The current American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend surgery in patient with mitral regurgitation (MR) based on 1) the severity of MR and 2) the presence or absence of symptoms. Studies have shown that Cardiovascular Magnetic Resonance (CMR) is an accurate method to quantify the severity of MR. However, studies have also shown that symptoms are not necessarily related to the presence of symptoms. Thus, there appears to be a disconnect between the severity of MR and symptoms. Recent analysis of our data has shown that females and older patients with smaller ventricles, lower stroke volumes, and lower regurgitant volume relative to regurgitant fraction tend to be symptomatic. These findings suggest that decreased left ventricular compliance, i.e. diastolic dysfunction, may play an important role as an etiology of symptoms in patients with mitral regurgitation. The aim of this study is to study the presence of diastolic dysfunction in patients with MR and its association with symptom burden and exercise capacity.

The study is an observational study of patients with mitral regurgitation undergoing LHC prior to mitral valve surgery or percutaneous mitral valve intervention. Prior to patients LHC they will undergo testing using CMR, CPET, and KCCQ. During the LHC, patients will undergo evaluation of intracardiac pressures and volumes using a specialized catheter which measures pressure and volume changes throughout the cardiac cycle.

CMR- CMR evaluation will quantify mitral regurgitant volume and fraction, right and left atrial size and function, and myocardial scar quantification.

CPET- objectively assess patients exercise capacity. KCCQ- is a standard questionnaire designed to assesses patients quality of life and symptom burden.

LHC- Pressure-volume loops will be measured during LHC. This will quantify left ventricular compliance and assess patients for the presence of diastolic dysfunction.

These evaluations will help us better understand the relationship between symptoms, exercise capacity, severity of MR and diastolic dysfunction.

Inclusion Criteria:

• Age >=18 years of age
• Able to give informed consent
• Primary (degenerative) mitral regurgitation
• LVEF >=50%
• Undergoing cardiac catheterization
• Able to exercise on a treadmill

Exclusion Criteria:

• Unable to give informed consent
• Secondary (functional) mitral regurgitation
• LVEF <50%
• Known coronary artery stenosis >=70% or past revascularization
• More than mild aortic stenosis, mitral stenosis, aortic regurgitation, tricuspid regurgitation, or pulmonic regurgitation
• Hypertrophic cardiomyopathy
• Pregnancy

This study if for patients with mitral regurgitation who are undergoing cardiac catheterization prior to mitral valve surgery or mitral valve clip.