[Systolic clicks in mitral valve prolapse: their pathophysiological relationship to the grade and causes of prolapse].

To re-evaluate the clinical significance of non-ejection systolic clicks in mitral valve prolapse (MVP), 154 patients with idiopathic MVP (idiopathic group) and 54 patients with secondary MVP associated with atrial septal defect (secondary group) were studied using phonocardiography and two-dimensional echocardiography. There was no significant difference in the incidence of systolic clicks between the idiopathic (30%) and secondary (24%) groups. The severer the degree of prolapse, the higher the incidence of systolic clicks in both the groups. A systolic click was observed independently of age in the idiopathic group. In the secondary group, however, a systolic click was not observed in patients under 30 years old and increased with advancing age in frequency. The intensity of systolic click tended to increase in proportion to the increase of severity of prolapse in both the groups. These results suggested that systolic clicks may appear irrespective of the causes of prolapse and that the production and the intensity of systolic clicks may be related to the degree of changes in the mitral valve-chordal system and the degree of prolapse.