Improving Mitral Repair for Functional Mitral Regurgitation

Functional mitral regurgitation (FMR) is a common heart valve lesion that is observed in
patients suffering for cardiomyopathies. Timely surgical repair of FMR can reduce volume
overload and potentially improve cardiac function. Durable surgical techniques for FMR repair
are lacking. Undersizing mitral annuloplasty (UMA) is the current technique of choice, but
its durability is quite poor. Thirty five percent of the repairs fail within one year and 58%
fail within 2 years.

One of the probable mechanisms causing UMA failure is elevated lateral inter-papillary muscle
separation (IPMS). The study investigators are interested in understanding if the extent of
lateral IPMS has a direct impact on the failure rates of UMA at 1 year post surgery.
Secondly, the investigators are interested in determining if patients with elevated lateral
IPMS benefit from papillary muscle approximation (PMA) along with UMA.

The investigators are interested in determining the best way to correct functional mitral
regurgitation, as there is currently not one technique that is established to better than the
other. The most common repair technique is called undersizing mitral annuloplasty (UMA), in
which a prosthetic ring is implanted onto the mitral valve to correct the leakage. Another
more recent technique is papillary muscle approximation (PMA), in which a suture draws
together the two muscles that connect the mitral valve to the heart muscle prior to
performing UMA. In this research study, the study team is investigating whether they can
identify those patients who will benefit from one repair over another.

The primary objective of this protocol is to investigate if pre-operative IPMS is predictive
of FMR severity at 12 months after UMA to repair FMR. Furthermore, whether a cut-off value of
pre-operative inter-papillary muscle separation can be established to predict patients who
might have failure of UMA.

The secondary objective of this protocol is to investigate if adding PMA to UMA is an
effective technique in reducing recurrence of FMR at 12 months post-procedure.

Inclusion Criteria:

Patients with functional mitral regurgitation (FMR) from either ischemic or non-ischemic
cardiomyopathies, referred for surgical or transcatheter mitral valve annuloplasty.
Suitability for mitral annuloplasty is determined by the surgeon, using some or all the
criteria described below:

- Left ventricular end diastolic diameter is less than or equal to 70mm.

- Systolic tenting height is less than or equal to 12mm

- Mitral regurgitation of moderate or greater severity, as defined by the guidelines of
the American society of echocardiography at the time of the study approval (via a
transthoracic echo).

- Cardiomyopathy of ischemic or non-ischemic origins, with or without the need for
coronary revascularization.

- Able to sign informed consent and release of medical information forms, or able to
assign a legal representative who can sign on the patient's behalf.

Exclusion Criteria:

- Any evidence of structural (chordal or leaflet) mitral lesions.

- Planned concomitant intra-operative procedures (except for closure of patent foramen
ovale or atrial septal defect)

- Planned concomitant intra-operative Maze procedure for symptomatic paroxysmal atrial
fibrillation.

- Persistent atrial fibrillation

- Prior mitral valve repair

- Contraindication for cardiopulmonary bypass

- Clinical signs of cardiogenic shock at the time of randomization

- ST segment elevation myocardial infarction within 14 days prior to inclusion in this
study.

- Congenital heart disease (except PFO or ASD)

- Chronic renal insufficiency defined by Creatinine ≥ 3.0 or chronic renal replacement
therapy, who are contraindicated for cardiac surgery

- Recent history of psychiatric disease that is likely to impair compliance with the
study protocol, in the judgement of the investigator

- Pregnancy at the time of randomization