The mitral valve is located between the upper left heart chamber (left atrium) and the bottom left chamber (left ventricle). The Mitral valve opens in the diastole when the left ventricle - which is the main pumping chamber - relaxes and closes in systole when the left ventricle contracts and pumps blood via the aorta into the rest of the body. The mitral valve therefore allows the blood flow only in the correct direction and prevents backflow to the left atrium. Mitral valve prolapse (MVP) occurs when one part of the mitral valve slips into the left atrium during systole. Mitral valve prolapse is often diagnosed in asymptomatic patients on echo following an incidental finding of a murmur during a routine medical examination.

Is mitral valve prolapse dangerous? Some older textbooks and patient blogs on the internet paint a grave picture of debilitating consequences of MVP, including intractable palpitations, dangerous heart rhythm disturbances, infective endocarditis (infection of the heart valves), chest pain and even sudden death.

The truth, however, is that most people with a 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 labelled 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 do 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 blood leaking back to the left atrium, i.e. 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 significant mitral regurgitation may need surgical intervention in the form of mitral valve repair or replacement.