Quantitation and significance of systolic mitral leaflet displacement in mitral valve prolapse.

Superior systolic displacement of the mitral leaflets is the echocardiographic finding generally used to diagnose mitral valve prolapse, but its clinical significance is not clearly established. This study was designed to determine if the presence of leaflet thickening, displacement in the multiple imaging planes or the quantitative degree of displacement could be used to identify clinically important valvular abnormality. To this end, these findings were prospectively assessed and correlated with the presence of mitral regurgitation and ventricular arrhythmia in 49 patients with displacement and in 49 age-matched control subjects with no identifiable displacement. Both ventricular arrhythmia and mitral regurgitation were found to occur with significantly greater frequency in patients with leaflet displacement than in control subjects. However, among the patients with leaflet displacement, both these complications occurred with greater frequency in subgroups characterized by the presence of leaflet thickening, quantitatively greater displacement and displacement evident in 2 orthogonal imaging planes. Logistic regression analysis demonstrated that the best echocardiographic predictor of either ventricular arrhythmia or mitral regurgitation was the quantitative degree of leaflet displacement. These results indicate that most patients with echocardiographic evidence of leaflet displacement had very low incidences of ventricular arrhythmia and mitral regurgitation. Subgroups, however, could be identified echocardiographically in which both complications occurred with significantly greater frequency.