A Novel Wearable Device for Continuous Ambulatory ECG Recording: Proof of Concept and Assessment of Signal Quality

Figures

• 

  Figure 1. OMgarments are biointeractive wearable ECG sensors. The OMsignal garments represent a novel type of wearable ECG sensors and consist of two different products: The OMshirt (men) (A) and the OMbra (women) (B). Both garments are intended to be worn as underwear and contain integrated, silicone-based sensors that are in contact with the skin recording a single-lead ECG corresponding to a modified V5-lead. The ECG sensors are connected to the acquisition module (C) through five snaps (D). The acquisition module has the capacity to save or process ECG signals for real-time or offline analysis.

• 

  Figure 2. ECG samples of simultaneous recording with OMgarments and Holter. Shown are two samples of simultaneous recording with the OMgarment and a standard 3-lead Holter. The precise beat-to-beat signal coverage of the OMgarment allows even detection of subtle rhythm phenomena, such as respiratory sinus arrhythmia. Note the perfect signal overlay between Holter and garment and high signal quality of the ECG tracings from the OMgarments. The displayed ECG tracings from the OMgarment represent unfiltered signals without additional modification to improve signal quality.

• 

  Figure 3. Signal coverage of OMgarments and Holter. Shown is the average signal coverage over 24 h for any given R-R interval (A–C) and for any given time point during recording (D–E). Note the almost perfect overlay of signal coverage between OMgarments and Holter recordings.

• 

  Figure 4. Bland-Altman analysis for signal coverage. (A) The overall signal coverage by the OMgarment was excellent, showing an almost perfect overlay compared to standard Holter recording with a mean difference in heart rate of only 2 ± 5 bpm. The quality of signal coverage with OMgarments showed no difference between women (B) and men (C) and was equivalent to Holter recording.

• 

  Figure 5. Accuracy of signal morphology by semi-quantitative assessment. Shown are histograms of a Kolmogorov distribution derived from the combined score ranking of the averaged semi-quantitative assessment of the overall morphology accuracy of ECG signals recorded by Holter and the OMgarments. Each histogram displays the proportion and degree of diagnostic bins of recordings with the OMgarments compared to Holter regarding the overall accuracy (A) and signal quality of P, QRS, and T (B–D). Diagnostic bins are presented as stacked columns containing the data for males (OMshirt) and females (OMbra). All diagnostic bins below the prespecified noninferiority margin of 15% indicate that the signal quality of the OMgarment was as good as the Holter recording. (A) The overall signal accuracy was noninferior to the Holter recording, but the results were largely driven by recordings in females. Overall signal quality in males was inferior to Holter recording in up to 75% of recordings, mostly related to high levels of noise (please see Section 3.5) and inferior P-wave quality (B). Signal quality of QRS complexes (C) and T-waves (D) were also significantly better in females compared to males.