The mitral valve is the inflow valve into the main pumping chamber of the heart. It can become leaky or narrow, and cause blood to back up into the blood vessels of the lungs. When patients get symptoms from a leaky or narrow mitral valve, surgery is recommended to either fix or replace the valve. Many patients with mitral valve disease also develop a leaky tricuspid valve - the tricuspid valve is the inflow valve to the right side of the heart (the right heart pumps blood across the lungs). The amount of leakiness of the tricuspid valve is determined by an ultrasound test, and the amount of leakiness is graded as: none, mild, moderate, or severe. When a heart surgeon operates on a patient with a diseased mitral valve, he or she will fix the tricuspid valve if the tricuspid leakage is severe. This involves sewing a cloth-covered ring around the valve and narrowing it. If the tricuspid valve leakage is only mild (or absent), the surgeon will leave the tricuspid valve alone at the time of mitral valve surgery. If the tricuspid valve has moderate leakage surgeons are uncertain about what to do. In a recent review of thousands of patients across the nation having mitral valve surgery with moderately leaky tricuspid valves, 35 % of patients had tricuspid valve repair. Since the investigators don't know what the best approach is: to leave the moderately leaky tricuspid valve alone or to fix it with a cloth-covered ring, the investigators propose a study to determine which approach is best. Patients having mitral valve surgery with a moderately leaky tricuspid valve will be randomized to either 1. have a tricuspid valve repair or 2. to not have a tricuspid valve repair. The investigators will carefully follow these patients for two years and see if heart function is better among those who got their valve fixed.

Study Design:

This is a single-center prospective, randomized controlled clinical trial.

Enroll/Randomize: mitral operation alone, or mitral operation with tricuspid valve repair. Randomization will occur before operation.

Operation: The surgeon will perform mitral surgery and only those patients randomized to tricuspid valve repair will perform tricuspid valve repair using a rigid 3-dimensional annuloplasty ring using standard techniques.

Inclusion Criteria:

1. All patients 18-65 + older years undergoing mitral valve surgery.
2. Presence of moderate or mild-moderate tricuspid regurgitation as read on any echocardiographic study performed within 6 months prior to operation. Assessment if tricuspid regurgitation will be performed using an integrative method.
3. All patients referred for mitral valve surgery.
4. Able to understand the consent and able to sign informal consent.

Exclusion Criteria:

1. Patients under 18 years of age.
2. Patient with structural/ organic tricuspid valve disease.
3. Refusal/ Inability to sign informal consent form.
4. Pregnant women.
5. Tricuspid valve endocarditis.
6. Requirement for concomitant cardiac surgery (other than atrial fibrillation correction surgery, closure of PFO (Patent Foramen Ovale) or ASD (Atrial Septal Defect), or coronary artery bypass surgery).
7. Cardiogenic shock at the time of randomization.
8. ST segment elevation myocardial infarction requiring Intervention within 7 days prior to randomization.
9. Evidence of cirrhosis or hepatic synthetic failure.