Detecting episodes of brady- and tachycardia using photo-plethysmography at the wrist in free-living conditions

Detecting episodes of bradycardia and tachycardia can help identifying the clinical relevance of common cardiac symptoms. This study aimed at investigating whether an unobtrusive wrist-wearable device equipped with a photo-plethysmographic (PPG) and acceleration sensor could be used to detect such rate abnormalities in free-living conditions. Twenty patients (M=55%, age: 67 ± 13 y) reporting cardiac symptoms were monitored for 24 hours in free-living conditions using a portable Holter ECG recorder. Simultaneously, a wrist-wearable device equipped with a PPG and acceleration sensor was used to measure heart rate and the mean inter-pulse-interval (IPI) in 5-sec epochs. ECG-derived inter-beat-intervals (IBI) were used as ground truth for determining episodes of bradycardia (>1200 ms) and tachycardia (<500 ms) during the monitoring period. According to the ECG, the duration of brady- and tachycardia and normal rate lasted a total of 766 min, 64 min, and 27024 min, respectively. Average IPI during bradycardia and tachycardia was 1310 ± 80 ms and 459 ± 37 ms, respectively. IPI data correctly identified episodes of bradycardia (Se: 85.0%, Sp: 99.4%) and tachycardia (Se: 89.1%, Sp: 99.9%). In conclusion, a wrist-wearable device equipped with a PPG sensor can accurately detect rate abnormalities such as brady- and tachycardia in free-living conditions.