This longitudinal cohort study evaluates the relationship of myocardial tissue markers characteristics assessed by cardiac MRI, with clinical measures of symptoms and functions in adults with primary mitral regurgitation. Participants are followed conservatively or may choose to undergo surgical repair at the discretion of their clinical team.

The transition from compensated to decompensated chronic primary mitral regurgitation remains poorly understood in the clinical setting. Changes at the myocardial tissue level, such as scar formation and decreased contractility, have been implicated in the end stage, decompensated phase of this disease entity.

Advances in cardiac MRI (CMR) have enabled non-invasive characterization of the myocardial tissue components, such as cardiomyocyte volume and extracellular matrix, and tissue contractility. These measures have been well validated in various cardiac pathologies with biopsy studies but only at single time points.

In this study, adults with isolated chronic primary regurgitation will be followed conservatively over at least a year to determine the natural progression of these CMR-derived markers over time and to investigate the prognostic potential of these markers for clinically assessed functional capacity and symptoms. These participants may elect to undergo any valvular intervention at the discretion of their treating clinical team.

Alongside this arm, similar adults with isolated chronic primary regurgitation will be recruited, who have elected upfront to undergo surgical repair. These patients will be similarly studied to determine reverse remodeling of these CMR-derived markers over time and to investigate the prognostic potential of these markers for the same clinical outcomes.

Inclusion Criteria:

1. Age ≥18 years

2. Isolated mitral regurgitation

   1. of any primary mechanism and
   2. of moderate-to-severe (Sellers 3+) or greater severity, assessed by any imaging modality (echocardiography, angiography, cardiac MRI)

3. Able to receive gadolinium-based contrast agent (estimated glomerular filtration rate >30 mL/min/1.73 m2, no prior allergy to gadolinium contrast agents)

Exclusion Criteria:

1. Refusal to consent
2. Pregnancy during the study
3. Hemodynamically or clinically unstable
4. Inability to undergo a CMR scan, which can include the following reasons: severe claustrophobia, ferromagnetic implants, implanted defibrillator, pacemaker, or abandoned pacemaker leads, cochlear implants, unable to lie flat
5. Other diseases known to influence myocardial fibrosis development (coronary artery disease, diabetes mellitus, uncontrolled hypertension, infiltrative cardiomyopathy, myocarditis, hypertrophic cardiomyopathy, any cardiac tumors, moderate or more valvular heart disease other than primary mitral valve regurgitation)

cardiac MRI referral base, valve specialty clinic