A Comparison of Two Techniques for Choosing the Best Place to Put a Pacing Lead for Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) using biventricular pacing (BiVP) is established as an effective treatment for heart failure. Unfortunately up to 45% of patients do not respond, with no improvement in symptoms or cardiac size. Reducing the proportion of non-responders has become the key research focus in CRT.

Targeting the position of the left ventricular (LV) pacing lead within the coronary vein network has previously been shown to increase the proportion of responders to CRT. Several techniques have been tried for targeting lead position, of which the best investigated are the use of speckle-tracking echocardiography to target the lead position to the site of latest mechanical activation of the left ventricle, and the use of invasive monitoring to select the pacing site at which the greatest acute haemodynamic response (AHR) to BiVP occurs. Both techniques are limited by groups of patients in whom the techniques are not possible or provide limited useful information.

The relationship between these two measures is unknown - there are no previous studies that have investigated correlation between the site of latest mechanical activation determined by echo and the site of maximal AHR. It is likely that a hybrid technique using both of these investigations might allow optimal lead positioning in more patients, or that if the information is shown to be equivalent, more streamlined techniques can be designed.

This study will also be able to contribute towards several important secondary questions. In particular the investigators will study the possibility of using non-invasive cardiac output monitoring (NICOM) to assess haemodynamic response rather than an intravascular pressure monitor wire. The investigators also wish to assess whether the site of latest mechanical activation is changed by right ventricular pacing.