Feasibility and diagnostic agreement of Apple Watch and KardiaMobile electrocardiograms compared with standard 12-lead ECG in children

Mobile electrocardiogram (ECG) technologies such as the Apple Watch (AW) and KardiaMobile 6 L (KM) are increasingly used in adult cardiology, yet their performance in pediatric populations remains underexplored. This study aimed to evaluate the feasibility, tracing quality, and diagnostic agreement of AW and KM compared to standard 12-lead ECG (S12L) in children. We conducted a prospective observational study in children aged 4–17 years undergoing routine ECG evaluation. All 12 leads were reconstructed using alternative device positioning for both AW and KM. ECGs were independently analyzed by blinded pediatric cardiologists for standard parameters, rhythm interpretation, and tracing quality. A total of 30 patients were enrolled. Median acquisition times differed significantly across devices: 4 min (2;10 min; S12L), 5 min (4;10 min; KM), and 15 min (10;32 min; AW). KM yielded high tracing quality (median 9/10), comparable to standard ECG, while AW showed lower quality (median 6/10). Strong to very strong correlations (r = 0.6–0.96, p < 0.001) with standard ECGs were found for QRS axis, R and S wave voltages, and QT intervals. Both devices detected arrhythmic events. Mobile ECG devices showed strong agreement with standard ECG for selected parameters (e.g., QRS axis, major voltages), while other intervals demonstrated weaker correlation. Findings should be interpreted within the context of a small sample size and feasibility-oriented study. KM demonstrated higher signal quality and faster acquisition, while AW was limited by longer acquisition time and artifact sensitivity. Mobile ECG devices offer promising tools for pediatric arrhythmia diagnostics, although pediatric-specific adaptations are warranted.