Tehran University of Medical Sciences The Research in Heart Yield and Translational Medicine (RHYTHM) 3115-7270 17 3 2022 07 28 140 146 Mohadesse Ahmadi Amir-Kabir Hospital, School of Medicine, Arak University of Medical Sciences, Arak, Iran Bita Ghahremani Amirkabir Hospital, School of Medicine, Arak University of Medical Sciences, Arak, Iran Danial Habibi Instructor in Biostatistics, Department of Biostatistics, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran Saeid Sadrnia Department of Cardiology, School of Medicine, Arak University of Medical Sciences, Arak, Iran Yazdan Ghandi Pediatric Cardiologist, Amirkabir Hospital, Arak University of Medical Sciences, Arak, Iran 2021 03 23 2022 07 25 Background: Patients with mitral valve prolapse (MVP) may reveal symptoms of autonomic dysfunction and heart rate variability (HRV). We sought to explore the autonomic nervous system in children with MVP. Methods: This cross-sectional study enrolled 60 children aged between 5 and 15 years with MVP and 60 age- and sex-matched healthy children as controls. Two cardiologists performed electrocardiography and standard echocardiography. HRV parameters were explored via 24-hour rhythm 3-channel Holter monitoring. The depolarization of ventricular and atrial parameters, comprising QT max and min, QTc intervals, QT dispersion, P maximum and minimum, and P-wave dispersion, was measured and compared. Results: The mean age was 13.12±1.50 years in the MVP group (F/M: 34/26) and 13.20±1.81 years in the control group (F/M: 35/25). The maximum duration and P-wave dispersion in the MVP group were significantly different from the healthy children (P<0.001). The longest and shortest QT dispersion values and QTc values were significantly different between the 2 groups (P=0.004, P=0.043, P<0.001, and P<0.001, respectively). The HRV parameters were significantly different between the 2 groups, too. Conclusion: Decreased HRV and inhomogeneous depolarization showed that our children with MVP were prone to atrial and ventricular arrhythmias. Furthermore, P-wave dispersion and QTc could be used as prognostic markers of cardiac autonomic dysfunction before it is diagnosed by 24-hour Holter monitoring. https://rhythm.tums.ac.ir/index.php/jthc/article/view/1438 https://rhythm.tums.ac.ir/index.php/jthc/article/download/1438/1023