Guideline‑Recommended Evaluation and Management of Mitral Regurgitation

Primary Causes of Mitral Regurgitation

Degenerative mitral valve disease—including myxomatous degeneration, fibroelastic deficiency, and Barlow’s disease—is a leading primary cause of mitral regurgitation (European Society of Cardiology) 3.
Infective endocarditis can produce primary mitral valve dysfunction (American Society of Clinical Oncology) 4.
Ischemic papillary‑muscle rupture or dysfunction may result in primary mitral regurgitation (European Society of Cardiology) 3.
Prior thoracic radiation therapy is an established cause of radiation‑induced valvular disease affecting the mitral (and aortic) valve (American Society of Clinical Oncology) 4.

Ischemic cardiomyopathy leading to left‑ventricular remodeling and papillary‑muscle displacement produces secondary mitral regurgitation (American College of Cardiology) 5.
Dilated cardiomyopathy causing annular dilation is a common mechanism of functional mitral regurgitation (European Society of Cardiology) 2.
Any left‑ventricular dysfunction that tethers mitral leaflets can generate secondary mitral regurgitation (European Society of Cardiology) 2.

Echocardiography should be used to determine whether mitral regurgitation is primary (structural valve abnormality) or secondary (functional due to ventricular remodeling) (European Society of Cardiology) 2, 3.
Carpentier’s classification is recommended for characterizing leaflet motion:
- Type I – normal motion,
- Type II – excessive motion/prolapse,
- Type III – restrictive motion (European Society of Cardiology) 3.

Severe primary mitral regurgitation: Surgical intervention is indicated when the patient is symptomatic (NYHA class II–IV) or when asymptomatic with left‑ventricular ejection fraction ≤ 60 % or left‑ventricular end‑systolic dimension ≥ 40 mm (European Society of Cardiology; American College of Cardiology) 2, 5.
Severe secondary mitral regurgitation: Optimize guideline‑directed heart‑failure medical therapy first; surgery is reasonable when the patient undergoes concomitant coronary‑artery bypass grafting and has left‑ventricular ejection fraction > 30 % (European Society of Cardiology; American College of Cardiology) 2, 5.
Mitral‑valve repair is preferred over replacement whenever feasible for primary mitral regurgitation (American College of Cardiology) 5.

Do not attribute mitral regurgitation to Agent Orange exposure without first excluding well‑established etiologies such as degenerative disease, ischemic mechanisms, rheumatic disease, and endocarditis (European Society of Cardiology) 1, 2, 3.
Do not delay indicated surgical treatment while searching for an uncertain exposure‑related cause; timing should follow guideline‑based severity, symptom, and ventricular‑function criteria (European Society of Cardiology; American College of Cardiology) 2, 5.
Recognize that prior chest radiation is a recognized cause of both mitral and aortic valve disease and should be considered in the differential (American Society of Clinical Oncology) 4.
Be aware that ischemic heart disease—already linked to Agent Orange exposure—can produce secondary mitral regurgitation via papillary‑muscle dysfunction or ventricular remodeling (American College of Cardiology) 5.