Continuous 24-h Photoplethysmogram Monitoring Enables Detection of Atrial Fibrillation

Abstract

Aim: Atrial fibrillation (AF) detection is challenging because it is often asymptomatic and paroxysmal. We evaluated continuous photoplethysmogram (PPG) for signal quality and detection of AF. Methods: PPGs were recorded using a wrist-band device in 173 patients (76 AF, 97 sinus rhythm, SR) for 24 h. Simultaneously recorded 3-lead ambulatory ECG served as control. The recordings were split into 10-, 20-, 30-, and 60-min time-frames. The sensitivity, specificity, and F1-score of AF detection were evaluated for each time-frame. AF alarms were generated to simulate continuous AF monitoring. Sensitivities, specificities, and positive predictive values (PPVs) of the alarms were evaluated. User experiences of PPG and ECG recordings were assessed. The study was registered in the Clinical Trials database (NCT03507335). Results: The quality of PPG signal was better during night-time than in daytime (67.3 ± 22.4% vs. 30.5 ± 19.4%, p < 0.001). The 30-min time-frame yielded the highest F1-score (0.9536), identifying AF correctly in 72/76 AF patients (sensitivity 94.7%), only 3/97 SR patients receiving a false AF diagnosis (specificity 96.9%). The sensitivity and PPV of the simulated AF alarms were 78.2 and 97.2% at night, and 49.3 and 97.0% during the daytime. 82% of patients were willing to use the device at home. Conclusion: PPG wrist-band provided reliable AF identification both during daytime and night-time. The PPG data's quality was better at night. The positive user experience suggests that wearable PPG devices could be feasible for continuous rhythm monitoring.

Keywords: algorithms; atrial fibrillation; monitoring; photoplethysmogram; photoplethysmography; quality; screening; signal quality analysis.

Figure 1

Standards for Reporting Diagnostic Accuracy Studies (STARD) flow diagram of the study patient flow. A total of 654 patients were screened in Kuopio University Hospital. 200 patients were initially recruited, and 173 patients were accepted in the final study population. Abbreviations: AF, atrial fibrillation; ECG, electrocardiogram; SR, sinus rhythm; PPG, photoplethysmography; and RBBB, right bundle branch block. STARD 2015 checklist and information about STARD 2015 is presented in Supplementary Material.

Figure 2

Example recordings of PPG (red) and ECG (gray) signals. (A) shows recordings of a patient in SR, and (B) in AF.

Figure 3

AF detection performance and PPQ quality. (A) shows AF detection mean sensitivity (blue) and PPV (green) calculated for each hour of day. Simultaneous 3-lead ambulatory ECG recording served as rhythm control. Hourly analyzable PPG data amount is shown with solid red line, and median quartiles with dashed red line. (B) shows F1-scores for patient-based AF detection for AF detection time-frames of 10, 20, 30, and 60 min. AF, atrial fibrillation; AM, ante meridiem; h, hour; Med, median; min, minute; PM, post meridiem; and PPV, positive predictive value.