Post-Ventricular Premature Contraction Phase Correction Improves the Predictive Value of Average T-wave Alternans in Ambulatory ECG Recordings

Objective: We proposed and evaluated a method for correcting possible phase-shifts provoked by the presence of ventricular premature contractions (VPCs) for a better assessment of T wave alternans (TWA). Methods: First, we synthesized ECG signals with artificial TWA in the presence of different noise sources. Then, we assessed the prognostic value for sudden cardiac death (SCD) of the long-term average of TWA amplitude, (the index of average alternans, IAA) in ambulatory ECG signals from congestive heart failure (CHF) and evaluated whether it is sensitive to the presence of VPCs. Results: The inclusion of the phase correction after VPC in the processing always improved estimation accuracy of the IAA under different noisy conditions and regardless of the number of the VPCs included in the sequence. It presented also a positive impact in the prognostic value of IAA with increased hazard ratios (from 17% to 29%, depending of the scenario) in comparison to the non-inclusion of this step. Conclusion: the proposed methodology for IAA estimation, which corrects for the possible phase reversal on TWA after the presence of VPCs, represents a robust TWA estimation approach with a significant impact in the prognostic value of IAA for SCD stratification in CHF patients. Significance: an accurate TWA estimation has a potential direct clinical impact in non-invasive SCD stratification, allowing better identification of patients at higher risk and helping clinicians in adopting the most appropriate therapeutic strategy.