[Mitral valve prolapse in idiopathic ventricular tachycardia: clinical and electrophysiologic characteristics]

The frequency and significance of mitral valve prolapse (MVP) were assessed in 35 patients with idiopathic ventricular tachycardia (VT) (12 with sustained VT and 23 with nonsustained VT). They were classified as MVP and non-MVP groups according to their results of two-dimensional echocardiography. The frequency and characteristics of MVP in idiopathic VT, symptoms during VT, QRS configurations on electrocardiogram during VT, and induction of VT in electrophysiologic study were evaluated. MVP was recognized in 12 (34.3%) of 35 patients with idiopathic VT, all of whom had mild prolapse of the anterior leaflet. The frequency of MVP in patients with sustained VT was higher than that in patients with nonsustained VT (58.3% vs 21.7%, p < 0.05). Of all the symptoms during VT, palpitation was most frequently observed in the MVP group (66.7%), while no characteristic symptom was observed in the non-MVP group. This symptomatic difference was considered to be attributable to different patterns of VT duration. QRS configurations during VT showed monomorphism in all patients. The right bundle branch block pattern was dominant in the MVP group (91.7%), while the left bundle branch block pattern was prominent in the non-MVP group (69.6%) (p < 0.01), suggesting that VT mainly originated in the left ventricle in the MVP group and in the right ventricle in the non-MVP group. The induction rate of VT by programmed ventricular stimulation was higher in the MVP group (58.3%) than in the non-MVP group (34.8%) (p < 0.07) and was considerably higher in patients with sustained VT (75.0%) than in patients with nonsustained VT (26.1%) (p < 0.01). However, there was no significant difference in the induction rates between patients with sustained VT in the MVP and non-MVP groups. The difference in the VT induction rates between the 2 groups may be related to other factors besides the duration of VT. In conclusion, the incidence of MVP was relatively high in patients with idiopathic VT, and the difference of the clinical and electrophysiologic characteristics of idiopathic VT may depend on whether MVP is present or not.