Baseline Drifting Removal Affects Microvolt T-Wave Alternans Measurement

Microvolt T-Wave alternans (MTWA) is a beat-to-beat alternation of T-wave and is considered an early marker of sudden cardiac death.In clinical analysis, baseline drifting and other interferences are expected, requiring preprocessing, such as baseline drifting removal by spline functions.This work focuses on the impact of this approach on MTWA assessment for real-world signals.The classical approach estimates a baseline signal using ECG fiducial points and subtracts it from the original signal.In this preprocessed signal, the classical approach vector (CAV) is assembled using the maximum value of a T-wave search window.As an alternative, the T-wave amplitude vector (AAV) is assessed by the difference between the T-wave peak and end, avoiding baseline drifting removal.The spectral method is used to evaluate MTWA.The alternans spectrum from CAV and AAV were compared by coherence analysis using the Fisher transform.Alternans peak and ratio were compared using the Pearson coefficient and Ttest.The study at the alternation frequency showed statistically significant coherence between the AAV and CAV spectra (average 0.54).Both alternans peak and alternans ratio for AAV were higher than CAV, suggesting that AAV avoids CAV-induced artifacts that interfere with MTWA assessment and warrants further investigation.