Did a quick literature search on mitral valve regurgitation. Among its symptoms are shortness of breath, fatigue, heart palpitations, and fluid build-up. It's often discovered when a heart murmur is heard, or is seen on an echocardiogram. There are numerous causes, including certain medications, uncontrolled high blood pressure, aging, and various infections including rheumatic fever and myocarditis.
Severe mitral valve regurgitation may require valve surgery, but milder cases often respond to blood pressure medications (including diuretics and ACE inhibitors), a low-sodium diet, weight loss, cutting out alcohol, cigarettes and caffeine, exercising, and generally having a healthy lifestyle.
MVR is most concerning if the patient has other heart conditions such as a previous heart attack or irregular heart rhythm, but many cases require only lifestyle adjustments.
Because rheumatic fever can damage the mitral valve, it's important to promptly treat Streptococcus infections such as Strep throat.
Disclaimer: I am not a doctor, but I do work in the medical field.