Active pediatric cancer therapy was associated with more regular and persistent heart rate dynamics, including a significantly higher T2RR (median 22.04 vs 17.52; p=0.0047), compared to post-treatment surveillance.
Cross-Sectional (n=40)
No
Does active cancer treatment alter linear and nonlinear heart-rate and QT-interval variability compared to post-treatment surveillance in pediatric cancer patients?
Combined RR and QTc recurrence-quantification analysis from short ECGs reveals stage-specific nonlinear cardiac dynamics in pediatric cancer patients, highlighting lower RR complexity during active therapy.
Absolute Event Rate: 22.04% vs 17.52%
p-value: p=0.0047
Abstract Pediatric cancer therapy may perturb autonomic and ventricular repolarization control. We tested whether short-term electrocardiograms (ECGs) reveal stage-specific nonlinear cardiac dynamics between active treatment ( T ) and post-treatment surveillance ( S ), and whether recurrence-quantification analysis (RQA) adds physiological information beyond linear indices. In 40 children diagnosed with cancer ( T = 20, S = 20), we recorded 5-min, supine, lead-II ECGs during routine visits. R-peaks, QRS onset, and T -wave offset were identified to construct beat-to-beat RR and QT-interval series; QTc was derived beatwise using a power-law rate correction. We computed linear indices (RR mean , SDRR, RMSSD, pNN50; QT mean , SDQT; QTc mean , SDQTc) and RQA indices (DET, L, ENTR, LAM, TT, VMAX, T1, T2) for RR, QT, and QTc. The S group showed a longer RR interval (slower sinus rate) and higher short-term vagal indices (RR mean , p = 0.0112; RMSSD, p = 0.0375; pNN50, p = 0.0277). QT and QTc were longer in S (QTc mean , p = 0.0375). In contrast, RR RQA indicated more regular/persistent dynamics in T , with the strongest separation in T2 RR ( p = 0.0047), consistent with slower returns to distinct states. QT-RQA showed no differences, but QTc–RQA revealed longer trapping structure in T (TT QTc , p = 0.0171), implying rate-masked repolarization organization that emerges after correction. Thus, active therapy was associated with lower RR complexity, whereas follow-up was characterized by higher vagal-related indices and longer repolarization intervals. Crucially, QTc analysis revealed the only nonlinear differences, underscoring the need for beatwise rate correction. Combined RR–QTc–RQA from short ECGs may provide a stage-aware, noninvasive biomarker of cardiac well-being in pediatric oncology and warrants validation in larger, exposure-stratified longitudinal cohorts.
Reyes–Lagos et al. (2026) conducted a cross-sectional in Pediatric cancer (n=40). Active cancer treatment vs. Post-treatment surveillance was evaluated on Recurrence times of the second type for RR intervals (T2RR) (p=0.0047). Active pediatric cancer therapy was associated with more regular and persistent heart rate dynamics, including a significantly higher T2RR (median 22.04 vs 17.52; p=0.0047), compared to post-treatment surveillance.