Improving Mitral Repair for Functional Mitral Regurgitation

The investigators are interested in determining the best surgical technique to correct functional mitral regurgitation, as there is currently not one technique that is established to work better than the other.

The technique used in current clinical practice is undersizing mitral annuloplasty (UMA), in which a prosthetic ring is implanted onto the mitral valve to correct the leakage. Though widely adopted, durability of the repair is less, as 58% of the patients present with recurrent FMR within 2 years. There are no specific algorithms to predict who might have UMA failure, but research indicates that some geometric indices might be strong predictors. The investigators are interested in testing the hypothesis that, elevated lateral inter-papillary muscle separation (IPMS) is a predictor of post-UMA recurrence of FMR at 12 months. In the first part of this study, the study team will measure lateral IPMS before surgery and relate to post-surgery FMR severity at discharge/30 days, 6 months and 12 months.

A relatively newer 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. This reduces the lateral inter-papillary muscle separation (IPMS) and is expected to improve the durability of UMA. In the second part of this study, the investigators will perform PMA and UMA together and determine if FMR severity is reduced at discharge/30 days, 6 months and 12 months.

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.

Eligibility Criteria:
Inclusion Criteria:

* Mitral regurgitation of moderate or greater severity, as defined by the guidelines of the American Society of Echocardiography (via a transthoracic echo)
* Cardiomyopathy of ischemic or non-ischemic origins, with or without the need for coronary revascularization
* Concomitant right-sided valve repair or replacement (i.e. patients requiring concomitant tricuspid procedures)
* Able to sign informed consent and release of medical information forms

Exclusion Criteria:

* Any evidence of structural (chordal or leaflet) mitral lesions
* 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 before inclusion in this study
* Congenital heart disease, except patent foramen ovale (PFO) or atrial septal defect (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