Table 4.

Summary of intelligent ML-based SAA using augmented signals

Refs., Year	Database	Signal for FE, Segment length	Method description	ICF	FS	FV	Limitation	Key Findings
[44], 2017	CUDB, VFDB	ECG segment, NSH signal using MVMD, 8 s	Reconstruction of NSH signal using MVMD.	54	GA and SFFS using 3 ML classifiers and fivefolds CV.	Fivefolds CV	Limited database.	FFC of 20 features with SVM.
			Use of both stand-alone ECG and NSH signals for FE.				Time-comsuming for FS.	Effective twolayered FS.
			The two-layered FS with 3 ML classifiers to select 3 CFCs.					NSH signal using MVMD.
			Validation of CFCs and a combination of all ICFs using 5-folds CV.					Expansion of new ICFs.
[45], 2018	CUDB	ECG segment, (ECG segment)${}^2$ using Stationary wavelet transform, 4.1 s	Calculation of sample entropy for 10 selected bands using Stationary wavelet transform.	24	Bandwidth ranking with score	NA	Limited database.	Short segment.
			Bands ranked by NT-score which is a combination of relief, gain ratio, and fisher score.				No validation.	Expansion of ICFs from ECG segment and square of ECG segment.
			Performance of 3 ML classifiers for VFVT/non-VFVT and VF/non-VF scenarios.				Limited number of ICFs