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

Abstract

Aim: To investigate ventricular arrhythmias in children with primary mitral valve prolapse and to evaluate its relation with QT length, QT dispersion, autonomic function tests and heart rate variability measurements. Material and Methods:Fourty two children with mitral valve prolapse and 32 healthy children were enrolled into the study. Twelve-lead electrocardiograms, autonomic function tests, echocardiography and 24-hour rhythm Holter tests were performed. Electrocardiograms were magnified digitally. The QT length was corrected according to heart rate. The patients were grouped according to the number of premature ventricular contractions and presence of complex ventricular arhythmia in the 24-hour rhythm Holter monitor test. Heart rate variability measurements were calculated automatically from the 24-hour rhythm Holter monitor test. Orthostatic hypotension and resting heart rate were used as autonomic function tests. Results:The mean age was 13.9±3.3 years in the patient group and 14.6±3.1 years in the control group (p>0.05). Thirty four of the patients (81%) were female and eight (19%) were male. Twenty five of the control subjects (78%) were female and seven (22%) were male. The QT dispersion and heart rate corrected QT interval were found to be significantly increased in the children with primary mitral valve prolapse when compared with the control group (56±16 ms vs. 43±11 ms, p=0.001; 426±25 ms vs. 407±26 ms, p=0.002, respectively). In 24-hour rhythm Holter monitor tests, ventricular arrhythmias were found in 21 out of 42 patients (50%) and 6 out of 32 control subjects (18.8%) (p=0.006). QT dispersion was found to be significantly increased in patients with premature ventricular contractions ≥ 10/day and/or complex ventricular arrhythmias compared to the control group without ventricular premature beats (p=0.002). There was no significant difference in autonomic function tests and heart rate variability measurements between the patient and control groups. Conclusions:The noted increase in QT dispersion may be a useful indicator for the clinician in the evaluation of impending ventricular arrhythmias in children with primary mitral valve prolapse. (Turk Pediatri Ars 2016; 51: 135-41)

Effects of Mitral Valve Prolapse on Heart Rate Variability and the Autonomic Nervous System in Children

“…We revealed that increased QT dispersion and impaired HRV occur in children with primary MVP. This does not chime in with the findings reported by Ebru Yalın İmamoğlu et al 10 Moreover, QTc and QT dispersion were increased with a rise in the extent of ventricular arrhythmias, but the difference was not statistically significant. We believe that controversial results concerning QT interval could be attributed to the application of diverse measurement techniques in various studies and the difficulty of determining the end of the T wave.…”

“…ST-T changes with a prevalence rate of 30% were reported in children with primary MVP. Likewise, Ebru Yalın İmamoğlu et al 10 reported that the rate of ST-T changes in their patients was 28.5%. In the present study, however, we did not assess ST-T changes.…”

“…According to Ebru Yalın İmamoğlu et al, 10 children with primary MVP and subjects in the control group were significantly different concerning HRV. Furthermore, there was no significant difference between the patient group split by the number of VPBs recorded during 24-hour Holter monitoring and the existence of complicated ventricular arrhythmias and the control group.…”

“…The sample size was calculated using the Stata 11 software at 95% levels of the confidence interval and a power of 80% based on the results of a similar study. 10 Inclusion criteria were age between 5 and 15 years, appropriate echocardiography views, the displacement of the anterior and posterior mitral leaflets more than 2 mm from the mitral annulus, normal heart structure and function without congenital heart diseases, no history of cardiac arrhythmias, and no treatment with antiarrhythmic drugs. Patients whose MVP was linked to secondary causes such as Marfan syndrome, rheumatic heart disease, Ehlers–Danlos syndrome, infective endocarditis, cardiomyopathy, atrial septal defect, and anorexia nervosa and patients who consumed antiarrhythmic drugs or had prolonged QT intervals were excluded from the study.…”