Hemodialysis-induced variability of the QRS-T spatial angle reveals distinct electrophysiological patterns in...

Cardiovascular mortality remains the leading cause of death among patients with end-stage renal disease (ESRD). The QRS-T spatial angle (QRSTsa), indicating ventricular electrical heterogeneity, has been shown to predict major adverse cardiac events and sudden cardiac death. However, evidence regarding the effect of a single haemodialysis (HD) session on QRSTsa is inconsistent.

Forty-three patients with ESRD undergoing maintenance HD were evaluated. Digital electrocardiography (ECG) and vectorcardiography (VCG) were recorded immediately before, halfway through, and after HD. The QRSTsa was calculated using the inverse Dower transformation method. Biochemical analyses, including oxidative stress biomarkers such as total oxidant status to total oxidant capacity ratio (TOS/TOC), total antioxidant status to total antioxidant capacity ratio (TAS/TAC), oxidised low-density lipoprotein (oxLDL), and malondialdehyde (MDA), were performed before and after HD. Patients were stratified according to changes in QRSTsa into increasing and decreasing/stable QRSTsa groups. Multivariable regression identified predictors of QRSTsa dynamics.

QRSTsa exhibited a biphasic response, significantly increasing during the first half of HD (p = 0.0342) and partially returning toward baseline by the end of treatment (p = 0.0415). QRSTsa increased in 40% of patients (Δ +17.77 ± 17.16°, p < 0.0001) and decreased or was stable in 60% (Δ -9.04 ± 24.36°, p = 0.0351). Patients with QRSTsa increase showed significantly higher elevations in oxLDL (p = 0.020) and TOS/TOC (p = 0.0378), and had lower baseline antioxidant reserve. Independent predictors of QRSTsa increase included baseline oxLDL, prolongation of the corrected QT interval (QTc) during late HD, and female sex (adjusted R² = 0.391, p = 0.0002). In an alternative regression model oxLDL can be replaced by TOS/TOC (adjusted R² = 0.322, p = 0.003).

Haemodialysis induces heterogeneous alterations in QRSTsa, identifying subgroups with differing electrophysiological responses. Increased QRSTsa was associated with greater oxidative stress burden, QTc prolongation, and female sex, suggesting higher arrhythmic vulnerability. QRSTsa may serve as a dynamic marker of intradialytic electrical instability. Larger studies are warranted to validate clinical utility and therapeutic implications.