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

Abstract

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.

Received: 20 July 2025 | Revised: 8 September 2025 | Accepted: 25 September 2025

Conflicts of Interest

The authors declare that they have no conflicts of interest to this work.

Data Availability Statement

Data are available from the corresponding author upon reasonable request.

Author Contribution Statement

Sugandhi Gopal: Conceptualization, Methodology, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration. Prabhavathi Bhat: Validation. Sharada Sivaram: Validation. V J Karthikeyan: Validation. Mukund Prabhu: Validation. Mohith Subramanian: Methodology, Software, Formal analysis, Investigation, Data curation, Writing – review & editing, Visualization. Vishwateja Reddy: Software, Formal analysis, Investigation. Aishwarya Srinivasan: Software, Formal analysis, Investigation.