The centerpiece in understanding mitral valve prolapse (MVP) is its definition. Prolapse defined by Webster's dictionary is "the slipping out of place". Thus, slippage of the contact zones of the leaflets constitutes prolapse whether part of the leaflet(s) balloons or not superiorly beyond the annulus into left atrium. Fortunately, two-dimensional echocardiography with doppler and color flow mapping defines the normal and abnormal mitral valve complex for clinical use.
Our study consists of three population groups from a heart institute in a private general hospital (Group I n=11,830), a tertiary state hospital for heart disease (Group II n=9388) and private cardiological practice (Group III n=2920). MVP was diagnosed by echocardiographic criterion of Nagata et al. and doppler color flow mapping for mitral regurgitation (MR). The incidence of MVP in Groups I (n=771), II (n=577) and III (N=63) was 6.5%, 6.1% and 2.1%, respectively. The difference of Groups I and II from Group III is statistically significant (p=<0.001) while Framingham's incidence of 5% is essentially the same as the overall incidence of the three groups (5.8%).
The natural course of MVP with or without trivial MR is generally benign. Mild, moderate or sever MR was noted in 209/771 (27%) in Group I, 357577 (62%) in Group II and 24/63 (38%) in Group III. Ruptured chordae was observed in 8/771 (1.0%) in Group I, 8/577 (1.4%) in Group II and 8/63 in Group III. Endocarditis was present in 2/771 (0.25%) in Group I, 8/577 (1.4%) in Group II and 1/63 (1.5%) in Group III. Prosthetic mitral replacement was done in 9 (1.2%) in Group I, 9 (1.5%) in Group II AND 6 (9.5%) in Group III. Only Groups I and III had 24-hour holter monitoring with arrhythmias in 105/771 (14%) in Group I and 45/63 (71%) in Group III.
Asymptomatic patients without MR are reassured and followed at longer intervals than those with MR. Prophylaxis for endocarditis is recommended for all patients with MR and anticongestive therapy for those with moderate to severe MR. Where appropriate antiarrhythmic agents are used, mitral valve repair or replacement is recommended for severe MR.