Accuracy of continuous photoplethysmography-based heart rate assessment during atrial fibrillation

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. AIM: Although mobile health tools using photoplethysmography (PPG) technology have been validated for the detection of atrial fibrillation (AF), their utility for heart rate assessment during AF remains unclear. Therefore, we aimed to evaluate the accuracy of continuous PPG-based heart rate assessment during AF. METHODS: Persistent AF patients were provided with Holter electrocardiography (ECG) (for ≥24 hours) simultaneously with a PPG-equipped smartwatch. Both the PPG-based smartwatch and Holter ECG automatically and continuously monitored patients’ heart rate/rhythm. ECG and PPG recordings were synchronised and divided into 1-minute segments from which a PPG-based and an ECG-based average heart rate estimation were extracted. RESULTS: In total, 47,661 simultaneous ECG and PPG 1-minute heart rate segments were analysed in 50 patients (34% women, age 73±8 years). The agreement between ECG-determined and PPG-determined heart rate was high (root-mean-squared error [RMSE]: 4.7 bpm). Heart rate estimated using PPG was accurate within ±10% in 93.7% of the corresponding ECG-derived heart rate segments. PPG-based heart rate estimation was more often accurate during night- (97%) than during day-time (91%, P<0.001) and during low levels (96%) compared to high levels of motion (92%, P<0.001). A neural network with a 10-minute history of the recording did not further improve the PPG-based heart rate assessment (RMSE: 4.4 [95% confidence interval: 3.5-5.2 bpm]. Only chronic heart failure was associated with a lower agreement between ECG-derived and PPG-derived heart rates (P=0.040). CONCLUSIONS: During persistent AF, continuous PPG-based heart rate assessment is feasible and shows high accuracy compared to Holter ECG. Motion and recording quality among other PPG-derived covariates did not introduce a systematic and correctable bias in the heart rate assessment. [Figure: see text]