CRT Selection Study, A single-center, prospective study to assess response in
patients treated with cardiac resynchronization therapy

Background of the study:
Today it is relatively well accepted that cardiac resynchronization therapy
improves hemodynamic parameters, exercise
capacity, symptoms, and quality of life and also reduces hospitalization among
patients with severe heart failure, impaired
LV function and widened QRS complex usually with a left bundle branch block.
Devices that combine biventricular pacing
with an implantable defibrillator have moreover demonstrated a significant
reduction in arrhythmic death in high-risk
population.
The responsible mechanisms are believed to include improved synchrony of the
timing of left and right ventricular (RV)
systole (interventricular synchrony), improved synchrony of the different
segments of the left ventricle (intraventricular
synchrony), and a reduction in mitral regurgitation.
However, it was noted that 25% to 30% of patients did not respond to CRT,
emphasizing the need for better selection
criteria. In this frame, the resynchronization of pre-existent LV dyssynchrony
is considered a major player in determining
the response to CRT [Yu, Bax]. Indeed detailed echocardiographic assessment
using tissue Doppler echocardiography
showed that patients with left bundle-branch block (LBBB) have marked
intraventricular dyssynchrony that can be
improved by biventricular pacing. [Yu Circ 2002].
Another potential reason for non-response to CRT (in patients with ischemic
cardiomyopathy) may be the presence of
extensive scar tissue in the region of the tip of the LV pacing lead [Bleeker
et all Circ 2007]

The main objective of this study is:
• To determine the optimal site to position the left ventricular pacing lead
for each individual patient with an ischemic
Cardiomyopathy (CMP). The site is selected based on the latest mechanical
activated site and the latest electrical activated
site, whatever pacing configuration tested.
• To assess changes in activation pattern and the hemodynamic effects due to
(single- or dual-site) left ventricular and
biventricular pacing.

This clinical trial is a monocenter, prospective, feasibility, non-randomized
pilot study.
All patients taking part in this study will undergo the implantation of a CRT-D
device with transvenous leads. After
successful implantation and after hospital discharge, patient will be followed
for 6 months after implant. The invasive part
of the study contents two phases where in phase I PV-loop measurements are
performed. In
phase II the device will be implanted at the pre-defined optimal lead
position(s) and pacing configuration.
Patients will attend protocol scheduled visits before implant (pre-implant
evaluation), and post-implant: pre-hospital
discharge and at 6 months.

There is a mild extra risk in concordance to the regular diangnostics in
patient with inschemic heartfailure, as MRI,
echocardiography and electrophysiologic evaluation. During the first invasive
fase Pressure-volume loops are measurend
using a conductance catheter in the left ventricle. The risk of left
ventricular catherization is similar to regular evaluation of
coronary arteriography in patients with coronary artery disease.