Key result
Apple Watch correlates with ECG heart rates in ~75% of AF events, outperforming Fitbit.
Why the study?
Paroxysmal AF often goes uncaptured despite causing stroke, prompting evaluation of PPG-integrated wearable devices to immediately detect paroxysmal AF.
Do Apple Watch and Fitbit PPG sensors accurately measure pulse rate during atrial fibrillation compared to telemetric ECG in postoperative cardiac surgery patients?
Observational (n=40)
No
Do Apple Watch and Fitbit PPG sensors accurately measure pulse rate during atrial fibrillation compared to telemetric ECG in postoperative cardiac surgery patients?
Absolute Event Rate: 75% vs 30%
Apple Watch in workout mode provides more accurate pulse rate measurements during atrial fibrillation than Fitbit when compared to telemetric ECG.
May support Apple Watch over Fitbit for postoperative AF pulse tracking; hypothesis-generating and requires prospective validation before practice change.
BACKGROUND Wearable devices with photoplethysmography (PPG) technology can be useful for detecting paroxysmal atrial fibrillation (AF), which often goes uncaptured despite being a leading cause of stroke. OBJECTIVE This study is the first part of a 2-phase study that aimed at developing a method for immediate detection of paroxysmal AF using PPG-integrated wearable devices. In this study, the diagnostic performance of 2 major smart watches, Apple Watch Series 3 and Fitbit (FBT) Charge HR Wireless Activity Wristband, each equipped with a PPG sensor, was compared, and the pulse rate data outputted from those devices were analyzed for precision and accuracy in reference to the heart rate data from electrocardiography (ECG) during AF. METHODS A total of 40 subjects from patients who underwent cardiac surgery at a single center between September 2017 and March 2018 were monitored for postoperative AF using telemetric ECG and PPG devices. AF was diagnosed using a 12-lead ECG by qualified physicians. Each subject was given a pair of smart watches, Apple Watch and FBT, for simultaneous pulse rate monitoring. The heart rate of all subjects was also recorded on the telemetry system. Time series pulse rate trends and heart rate trends were created and analyzed for trend pattern similarities. Those trend data were then used to determine the accuracy of PPG-based pulse rate measurements in reference to ECG-based heart rate measurements during AF. RESULTS Of the 20 AF events in group FBT, 6 (30%) showed a moderate or higher correlation (cross-correlation function>0.40) between pulse rate trend patterns and heart rate trend patterns. Of the 16 AF events in group Apple Watch (workout [W] mode), 12 (75%) showed a moderate or higher correlation between the 2 trend patterns. Linear regression analyses also showed a significant correlation between the pulse rates and the heart rates during AF in the subjects with Apple Watch. This correlation was not observed with FBT. The regression formula for Apple Watch W mode and FBT was X=14.203 + 0.841Y and X=58.225 + 0.228Y, respectively (where X denotes the mean of all average pulse rates during AF and Y denotes the mean of all corresponding average heart rates during AF), and the coefficient of determination (R2) was 0.685 and 0.057, respectively (P<.001 and .29, respectively). CONCLUSIONS In this validation study, the detection precision of AF and measurement accuracy during AF were both better with Apple Watch W mode than with FBT.
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Inui et al. (2019) conducted an observational in paroxysmal atrial fibrillation (n=40). Apple Watch Series 3 vs. Fitbit Charge HR Wireless Activity Wristband was evaluated on moderate or higher correlation (cross-correlation function>0.40) between pulse rate and heart rate trend patterns during AF. Apple Watch (workout mode) showed a moderate or higher correlation with ECG heart rates in 75% of AF events compared to 30% with Fitbit.
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