Relation between QT dispersion and ventricular arrhythmias in uncomplicated isolated mitral valve prolapse

Complications of mitral valve prolapse (MVP), among which serious ventricul ar arrhythmia and sudden death are of major importance, affect many individ uals due to the high incidence of MVP itself in the community despite the a ctual low incidence of these complications. The present study investigated the incidence and distribution of ventricular arrhythmias according to thei r severity and relationship with the QT interval and dispersion of repolari zation in uncomplicated isolated MVP (IMVP) cases. Fifty-eight uncomplicate d IMVP patients, 33 patients with accompanying tricuspid valve prolapse (TV P), to compare its relationship with ventricular arrhythmia, and 60 age- an d sex-matched control subjects were enrolled in the study. Individuals with accompanying cardiac or systemic disease, or who were on drug therapy that could potentially affect QT characteristics, were excluded. The incidence of ventricular arrhythmia was 48% in the IMVP group and 64% in the TVP grou p; the difference was statistically insignificant. In addition, the differe nces of the QT and Q peak T values were insignificant, whereas QT dispersio n (QTd) and Q peak T dispersion (QpeakTd) values were significantly higher in the patient group (60+/-14, 54+/-14 ms, respectively) compared with the control group (42+/-10, 38+/-10 ms, respectively, p<0.001). Complex ventric ular arrhythmias (Lown Grade greater than or equal to III) in the IMVP grou p had a significant relationship with QTd and QpeakTd (p<0.001), but not wi th QT or QpeakT. As a result of the study, it is concluded that TVP accompa nying MVP does not increase the incidence of ventricular arrhythmia, that v entricular arrhythmia is related to QT dispersion rather than QT interval i n IMVP, that the QT dispersion is a fairly good marker for identifying the high-risk group for serious ventricular arrhythmia and sudden death, and th at QpeakT dispersion measurement is an additional indicator that could be a n alternative when QT is difficult to determine in conditions such as high heart rate or the presence of U wave.