TABLE 2. Criteria for QRSd Measurement Algorithm Steps.

Step	Action	Parameter	Value/Criteria
Prior to QRSd algorithm	Removal of array-specific outliers	Morphological features	Cross-correlation
			Peak polarities, magnitudes, and temporal position
		Exclusion criteria	Channel is morphologic outlier in the first, middle, and last PM complex
6.	Identification of peak bounds	Leading or trailing peak boundary	Earlier of zero-crossing and concavity change
	Significance assessment	Order of candidate peak evaluation	In order of ascending proximity to the reference peak
	Peak significance criteria	Peak position	Occurs after preceding significant peak bounds
		Peak amplitude	Opposite polarity of preceding significant peak
		Criteria scaling factor	Ratio of candidate peak height to reference peak height
		Leading and falling phase slope	Reference peak slope scaling factor
		Leading and falling phase curvature	Reference peak curvature scaling factor
7.	Removal of array-specific peak outliers	Maximum peak-to-peak spacing	52 ms A
8.	Delineation of channel specific borders	Amplitude	<50% of the height of the closest significant peak
		Slope	<2.5 −2 mV/ms B
9.	Delineation of array-specific borders	Group of normal array-specific border values	Largest group of borders within 20-ms
		Array-specific start	Earliest in the group of array-specific normal start values
		Array-specific end	Latest in the group of array-specific normal start values
10.	Delineation of global borders	Global start	Earlier of the array-specific start values
		Global end	Later of the array-specific end values

^ABased on precision of 12-lead ECG grid paper

^BBased on difference () between paired global and widest single-lead 12-lead ECG QRSd measurements (n = 150)

Criteria without sources were determined during the development process