The role of left atrial fibrosis in mitral valve repair surgery

Patients with mitral valve insufficiency (MVI) frequently suffer from left
atrial (LA) remodeling, caused by volume overload and subsequent atrial
dilatation.

The associated myocardial stretch and increased wall tension, trigger a cascade
of pathways leading to the occurrence of atrial fibrosis as part of the
remodeling process. The clinical relevance of this atrial fibrosis, is that its
presence is associated with an increased risk of atrial fibrillation (AF),
heart failure (HF), pulmonary hypertension (PH), a reduced quality of life and
eventually a shorter life expectancy. In addition, in patients suffering from
atrial fibrillation (AF), the presence and amount of LA fibrosis was found to
be a strong predictor for ablation efficacy and long-term outcome.

In daily clinical practice, MVI is managed either by medical or surgical
therapy. However, since medical therapy is often not sufficient for patients
with severe primary MVI, surgical intervention remains the ultimate treatment
option for these patients. In general, valve repair is the preferred type of
surgery, since it has better clinical results compared to valve replacement.
Currently, the indication and timing for valve surgery is mainly based on the
severity of MVI and the presence of symptoms and/or severity of left
ventricular dysfunction.

For clinical decision making and patient stratification for mitral valve
surgery, the presence of atrial fibrosis is currently not taken in account,
despite its well-recognized clinical implications.

Detection of atrial fibrosis patterns in patients with severe MVI, however, may
be potentially valuable for the indication and timing of mitral valve repair
surgery to improve clinical outcomes. Improved insight into atrial fibrosis
patterns and changes after mitral valve repair due to reverse remodeling, may
help clinicians in their decision and timing for surgery.

Today, quantification of atrial fibrosis can be routinely performed using
cardiac magnetic resonance imaging (CMR) techniques and advanced
post-processing techniques, offering non-invasive tissue characterization in
the thin-walled structures.

Unfortunately, MVI patients suffering from LA remodeling have hardly been
studied using these new imaging techniques. Therefore, in this study, we want
to combine advanced cardiac MRI and post-processing techniques prior to and
after mitral valve repair surgery to gain insight on the clinical role and
meaning of atrial fibrosis in this patient population.

In addition, we aim to assess the effects of (reduced) volume overload on
atrial wall texture, geometry and function.

It is hypothesized that the atrial fibrosis surface area paradoxically will
increase after mitral valve surgery because of global shrinkage of the LA
caused by the reversed remodeling process. As a consequence, more frequently
atrial fibrosis related events including (paroxysmal) AF, will be observed in
these patients.

With this insight, CMR can become clinical valuable for the indication and
timing of surgical intervention in these patients. Surgical therapy might be
renounced for example when a substantial increase of fibrosis surface is
expected post-surgically causing a higher risk for AF, HF, PH and a reduced
quality of life. On the contrary, surgical therapy might be considered in an
earlier stage of disease when the fibrosis surface is still acceptable
regarding its expected post-surgical development.

To assess the effects of (reduced) volume overload on the left atrial wall
texture (presence, amount and location of atrial fibrosis) and associated
geometry and function in patients with MVI, prior to and after elective mitral
valve repair surgery.

This study is designed as a single center pilot study.

Study subjects that will be included are MVI patients who meet the criteria for
mitral valve repair surgery and are on the waiting list for elective surgery.
Furthermore, the study subjects are not allowed to meet any exclusion criteria
(AF, history of cardiac surgery, comorbidities, MRI contra-indications). These
study subjects will be recruited from the Amsterdam UMC surgical waiting list.

The study subjects will visit the AmsterdamUMC hospital (Location VUmc) two
weeks prior to mitral valve repair surgery for a CMR scan. This visit will
start with checking in- and exclusion criteria using questionnaires regarding
medical history and MRI safety. The total duration of the visit - including the
CMR scan - will be approximately two hours.

Two weeks later the subjects will undergo the indicated mitral valve repair
surgery (Location AMC). During anesthesia, a Swan-Ganz catheter will be used
for hemodynamic monitoring. This is all part of standard care and is not
influenced by our study.

In the follow-up phase, subjects will visit the AmsterdamUMC hospital (Location
VUmc) three months after surgery again for evaluation of the hemodynamic
physiology and tissue development (fibrosis).

This is an MRI study with use of contrast media (Gadolinium). Gadolinium is a
safe contrast agent, which is frequently used in clinical practice. Intravenous
gadolinium administration may cause minimal injection site reactions (e.g.
pain, cold or burning sensation). As with other contrast-agents,
anaphylactic-like reactions can occur. However, due to the design of modern day
contrast agents, allergic-type reactions to gadolinium are very rare and
unusual. Therefore, there is no associated risk expected for participating
patients

There are no direct benefits for individuals participating to our study.