HV Electrophysiology Study In Transcatheter Aortic Valve Implantation Patients

Aortic valve stenosis is the most frequent type of valvular heart disease in
Western countries. Although the recommended treatment for severe and
symptomatic aortic valve stenosis is surgical valve replacement, the operative
risk can be very high in older patients with comorbidities, which impedes the
decision to perform surgery. Transcatheter aortic valve implantation (TAVI) has
proven to be an elegant alternative for patients with high risk for classic
surgical aortic valve replacement.

The TAVI procedure is frequently complicated by the development of a new left
bundle branch block (LBBB) with an incidence varying from 7% to 65%, with an
average of 28.5%, depending on the type and size of prosthesis being used. The
TAVI-induced LBBB, however, is associated with poorer outcome, as there is an
increased risk of developing high-degree atrioventricular conduction disorders
possibly leading to bradyarrhythmia and death.

Until present, new LBBB has been diagnosed from ECG acquired at the
post-procedural department. However, our experience has shown that there is a
group of patients who develop a short term LBBB which has disappeared within 60
minutes, which often is before the first ECG post-procedural.

The common belief has been that the *damage* in a LBBB is located in the left
bundle branch. However, a LBBB can also be located in the His-bundle, the
common bundle preceding the Left and Right Bundle Branch. The left bundle and
the His bundle are both located near the location in the outflow tract of the
left ventricle where the new valve is placed during the TAVI procedure.

If a TAVI-induced LBBB progression to a high-degree atrioventricular conduction
disorder can be predicted, bradyarrhythmic death can be prevented by
implantation of a pacemaker. On the other hand also an unnecessary pacemaker
implantation could be prevented.

Preliminary electrophysiology studies have shown that in patients with new-LBBB
after TAVI, a post-procedural HV interval of * 65ms is predictive of AV block
in the follow-up. These studies, however, are retrospectively analysed from
prospective acquired data, do not look at the anatomical location of the block,
do not take persistency and timing of the new LBBB into consideration and have
a limited follow-up.

Elucidation of the anatomical location of the conduction pathology of a LBBB
could impact valve design and placement and thereby reduce the number of new
LBBB induced by TAVI. Furthermore, finding predictors for progression to a high
degree AV block in the follow-up (and thus an indication for permanent
pacemaker) could improve management of post-operative conduction abnormalities
and prevent the risk of brady-arrhythmic death.

Primary Objective:
1. To investigate the anatomical location of a TAVI-induced LBBB.

Secondary Objectives:
1. To investigate during which phase of the TAVI-procedure the conduction
disorder develops.
2. To investigate predictors for the occurrence of TAVI-induced LBBB.
3. To investigate predictors for the persistency of the TAVI-induced LBBB.
4. Pilot study for the power calculation of a future study to investigate
electrophysiological predictors for progression of new LBBB to a high degree
AV-block in the follow-up period (and thus pacemaker indication).

A prospective, single center, non-randomized pilot study in which patients will
undergo an electrophysiology (EP) study during the TAVI procedure.

Patients need to undergo one extra femoral vein puncture, in addition to the
other standard arterial and venous femoral punctures used with TAVI, to insert
a HIS-catheter, a standard electrophysiological catheter to measure the
HV-duration during the entire procedure. This procedure carries a very low
complication risk limited to local hemorrhage in the groin and will prolong the
operation with only a few minutes. There will be no direct benefits for the
patients participating in the study.