# Automatic Atrial Fibrillation Arrhythmia Detection Using Univariate and Multivariate Data
## 3 AF Arrhythmia Detection Methods
### Summary of RR-Based Automated AF Detection Research Studies
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Year [Ref]** & **Main Features** & **Techniques and Algorithms Used** & **Datasets** & **Best \%** & **Limitations and PERFORMANCE** & **Remarks** \\ \hline \multirow{4}{*}{2008 [51, 52]} & Subcutaneous R-wave and 2-min HRV RR Lorenz (_Poincare_) & Representation of RR Lorenz plots & & Se = 90.6 & In vivo study with low Pr\({}_{\text{r}}\) \\  & (_Poincare_) & Lorenz plots & Local & Se = 98.1 & Performance limited in AF \(<\) 2 min episodes \\  & geometric features & & & Pr = 55.1 (mean) & \\ \hline \multirow{4}{*}{2009 [41]} & RR RMSSD, & & & Se = 90.2 & \\  & RTBMSD, & & MITDB, & MITDB; & Techniques applied to 128-RR segments with \\  & Entropy & & AFDB & Se = 95.1 & 50\% AF ratios \\  & & & & (AFDB) & \\ \hline \multirow{4}{*}{2009 [32]} & RR Takens phase space, & Basic statistics and & & & \\  & k\({}_{\text{e}}\) slope of probability & Takens embedding for & & Se = 97.8 & Results achieved for time series as short as 4 QRRs \\  & density function of nonlinear attractor distance & & & & \\  & & & & \\ \hline \multirow{4}{*}{2011 [45]} & 100-AR distance difference (dRDDC) with & & & Se = 96.1 & Observed limitations in short AF episodes \\  & AF event & & Kolmogorov–Smirnov test & NSRDB & (AFDB) & (4–62 beats) \\  & stop, none & & & & \\ \hline \multirow{4}{*}{2011 [25]} & Sample entropy, quadratic & Basic statistics, logistic & MITDB (training), & Se = 91 & \\  & sample entropy (QSE, ad hoc) and RR variability for & regression, Wild-v2 statistic & UVA Virginia & Sp = 98 & \\  & template matching & & & Holter (local) & Pr = 63 & \\ \hline \multirow{4}{*}{2011 [27]} & Geometrical nonlinear & & & & \\  & features of RR vs. dRR & Representation of & NSRDB, & Se = 95.9 & 32-beat AF episodes; \\  & difference maps (with & recurrence plots & AFDB, & Sp = 95.4 & Different window size resolutions \\  & different resolutions) & & NSR2 DB & (combined DBs) & studied (32/64/128) \\ \hline \multirow{4}{*}{2011 [48]} & Time-varying coherence & Time-varying & & Se = 97.41 & \\  & using ARMA and & & transfer functions & AFDB, NSRDB & Sp = 97.54 & Applied to adjacent \\  & Shannon Entropy & & & Ac = 97.49 & 128-RR sets \\ \hline \multirow{4}{*}{2011 [31]} & RR 3-point median and & & & & \\  & specific decision thresholds & & signal fusion & & \\  & (Se = Sp) & & & \\ \hline \multirow{4}{*}{2011 [38]} & Vector angular index (VAI), & & & & \\  & vector length index (VLI), & Statistics (with & & Se = 98.3 & \\  & SD1 and SD2 & Mann–Whitney test) and & AFFermDB & Sp = 100 & \\  & geometric features of & 1-min RR & recurrence plot & & (SDI and VAI) & \\  & recurrence plots & & & \\ \hline \multirow{4}{*}{2011 [42]} & AF index derived from & & MITDB & & Method applied to 120 s \\  & histogram geometric & & (index setup), & Se = 92.9 & RR series; \\  & features (width, height ratio, peak) and premature & & Local & Sp = 90.9 & Limitation on \\  & beat presence & & (testing) & & \\ \hline \multirow{4}{*}{2012 [24]} & RR Coefficient of variation & & & & \\  & (CV), mean successive & & 2 Local DBs (2130 & Se \(>\) 94 & RR time interval \\  & difference and & & 10-s ECG samples) & Sp \(\approx\) 93 & only approach \\  & COSEn & & & & \\ \hline \multirow{4}{*}{2013 [47, 49]} & RR RMSSD, Shannon & & & & \\  & entropy, & Cubic spline (interpolation) & & & \\  & SampEn, RMSSD/\(<\)RR- & and decision logic & AFDB, NSRDB & Se = 97.26 & Method developed for \\  & (64 RR sets) & & & & \\ \hline \multirow{4}{*}{2014 [26]} & Modified Lorenz dRR, & & & & \\  & RR RMSSD, Shannon & Statistical methods and & MITDB, & Se = 95.79 & High performances \\  & entropy, & representation of dRR & AFDB, & Sp = 95.26 & achieved across \\  & turning point ratio and & recurrence plots & Long-Term AF & (MITDB for dRR) & different single features \\  & SampEn & & & \\ \hline \multirow{4}{*}{2014 [39]} & Three-pass: & Low/high scale reference & Long-Term AF, & Se = 96.89 & False negative detection \\  & Median + low-pass filters, & sequence generation and & ATDB & Sp = 98.25 & foreseen for short AF \\  & symbolic dynamics and & statistics on & (testing) & (AFDB) & episodes \\  & Shannon entropy & successive differences & & & \\ \hline \multirow{4}{*}{2015 [40]} & Symbolic dynamics and & & Long-Term AF & Se = 97.37 & Adapted thresholds and \\  & Shannon entropy with & & (training), AFDB, & Sp = 98.44 & test generalization to \\  & adapted thresholds & & MITDB, NSRDB & (AFDB) & other DBs \\ \hline \hline \end{tabular}
\end{table}