From Wires to Wearables (1): Clinical equivalence with an Axis-Aware Validation of a Wearable ECG System (Sydäntek) with Compressed Lead Geometry

Conventional 12-lead electrocardiogram (ECG) systems, reliant on wired configurations and distal limb electrodes, restrict patient mobility and hinder continuous monitoring. Recent advances in wearable ECG aim to deliver diagnostic-grade fidelity in ambulatory settings. Sydäntek—a compact wearable ECG developed by Carditek Medical Devices—addresses these limitations by compressing Einthoven’s triangle into a 5 × 5 cm patch positioned at the left shoulder crease. This novel geometry enables full 12-lead acquisition without compromising signal fidelity. In a clinical comparison with a standard ECG system (Welch Allyn CardioPerfect™), Sydäntek’s performance was evaluated using Bland–Altman analysis and polar histogram visualization across a stratified population. Patients were grouped by baseline QRS axis into three ranges (−30° to 0°, 0° to +45°, and +45° to +90°) to assess axis-dependent variability. Sydäntek demonstrated consistent waveform morphology and a predictable QRS axis rotation (∼ +14°), attributable to anterior repositioning of limb leads. Polar histograms revealed a leftward skew without significant outliers. Subgroup Bland–Altman analysis showed systematic, baseline-dependent variability: the 0° to +45° group exhibited the narrowest limits of agreement, while the −30° to 0° cohort displayed greater dispersion. Applying a +14° correction effectively minimized axis bias within the clinically relevant −30° to +90° range, preserving diagnostic waveform integrity. Overall, Sydäntek achieves clinical equivalence with standard ECG through a geometry-driven axis adaptation that is consistent, manageable, and clinically acceptable. Its compact, wire-free form factor enables high-fidelity cardiac monitoring in real-time ambulatory settings—demonstrating that spatial innovation can coexist with gold-standard diagnostics and advance the ECG into wearable practice.