The in-ear region as a novel anatomical site for ECG signal detection: validation study on healthy volunteers.

Purpose: Early detection of cardiac arrhythmias is a major opportunity for mobile health, as wearable devices nowadays available can detect single-lead electrocardiogram (ECG). The study aims to validate the in-ear region as a new anatomical site for ECG signal detection and looks towards designing innovative ECG wearable devices.

Methods: We performed ECG using KardiaMobile device (AliveCor®) on 35 healthy volunteers. First, ECG was detected by standard modality using both hands. Then, ECG was detected using the left in-ear region instead of the right hand. All the recorded ECGs were analyzed by the device and by two cardiologists in blind testing.

Results: We successfully collected 70 ECGs performed on 35 volunteers (male 54%, age 39.1 ± 10.7 years; BMI 22.9 ± 2.89 kg/m) with no differences observed by KardiaMobile in ECG reports detected in the two different modalities. All the ECGs were reported as normal by the device and the two cardiologists. Moreover, linear regression analysis showed good correlation between the amplitude (mV) of P (r = 0.76; r = 0.57; p < 0.0001) and QRS waves (r = 0.81; r = 0.65; p < 0.0001), the intervals (ms) of PR (r = 0.91; r = 0.83; p < 0.0001; LOA - 0.60-0.41; CC = 0.91), QRS (r = 0.78; r = 0.61; p < 0.0001; LOA - 0.49-0.43; CC = 0.78), QT (r = 0.85; r = 0.71; p < 0.0001; LOA - 1.31-1.20; CC = 0.85), and heart rate (r = 0.94; r = 0.89; p < 0.0001; LOA - 7.82-7.76; CC = 0.94) detected in two different modalities.

Conclusion: The in-ear region is a reliable novel anatomical site for ECG signal detection in normal healthy subjects. Further studies are needed to validate this new ECG detection modality also in case of cardiac arrhythmias and to support the development of new wearable devices.