Evaluation of heart rate variability in patients with thalasemia major

Objective: Cardiac complications due to the iron overload in patients with thalassemia major are the leading cause of death. In our study, we aimed to investigate the usability of heart rate variability (HRV) due to accumulation of iron in early cardiac involvement and the risk of arrhythmia in children with thalassemia major and non-invasive method of demonstrating the credibility of the HRV. Materials and Methods: This study was performed between October 2012 and August 2013 in Dicle University Faculty of Medicine, Department of Pediatrics. The 24-hour holter electrocardiography of 30 patiens with beta-thalassemia major and 30 healthy control subjects with a diagnosis were examined. Time and frequency indices of heart rate variability in the two groups were compared. The relationship between serum ferritin levels and HRV parameters were evaluated. Results: Patients with thalassemia major were 16 girls (53%) and 14 men (47%) and the mean age was 10.1 ± 3.8 years. The maximum heart rate, SDNN, SDNN index, RMSSD, pNN50, TP, LF and VLF parameters of 24-hour Holter ECG parameters were significantly lower in the patient group than the control group. Patients were divided into three groups according to ferritin levels as Group I (ferritin levels between 1500 ng/ml and 2500 ng/ml), Group II (ferritin levels between 2501 ng/ml and 5000 ng/ml), Group III (ferritin levels above 5000 ng/mL). The groups allocated in accordance with the ferritin values and HRV parameters were compared. The maximum heart rate in Group I were significantly higher than Group II and Group III (p=0,03). There was no significant difference between the groups in the other parameters. Ectopic beats were determined in eight patients. In holter ECG atrial or ventricular ectopic beats revealed in four of 24 patients with normal echocardiographic findings. Conclusion: Ferritin values were not useful in monitoring the cardiac functions and electrical changes. Autonomic dysfunction, atrial and/or ventricular premature beats can be detected before cardiac involvement in echocardiography. Therefore we think echocardiographic examination on an annual basis as well as the implementation of 24-hour holter ECG should be applied to the patients with thalassemia major especially from second decade of life.