An old controversy solved by echo
The mitral valve separates the upper left heart chamber (left atrium) and the lower left chamber (left ventricle). Mitral valve allows only blood flow from the left atrium to the left ventricle, and prevents the blood from flowing in the opposite direction. Mitral valve prolapse (MVP) occurs when one part of the mitral valve slips into the left atrium during the heart muscle contraction (systole). It is often an incidental finding during a routine medical examination, as it produces a characteristic murmur.
Is mitral valve prolapse dangerous? Some old textbooks and patient blogs on internet paint a grave picture of debilitating consequences of MVP including intractable palpitations, dangerous heart rhythm problems, infective endocarditis (infection of the heart valves), chest pain and even sudden death.
The truth however is that most people with mild form of mitral valve prolapse are not even aware of its existence and will never have any symptoms or complications. The confusion stems from the pioneer era of echocardiography (heart ultrasound) with massive overdiagnosis of MVP on background of limited diagnostic accuracy and no reliable diagnostic criteria. People who have been labeled with the condition a long time ago may now be reluctant to accept that their symptoms are due to anxiety and stress and have nothing to due with any serious heart problem.
The significance of mitral valve prolapse lies in its impact on the correct function of the mitral valve. In some patients, the prolapsed mitral valve leads to leaking of blood back to the left atrium, a condition called mitral regurgitation. As the disease progresses, the volume of blood flowing in the wrong direction gradually increases, and over time, the heart becomes enlarged and weak, i.e. heart failure develops. People with a significant mitral regurgitation may need a surgical intervention in the form of mitral valve repair or replacement.