Is surface ECG a useful surrogate for subcutaneous ECG?

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Devices

Background:

• Surface electrocardiograms (ECGs) are often used as surrogates for subcutaneous ECGs to assess implantable devices.
• However, the accuracy and limitations of surface ECGs compared to subcutaneous ECGs are not fully understood.

Purpose of the Study:

• To evaluate the correlation and signal quality between surface and subcutaneous ECGs in patients with Reveal Plus devices.
• To determine the suitability of surface ECGs as surrogates under various physiological conditions and maneuvers.

Main Methods:

• Surface electrodes were placed over subcutaneous Reveal Plus electrodes in 48 participants.
• Simultaneous surface and subcutaneous ECG recordings were obtained during rest, isometric myopotential noise, and artifact-inducing maneuvers.

Main Results:

• High correlation (R=0.96) and similar signal-to-noise ratio (SNR) were observed between surface and subcutaneous ECGs at rest.
• During myopotential noise, high correlation (R=0.91) and comparable SNR were maintained.
• During artifact-inducing maneuvers, correlation decreased (R=0.82-0.93), and subcutaneous ECGs demonstrated significantly higher SNR than surface ECGs (P < 0.05).

Conclusions:

• Surface ECGs are suitable surrogates for subcutaneous ECGs in artifact-free conditions.
• Subcutaneous ECGs provide superior signal quality and artifact resistance during maneuvers involving device or electrode movement.
• The findings highlight the limitations of surface ECGs in dynamic situations and emphasize the value of subcutaneous monitoring.