[Diagnosis of idiopathic mitral valve prolapse by two-dimensional echocardiography: evaluation of its clinical significance in the prospective follow-up study].

One hundred and five cases with idiopathic mitral valve prolapse (MVP) diagnosed by two-dimensional (2-D) echocardiography were classified into 5 groups according to the grade of prolapse (Fig. 1), 47 cases of which were followed prospectively for average 2.9 years. 1) Most of the cases with MVP of grade 3 or less showed normal left ventricular diastolic dimension (LVDd) and left atrial dimension (LAD) throughout the follow-up period, while the majority of the cases with MVP of grade 4 revealed increased LVDd and LAD. Thus the mitral regurgitation due to MVP seemed to be insignificant in cases of grade 3 or less, while it is significant in cases of grade 4. 2) During the follow-up period cases of grade 1, 2 and 3 showed the transition of the grade of prolapse each other. On the other hand, most of the cases of grade 4 at the initial examination did not show the change in its grade of prolapse. 3) Fifty-eight cases (55.2%) had symptoms such as chest pain, palpitation and dizziness, and various electrocardiographic abnormalities such as ST and T wave changes, prolongation of QT interval and arrhythmias were also frequently observed. However, the incidence of these symptoms and signs was independent from the grade of MVP. It was concluded that MVP with grade 4 or more is hemodynamically significant, while it was insignificant in cases of grade 3 or less. Therefore, those with symptoms and/or electrocardiographic abnormalities in cases with MVP of grade 3 or less will not require any treatment but only a follow-up observation.