Rarel. Mitral valve prolapse can cause palpitations, shortness of breath, or chest pain but isi seldom fatal. If the valve is leaking severely or if it gets infected, the problem can become serious.
No. Mitral valve prolapse is really a description of how the leaflets come together. Normally the leaflets meet slightly below the valve but in prolapse the leaflets bow up into the left atrium. Valves can function normally even with prolapse. In some people the prolapse can cause the valve to leak. But prolapse by itself is not fatal.