Fig 1.
Examples of ECG found in public (top) and OHCA (bottom) data.
The top-left segment corresponds to a VF from CUDB (record, cu05) right after VF onset, and presents large amplitude and a fibrillation frequency of 4.5 Hz. The bottom-left segments were recorded during OHCA 5–10 minutes after VF onset, and have smaller amplitudes and fibrillation frequencies (3.5 Hz and 2.5 Hz). The top-right segment corresponds to a NSR from cu05 right before VF onset. The bottom-right segments are examples of PEA in OHCA patients. Both cases show aberrant QRS complexes and low heart rates. The bottom example presents an extremely low heart-rate of 15 beats per minute.
Fig 2.
Overview of the test procedure.
Blue boxes specify the figures and tables where the results corresponding to each procedure can be found in the manuscript.
Table 1.
Description of the datasets used for classification.
Table 2.
Performance analysis of single features for all datasets.
Fig 3.
Box plots of the performance metrics for the five algorithms for the public databases (a) and the OHCA database (b).
All features were included in the algorithms.
Fig 4.
Feature selection with BSTsel (top) and the L1-LRsel (bottom) approaches.
The results are shown for 4-s (left) and 8-s (right) segments for both public and OHCA databases. The mean BER is shown (with errorbars) for each subset size, and the horizontal line represents the subset selection threshold for the public (red) and OHCA (green) databases. The triangle and dot marks and their corresponding numbers represent the selected subset and the minimum BER subset, respectively.
Table 3.
Features selected with BSTsel and L1-LRsel ordered by decreasing relevance.
Table 4.
Processing times (ms) to compute the features when all features and optimal feature subsets are computed.
Table 5.
Decline in BER for the features selected using the L1-LR or BST algorithms.
Fig 5.
Examples of misclassified 8-s ECG samples from the public (left) and OHCA (right) databases.
A VF is shown on top and two nonshockable rhythms below for both databases.