Atrial and Ventricular Electrocardiographic Dromotropic Disturbances in Down Syndrome Patients with Structurally Normal Heart: A Cross-Sectional Study

Authors

1 Assistant Professor, Department of Pediatric Cardiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran.

2 Assistant Professor, Department of Cardiovascular Surgery, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran.

3 Master of Sciences in Biostatistics, Department of Biostatistics and epidemiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran.

4 Assistant Professor, Department of Neonatology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran.

5 Assistant Professor, Department of Pediatrics, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran.

6 General Practitioner, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran.

Abstract

Background: We designed a cross-sectional study to determine electrocardiographic disorders in Down syndrome patients with congenitally normal hearts in a bid to predict fatal cardiac arrhythmia in the future.
Materials and Methods: We investigated 60 children with DS without congenital abnormal hearts. Sixty healthy juveniles were also included in the study as a control group. Physical examination, electrocardiography, and echocardiography were performed in all subjects. Corrected QT interval (QTc) was measured according to Bazett’s formula.
Results: Patients with DS consisted of 32 males (53.33%), and 28 females (46.66%), aged 6–13 (9.21 ± 6.24) years old. Healthy subjects comprised 31 males (51.66%), and 29 females (48.33%) with a mean age of 9.15 ± 5.01. The two groups were significantly different in terms of heart rate (P=0.006), maximum P-wave duration (P=0.001), and P-wave dispersion (PWd, P=0.0001). There was no statistically significant difference regarding minimum P-wave duration (P=0.176). The patients with DS had a greater maximum QTc interval, QT dispersion, and corrected QT interval dispersion (QTc-d) than the healthy control subjects (P=0.001). However, there was no difference in maximum QT interval and minimum QTc interval between the two groups (P=0.67 and P=0.553, respectively). A positive correlation was found between age, heart rate, and all electrocardiographic variables.
Conclusion: All DS patients, even in the absence of concomitant congenital heart disease should be followed up carefully by electrocardiography, looking for increased PWd and QTc-d to detect predisposed cases to arrhythmia.

Keywords