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Weighted Time Warping T-Wave Analysis Robust to Delineation Errors: Clinical Implications

Abstract:

T-wave (TW) morphology has been extensively investigated to develop specific risk pbkp_rediction markers like d{w} quantifying the level of warping needed to temporally align a TW respect to a reference one. However, TW boundaries delineation errors may jeopardise d{w} diagnostic power. Hence, we proposed two TW-based weighting function (WFs) obtained from (i) the reference TW (mathcal{T}), and (ii) the absolute value of its first-derivative (mathcal{D}). We, first, simulated TW boundaries delineation errors by shortening and widening two TWs with morphological variability. We, then, used the variation ratio (mathcal{R}) to compare d{w} derived applying the two WFs with that obtained in the control case (no weighting, mathcal{C}). Next, we compared the ability of d{w}, with and without WFs, in monitoring blood potassium concentration changes (Delta[K{+}]) by means of the Pear-son's correlation (r) in 29 48-hour Holter recordings from hemodyalisis (HD) patients. The simulations showed that mathcal{R} values for the two studied TWs, respectively, were 0.17 and 0.19 for mathcal{C}, 0.05 and 0.08 for mathcal{T} and 0.07 and 0.10 for mathcal{D}. However, similar r median [interquartile range] values were found for mathcal{C} (0.90 [0.27]), mathcal{T} (0.90 [0.25]) and mathcal{D} (0.90 [0.29]) in HD scenario. Thus, using WFs to compute d{w} reduces the effects of TW boundaries delineation errors, but no improvements in Delta[K{+}] monitoring in HD patients were observed. WFs impact on d{w} risk pbkp_rediction power remains to be studied