Evaluation of heart rate variability in pediatric patients with beta thalassemia major: Cross-sectional study

Abstract

BACKGROUND Cardiac complications are a significant cause of morbidity and mortality in patients with β-thalassemia major (TM). Early detection of subclinical cardiac involvement remains challenging, as conventional echocardiography and electrocardiography often fail to identify early dysfunction. Heart rate variability (HRV) reflects autonomic regulation of the heart and may serve as a sensitive marker for early cardiac impairment. AIM To evaluate HRV in children with β-TM without clinical cardiac manifestations. METHODS A cross-sectional study was conducted on 40 children with β-TM and 40 age- and sex-matched healthy controls. All participants underwent full clinical assessment, laboratory investigations, and 24-hour ambulatory Holter monitoring. HRV parameters were analyzed in both time and frequency domains using Cardioscan CS12 software. Statistical comparisons between groups and correlations with hemoglobin and serum ferritin levels were performed using SPSS version 27. RESULTS Children with β-TM showed significantly higher minimum and maximum heart rates and markedly lower HRV indices, including standard deviation of all normal-to-normal intervals (SDNN), standard deviation of the 5-minutes average normal-to-normal intervals, SDNN index, root mean square of successive differences, and percentage of normal-to-normal intervals differing by > 50 ms, compared with controls (P < 0.001). High-frequency (HF) power was significantly decreased, whereas the low-frequency/HF ratio was elevated (P < 0.001), indicating sympathetic predominance. Arrhythmias were recorded in 47.5% of patients, though HRV parameters did not differ significantly between those with and without arrhythmia. No correlation was found between HRV indices and hemoglobin or serum ferritin levels. CONCLUSION Children with β-TM demonstrate significant autonomic imbalance, reflecting early cardiac involvement even before the onset of clinical symptoms. Routine HRV assessment could provide a valuable, non-invasive tool for early detection and risk stratification in pediatric thalassemia management.