Study of the Relationship between QTc Time Trends and Microglobulin during Hemodialysis

Background: Several studies have revealed a relationship between an abnormal QTc interval of electrocardiogram, mortality, and sudden death in patients undergoing hemodialysis (HD). However, only some studies have investigated the changes in the QTc interval during HD sessions and the determining factors. Therefore, our aim was to investigate the relationship between various parameters and QTc interval during HD. Methods: This cross-sectional study enrolled 53 patients undergoing maintenance HD. The QTc was measured hourly from HD initiation. Blood samples were collected at the beginning of each HD session. Blood Ca, Mg, K, and HCO3-levels were evaluated at the beginning, 2 h after, and at the end of the HD session. The relationship between changes in the QTc interval and various parameters was analyzed using Spearman’s correlation and multiple regression analyses. Results: The patients were aged 37–91 years (Mean, 66.9) years, and the dialysis duration was 1–402 months (median, 2 months). Of the patients, 39.6% were diagnosed with a prolonged QTc interval (≥460 ms) at HD initiation (median, 455 ms). The QTc interval was shortened by 11 ms at 2 h and then increased by 3 ms at the end. Peak changes in the QTc interval occurred 2 h after HD initiation. Thus, we estimated the factors that affected the change in QTc 2 h after dialysis initiation (ΔQTc2h). HD treatment duration (r = 0.312, P = 0.025) and serum levels of β2MG (r = 0.324, P = 0.019) were positively correlated with ΔQTc2h. The 2 h change in corrected Ca (ΔcCa2h) (r = -0.31, P = 0.03), intact PTH (r = -0.30, P = 0.035), and α2MG (r = -0.46, P = 0.001) were negatively correlated with ΔQTc2h. The association between β2MG and ΔQTc2h was evaluated separately in the high and low β2MG groups. β2MG significantly suppressed the decline in QTc interval in the high β2MG group (P = 0.03). According to the multiple regression analysis, β2MG (β = 0.389, P = 0.0027) and α2MG (β = -0.326, P = 0.020) were significant predictors of ΔQTc2h. Conclusion: The change in QTc time 2 h after dialysis initiation correlated significantly with β2MG and α2MG. The QTc time was expected to change proportionately to serum Ca; however, the QTc time was shortest after 2 h of dialysis. Removal of β2MG and α2MG by dialysis depends on HD treatment time, which may affect prolonged QTc interval in QTc 2 h after dialysis initiation.