Relation Between QT Dispersion and Ventricular Arrhythmias In Uncomplicated Isolated Mitral Valve Prolapse

Abstract

itral valve prolapse (MVP) is the most commonly diagnosed valvular heart disease, especially in the young, and affects 5% of the community. 1 Although it is reported that MVP has a good prognosis and a low incidence of complications, 2 it is obvious that even a rare complication will affect many individuals due to the high incidence of MVP in the general population. 3 However, some reports point out that these complications are not as rare as was thought, 4,5 the main entities being endocarditis, cerebrovascular accidents, sudden death, ventricular tachycardia and ventricular fibrillation. Arrhythmia and sudden death are significant complications in MVP cases; a 0.5% incidence of sudden death has been reported in different MVP studies 3,6 and it is suggested that the underlying mechanism of the sudden death is arrhythmogenic. It was also claimed that the prolonged QT intervals in MVP cases could be related to arrhythmia and sudden death. 7,8 Furthermore, there are studies that found that, instead of a prolonged QT interval increase, intrinsic QT dispersion can be related to arrhythmia in these cases. 9,10 In the present study, we aimed to determine the relationship between intrinsic QT dispersion and ventricular Japanese Circulation Journal Vol.63, December 1999 arrhythmias and sudden death in young individuals suffering from uncomplicated isolated MVP (IMVP). In this respect, cases without leaflet thickening (≥5 mm), severe mitral regurgitation or left ventricular systolic dysfunction were included in the study. Although a few reports have concentrated on the clinical significance of MVP accompanying tricuspid valve prolapse (TVP), the clinical significance of TVP and its relation to the arrhythmias of MVP has not yet been clearly documented. Therefore, we excluded MVP cases with accompanying TVP after beginning the study. Our main aim was to investigate the incidence and distribution of ventricular arrhythmias, according to their severity and relation to the QT interval, and to the dispersion of repolarization in uncomplicated IMVP. Methods Study GroupsThe current study was carried out in the Department of Cardiology, Faculty of Medicine, Dicle University between May 1996 and April 1998. We registered 91 individuals who underwent echocardiographic examination and were diagnosed as MVP; the group included 33 cases with accompanying TVP. Those patients who had disorders such as ischemic or rheumatic heart disease, systemic and/or pulmonary hypertension, diabetes mellitus, hyperthyroidism, stenotic valvular heart disease, congenital heart diseases, severe mitral regurgitation (>3 cm 2 regurgitant jet length in color flow mapping), or severe left ventricular dysfunction Jpn Circ J 1999; 63: 929 -933 (Received November 16, 1998; revised manuscript received July 16, 1999; accepted July 23, 1999 Complications of mitral valve prolapse (MVP), among which serious ventricular arrhythmia and sudden death are of major importance, affect many individuals due to the high incidence of MVP itself in the community despite t...

QT dispersion and ventricular arrhythmias in children with primary mitral valve prolapse

“…We found that QT dispersion and QTc increased as the degree of ventricular arrhythymias increased and QT dispersion was significantly higher in the group who had more than 10 VPBs in 24 hours and/or who had complex ventricular arrhythymias compared to healthy children who had no VPBs. Different results have been reported in studies related with QT interval in adults with primary MVP (7,8). Kulan et al (7) found no significant difference between adult patients with MVP and healty controls in terms of QTc.…”

“…In studies involving adults, a close relation between ventricular arrhythymias and QT dispersion which is a criterion for regional differences in the ventricular repolarization period has been reported (7)(8)(9). In the study of Kulan et al (7) which involved 64 adult patients with primary MVP and 80 healthy individuals, it was shown that QT dispersion increased in the patient group and there was a correlation between the increase in QT dispersion and complex ventricular arrhythymias.…”

“…Kulan et al (7) found no significant difference between adult patients with MVP and healty controls in terms of QTc. In the study of Ülgen et al (8) which involved 58 adult patients with primary MVP and 60 healthy individuals, it was shown that QTc was increased in the patient group. In the study of Çetinkaya et al (32) which involved 37 children with primary MVP and 26 healthy children, no significant difference was found between the patients and the control group in terms of QTc.…”

“…In studies involving adults, the frequency of ventricular arrhythmia in patients with primary MVP has been reported with a rate ranging between 49% and 89% depending on the patient group and MVP diagnostic criteria (21)(22)(23) Various causes have been proposed in formation of ventricular arrhythmias in primary MVP. These include stretching of the papillary muscles with ballooning prolapse of mitral leaflets (27), mechanical stimulation of the endocardium by thickened chordate (28), coronary emboly caused by accumulation of platalets and fibrin as a result of endocardial friction (29), autonomic dysfunction (30,31) and repolarization changes characterized by prolongation in QT interval and increase in QT dispersion (7)(8)(9).…”

“…It is thought that QT dispersion reflects regional differences in ventricular repolarization. In studies involving adults, it has been proposed that increased QT dispersion in patients with MVP is associated with ventricular arrhythmias, but QT length is not associated with ventricular arrhythmias (7)(8)(9). Heart rate variation examination is a method which is measured on 24-hour rhythm Holter monitoring and used in evaluation of the autonomic functions of the heart (10,11).…”