Tailor-CRT: Better Application of Cardiac Resynchronization Therapy
Condition: Heart Failure; Left Bundle-Branch Block
MeSH terms: Bundle-Branch Block
Study type: Interventional

Summary: 
      Approximately one third of patients treated with cardiac resynchronization therapy (CRT) do
      not derive any clinical benefit. CRT response can be improved by tailoring LV lead placement
      and programming of atrio-ventricular (AV) and inter-ventricular (VV) stimulation intervals to
      the individual patient. However, the best strategy to optimize lead positioning and device
      programming still remains to be established. Earlier work in our research group suggests that
      the vector cardiogram (VCG) can be used to determine the optimal LV lead position and AV- and
      VV-intervals, and pilot studies showed the feasibility to derive a VCG-like signal (D-VCG)
      from the implanted pacing electrodes. Other studies have suggested that the best position for
      the LV electrode is the region of latest electrical activation. The region of latest
      electrical activation can be identified by measuring the electrical delay on the LV lead
      (LVLED) during implantation. The objective of this study is to investigate whether D-VCG can
      be used to determine the optimal AV- and VV-interval and whether VCG and LVLED can be used to
      determine the optimal LV lead position.
    

Detailed description: 
      Cardiac resynchronization therapy (CRT) is an established treatment for heart failure (HF)
      patients with severe left ventricular (LV) systolic impairment and delayed electrical impulse
      conduction through the ventricles, such as left bundle-branch block (LBBB). Since initial
      approval of the therapy over 10 years ago, there have been hundreds of thousands of implants
      worldwide. In The Netherlands, currently more than 2000 CRT devices are implanted each year.
      In a heart with LBBB, electrical activation of the lateral LV free wall is delayed, which
      leads to dyssynchronous and inefficient LV mechanical contraction and compromised LV pump
      function. The positive impact of CRT on LV pump function is attributed to paced
      pre-excitation of the delayed activated lateral LV wall. CRT is most commonly applied by
      pacing the right ventricle (RV) and LV lateral wall (almost) simultaneously. This corrects
      the abnormal LV electrical activation and resynchronizes LV mechanical contraction, which in
      turn results in improved LV pump function.

      Despite the striking effectiveness of CRT, 30-50% of apparently suitable patients show little
      or no improvement. Previous studies have shown that the response to CRT can be improved by
      tailoring LV lead placement and programming of atrioventricular (AV) and inter-ventricular
      (VV) stimulation intervals to the individual patient. In clinical practice, echocardiographic
      techniques are the most widely employed for CRT optimization. However these techniques are
      subject to large measurement errors and inter- and intra-observer variability. A more
      accurate technique is invasive assessment of acute hemodynamic response to CRT, with the most
      widely used invasive hemodynamic parameter being the maximum rate of LV systolic pressure
      rise (LVdP/dtmax). However, the invasive and time-consuming nature of this approach limits
      its use in clinical practice. Thus, the best strategy to optimize lead positioning and device
      programming still remains to be established.

      Earlier work in our research group suggests that the vectorcardiogram (VCG) can be used to
      determine the optimal LV lead position and AV- and VV-intervals, and pilot studies showed the
      feasibility to derive a VCG-like signal (D-VCG) from the implanted pacing electrodes. Other
      studies have suggested that the best position for the LV electrode is the region of latest
      electrical activation. The region of latest electrical activation can be identified by
      measuring the electrical delay on the LV lead (LVLED) during implantation. Validation of
      these techniques for tailoring LV lead positioning and AV- and VV- stimulation intervals to
      the individual patient, will provide non-invasive and easy methods to optimize CRT
      application and improve response rate.

      The objective of this study is to investigate whether D-VCG can be used to determine the
      optimal AV- and VV-interval and whether VCG and LVLED can be used to determine the optimal LV
      lead position. Validation of these techniques for tailoring LV lead positioning and AV- and
      VV- stimulation intervals to the individual patient, will provide non-invasive and easy
      methods to optimize CRT application and improve response rate.
    

Intervention name(s): Cardiac Resynchronization Therapy
Intervention type(s): Device
Intervention description(s): A CRT device will be implanted while performing extra hemodynamic (LV dP/dtmax) and electrical (LVLED, VCG, and D-VCG) measurements. Devices and leads from various vendors will be used.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Cardiac Resynchronization Therapy; LV lead position; Device programming; Optimization; Vectorcardiography