Can the Parasternal Long Axis Plane Replace the Apical Four-Chamber Plane in Diagnosing Mitral Valve Prolapse?

Abstract

Since the mitral anulus is now known to be saddle-shaped, use of the qualitative motion of the mitral valve (MV) leaflets in the apical four- chamber plane to diagnose mitral valve prolapse (MVP) may be un sound, in that superior systolic dis placement of the MV leaflets would occur in normal subjects, as well as in patients with MVP. It has therefore been suggested that the parasternal long axis (PLAX) plane should be used to diagnose MVP. To test the feasibility of this approach, the au thors examined the predictive accu racy of PLAX prolapse and other isolated echocardiographic abnor malities versus a multivariate deci sion tree approach. PLAX prolapse, which was significantly associated with marked (> 0.7 cm) apical four- chamber prolapse, mitral regurgita tion, the presence of a thick mitral valve, and low relative body weight, was 100% specific for MVP but only 44% sensitive. Similarly, marked api cal four-chamber prolapse was 100% specific but only 53% sensitive. Api cal four-chamber prolapse, if gauged only qualitatively as present or ab sent, was 94% sensitive but only 50% specific. By contrast, the decision tree classified all 32 initial patients correctly, and in a second, test set, se lected 6 additional patients; these 6 patients had many of the clinical fea tures of MVP. These observations suggest that: (1) if prolapse is seen in the PLAX plane, the patient does have MVP; on the other hand, lack of prolapse in this plane does not ex clude the diagnosis of MVP and (2) the apical four-chamber plane, used qualitatively, does not reliably distin guish patients with MVP from those without MVP.