Objective: Most current algorithms for detecting Atrial Fibrillation (AF) rely on Heart Rate Variability (HRV), and only a few studies analyse the variability of Photopletysmography (PPG) waveform. This study aimed to compare morphological features of the PPG curve in patients with AF to those presenting a normal sinus rhythm (NSR) and evaluate their usefulness in AF detection.
Approach: 10-minute PPG signals were obtained from patients with persistent/paroxysmal AF and NSR. Nine morphological parameters (1/ΔT, Pulse Width [PW], Augmentation Index [AI], b/a, e/a, [b-e]/a, Crest Time [CT], Inflection Point Area [IPA], Area and five HRV parameters (Heart rate [HR], Shannon entropy [ShE], root mean square of the successive differences [RMSSD], number of pairs of consecutive systolic peaks [R-R] that differ by more than 50 ms [NN50], standard deviation of the R-R intervals [SDNN]) were calculated.
Main Results: Eighty subjects, including 33 with AF and 47 with NSR were recruited. In univariate analysis five morphological features (1/ΔT, p<0.001; b/a, p<0.001; [b-e]/a, p<0.001; CT, p=0.011 and Area, p<0.001) and all HRV parameters (p=0.01 for HR and p<0.001 for others) were significantly different between the study groups. In the stepwise multivariate model (Area under the curve [AUC] = 0.988 [0.974-1.000]), three morphological parameters (PW, p<0.001; e/a, p=0.011; (b-e)/a, p<0.001) and three of HRV parameters (ShE, p=0.01; NN50, p<0.001, HR, p = 0.01) were significant. 
Significance: There are significant differences between AF and NSR, PPG waveform, which are useful in AF detection algorithm. Moreover adding those features to HRV-based algorithms may improve their specificity and sensitivity.
