Low Iron Stores in Otherwise Healthy Children Affect Electrocardiographic Markers of Important Cardiac Events

Does Iron Deficiency Affect the Heart in Children?

INTRODUCTION

It is well known that serum iron parameters are closely related to cardiovascular health. Iron deficiency may lead to significant cardiac problems, such as atrioventricular conduction abnormalities, and systolic and/or diastolic dysfunction. Studies related to the effect of iron deficiency on cardiac functions are limited in children. Therefore, the aim of this study was to evaluate the effect of low iron stores on cardiac repolarization parameters which are used to predict arrhythmia and cardiac functions.

MATERIALS AND METHODS

Onehundred thirty-five children 2 to 18 years of age without structural heart disease who were referred to the Pediatric Cardiology Department for various reasons such as chest pain, heart murmur, or evaluation before sports participation were evaluated prospectively. The cases were separated into 3 groups according to ferritin levels (group 1: ferritin <15 ng/mL [n=48], group 2: ferritin 15 to 25 ng/mL [n=51], and group 3: ferritin >25 ng/mL [n=36]). Evaluations were made with detailed 12-lead surface electrocardiography (ECG) and transthoracic echocardiogram. Cardiac repolarization parameters were measured from surface ECG and systolic functions, left ventricular wall diameters were evaluated from transthoracic echocardiogram.

RESULTS

Eighty-four (62.2%) girls and 51 (37.8%) boys are included in the study. The average age of the groups was similar. In children with low ferritin levels (group 1); Pw, Pw max, and Pw dis; QT, QTc, and QTc dis; Tp-Te, Tp-Te dis, Tp-Te/QT, and Tp-Te/QTc were significantly longer compared with the group 3 (P<0.05). There was a negative correlation between ferritin level and Pw, P max, and Pw dis; QT, QT dis, QTc, and QTc dis; Tp-Te, Tp-Te dis, Tp-Te/QT, and Tp-Te/QTc (P<0.05). No correlation was found between ferritin level and Pw min. There was no difference between the groups in respect of ejection phase indices, heart wall measurements, and end-diastolic diameter measurements.

CONCLUSION

Iron deficiency may be related to the tendency of arrhythmias in children without structural heart disease. Therefore, careful evaluation of ECG parameters of healthy children with low iron stores, and follow up with intermittent monitoring is highly important.

Prolonged QTc Interval in Nigerian Children with Sickle Cell Anemia

Prolonged QTc interval, a risk factor for ventricular arrhythmia, occurs in sickle cell anemia. The aim of this study was to determine the risk of prolonged QTc interval and its relationship with vaso-occlusive painful crises (VOCs) and follow-up steady-state in the same children with sickle cell anemia. This prospective cohort study enrolled 38 subjects, aged 5-17 years. History of bone pain and examination were obtained during VOC and steady-state. Assessment of QTc interval was with 12-lead electrocardiography. The QTc interval value >0.440 seconds was taken as prolonged. Median (interquartile range) of QTc interval was higher during VOC [0.447 (0.438-0.459) seconds] than during steady-state [0.435 (0.417-0.440) seconds]. Risk of prolonged QTc interval was higher during VOC (68.4%) than in steady-state (21.1%) with relative risk of 3.250 [95% confidence interval (CI) = 1.692-6.241]. Prolonged QTc interval was likely to occur [area under curve (AUC) = 0.759, p<0.001] during VOC with 68.4% sensitivity, 78.9% specificity and at cutoff point of 0.441 seconds. Prolonged QTc interval negatively correlated with packed cell volume (PCV) during VOC [r_s (36) = -0.14, p = 0.387]. Binary logistics of the combined effect of PCV and gender on QTc interval showed that during VOC, males were more likely to have prolonged QTc [odds ratio (OR): 1.337 (95% CI: 0.327-5.464; p = 0.686]. Children with sickle cell anemia, particularly males, were three-times more likely to have prolonged QTc interval during VOC when QTc interval was >0.441 seconds. Routine electrocardiography may help to identify those with QTc intervals above this threshold for prompt cardiac-oriented management.

The effect of low iron storage without Anaemia on electrocardiography

BACKGROUND

Low iron storage is a common health problem around the world. Although the association of low iron storage with cardiovascular events and various electrocardiographic parameters has been investigated, its association with fragmented QRS (fQRS), T_peak-T_end (Tp-e) interval, Tp-e/QT and Tp-e/QTc ratios, which are important criteria for repolarization, has not been studied in adults.

METHODS

A total of 201 female patients in the 18-50 age group with no history of chronic and cardiac disease or anaemia were included in the study. Patients were divided into 3 groups based on their ferritin levels. Twelve lead EKGs were obtained from each patient, and fQRS, Tp-e interval, Tp-e/QT and Tp-e/QTc ratios were calculated manually.

RESULTS

A total of 201 female patients with an average age of 37 ± 9 were included in the study. Group 1 (ferritin<15 ng/mL) consisted of 79 (39.3%) patients, Group 2 (ferritin 15-30 ng/mL) consisted of 64 patients (31.8%) and Group 3 (ferritin≥30 ng/mL) consisted of 58 (28.9%) patients. Tp-e interval was significantly higher in Group 1 compared to Group 2 and 3 (p < 0.001). A similar relationship was also observed between Tp-e/QT, Tp-e/QTc and fQRS (p < 0.001). A moderate, negative relationship was found in the correlation analysis of Tp-e, Tp-e/QT, Tp-e/QTc and fQRS with ferritin value [r = -0.519 (p = 0.001), r = -0.485 (p = 0.001), r = -0.540 (p = 0.001) and r = -0.345 (p = 0.001), respectively].

CONCLUSION

As a result of the study, it was found that low iron storage may increase arrhythmogenic susceptibility through increased fragmented QRS presence, increased Tp-e interval, Tp-e/QT and Tp-e/QTc ratios in healthy women of childbearing age.

Evaluation of electrocardiographic markers of cardiac arrhythmic events and their correlation with cardiac iron overload in patients with β-thalassemia major

Iron overload is associated with an increased risk of atrial and ventricular arrhythmias. Data regarding the relationship between electrocardiographic parameters of atrial depolarisation and ventricular repolarisation with cardiac T2* MRI are scarce. Therefore, we aimed to investigate these electrocardiographic parameters and their relationship with cardiac T2* value in patients with β-thalassemia major. In this prospective study, 52 patients with β-thalassemia major and 52 age- and gender-matched healthy patients were included. Electrocardiographic measurements of QT, T peak to end interval, and P wave intervals were performed by one cardiologist who was blind to patients' data. All patients underwent MRI for cardiac T2* evaluation. Cardiac T2* scores less than 20 ms were considered as iron overload. P wave dispersion, QTc interval, and the dispersions of QT and QTc were significantly prolonged in β-thalassemia major patients compared to controls. Interestingly, we found prolonged P waves, QT and T peak to end dispersions, T peak to end intervals, and increased T peak to end/QT ratios in patients with T2* greater than 20 ms. No significant correlation was observed between electrocardiographic parameters and cardiac T2* values and plasma ferritin levels. In conclusion, our study demonstrated that atrial depolarisation and ventricular repolarisation parameters are affected in β-thalassemia major patients and that these parameters are not correlated with cardiac iron load.