidelity (MIFI) Ablation Technology Versus Standard Ablation Catheter for Atrioventricular Nodal Ablation
Condition: Atrial Fibrillation
MeSH terms: Atrial Fibrillation
Study type: Interventional

Summary: 
      The aim of our study is to investigate the comparative efficacy of high fidelity multi
      electrode ablation catheters vs the standard bipolar configuration in success of AV nodal
      ablation This study will provide insights on the use of new technology where application may
      increase efficacy, promote patient and physician safety and decrease costs.
    

Detailed description: 
      Introduction In some elderly patients with atrial fibrillation (AF), especially in
      combination with heart failure, a rate control strategy may be preferred. When
      pharmacological therapy is ineffective or not tolerated, it is reasonable to perform
      atrioventricular (AV) node ablation with ventricular pacing as a class IIA indication per
      current guidelines.

      Usually, the procedure is simple and straightforward and complete heart block can be achieved
      without any difficulty. However, this "simple" procedure can sometimes prove to be a most
      difficult case. The most common reason for failure to achieve complete heart block is the
      inability to localize the compact AV node using the His signal with standard intracardiac
      electrograms. As these patients come to the laboratory in AF, the His signal may be obscured
      by AF waves. In some patients with a deeper intramyocardial location of the His bundle and
      compact AV node it becomes necessary to produce deeper ablation lesions using an irrigated
      catheter to achieve block.

      In patients with AF, the target of ablation for the "ablate and pace" approach is the compact
      AV node, located at the apex of the triangle of Koch. Ideally, ablation is performed at the
      most proximal penetrating part of the His bundle in order to maintain a proximal automatic
      junctional rhythm and avoid pacemaker dependence.

      Para Hisian pacing is most commonly used to reveal the presence of a septal accessory
      pathway.

      The His bundle is a deep insulated structure and it is difficult to capture it at usual
      energy outputs. Using a high- output pacing (usually 20 mA at 2 msec) it is possible to
      directly capture the deeply situated His bundle, which is confirmed by a narrower QRS complex
      on the paced electrograms. Thus, high-output pacing can be utilized to map the His bundle
      area in difficult situations.

      By applying this electrophysiologic principle of differential tissue capture to help identify
      the location of the compact AV node, which is in close proximity to the His bundle.
      Ventricular pacing was performed initially at high output to capture both the basal right
      ventricular myocardium and the His bundle and the output was gradually lowered to lose His
      bundle capture. The QRS duration is relatively narrow with high output pacing and increases
      when the pacing output is lowered, representing ventricular myocardial capture alone.
      Finally, loss of ventricular capture is seen with further reduction of pacing output. This
      maneuver has been shown to aid in determining the proximity of the ablation catheter to
      compact AV node as was validated by successful ablation at this site. Parahisian pacing in
      conjunction with av nodal ablation has recently been described in the literature.

      A novel catheter with three mini electrodes within the ablation tip (IntellaTip MiFi, Boston
      Scientific, Boston, MA) may enhance the available data for such a signal dependent technique.
      In this catheter, bipolar signals can be recorded between the three 0.8-mm-wide electrodes
      that are arranged radially 1.3 mm from the end of the catheter alongside the standard distal
      and proximal bipolar recordings. Animal studies have already demonstrated that the mini
      electrodes in this novel catheter are more accurate in identifying conducting gaps in linear
      ablations than conventional electrode recordings.

      Study Aims:

      The aim of our study is to investigate the comparative efficacy of high fidelity multi
      electrode ablation catheters vs the standard bipolar configuration in success of AV nodal
      ablation This study will provide insights on the use of new technology where application may
      increase efficacy, promote patient and physician safety and decrease costs.

      Primary and secondary objectives Primary endpoints

        1. Acute success of ablation identified by a junctional rhythm or complete heart block

        2. Time from application of radiofrequency energy to acute success

      Secondary endpoints include

        1. Procedure time

        2. Radiation time

        3. Frequency of ablation application

        4. Duration of ablation application
    

Intervention name(s): MIFI Catheter; Standard Ablation Catheter
Intervention type(s): Device; Device
Intervention description(s): Multielectrode Catheter: standard ablation catheter that has the ability to record low and high frequency signals with high fidelity; Standard of care for patients with certain cardiac arrhythmias.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Standard ablation catheter vs MIFI catheter
Masking: Single (Investigator)
Primary purpose: Treatment
Keywords: ablation; atrioventricular node; microfidelity