Initial Reference Values of Electrocardiographic Alternans by Enhanced Adaptive Matched Filter

Electrocardiographic alternans (ECGA) is the ABAB fluctuation of the electrocardiogram (ECG) and may manifest as P-wave/QRS-complex/T-wave alternans (PWA/QRSA/TWA). ECGA is a cardiovascular risk index, and its characterization may depend on the automatic identification method. Normal ranges (needed to define risk conditions) are still not available for the new enhanced adaptive matched filter (EAMF) method. Thus, the present study aims to provide them. EAMF was used to characterize ECGA (in terms of: amplitude, $\mu V;$ area, $\mu V\times ms$; and duration, number of beats) in 15-lead ECG from 52 healthy subjects (39/13 male/female), from the “PTB Diagnostic ECG Database”. Median ECGA values over leads and subjects were: $2\ \mu V, 200\ \mu V\times ms$, and 17 beats for PWA; $1\ \mu V, 80\ \mu V\times ms$, and 8 beats for QRSA; and $7\ \mu V, {1300}\ \mu V\times ms$, and 49 beats for TWA. ECGA in females $(PWA:4\ \mu V, 350\ \mu V\times ms$ ,and 22 beats; QRSA: 1 $\mu V, 80\ \mu V \times ms$, and 11 beats; TWA: $10\ \mu V; 2000\ \mu V\times ms$, and 49 beats) was higher $(^{*}p < 0.05)$ than ECGA in males (PWA: $20\ \mu V^{*}, 200\ \mu V\times ms^{*}$, and $16\ beats^{*}$; QRSA: $1\ \mu V, 80\ \mu V\times ms$, and 7 beats; TWA: $6\mu V, 1150\ \mu V\times ms$, and 48 beats). Maximum ECGA values were observed in fundamental leads. The observed reference ECGA values seem reliable if comparing with pathological populations but are initial and analysis of wider datasets is needed.