RESUMO
INTRODUCTION: This study aimed to evaluate the effects of dialysis on change of QT interval in pre-dialysis, 1 h after dialysis initiation, and post-dialysis period in patients on maintenance dialysis (MHD). METHODS: An observational prospective study was conducted, including 61 patients, on thrice-weekly MHD ≥3 months, and without acute diseases, at the Nephrology-Dialysis Department of a tertiary hospital in Vietnam. The exclusive criteria were atrial fibrillation, atrial flutter, branch block, prolonged QT recorded in medical history, and taking antiarrhythmic drugs lengthening QT interval before entering the study. Twelve-lead electrocardiographs and blood chemistries were done simultaneously before, 1 h after initiation, and after the dialysis session. RESULTS: The proportion of patients with prolonged QT interval increased significantly from 44.3% in pre-dialysis to 77% 1 h after dialysis initiation and 86.9% in post-dialysis session. Immediately after dialysis, the QT and QTc intervals on all 12 leads were significantly longer. Post-dialysis levels of potassium, chloride, magnesium, and urea decreased significantly from 3.97 (0.7), 98.6 (4.7), 1.04 (0.2), and 21.4 (6.1) to 2.78 (0.4), 96.6 (2.5), 0.87 (0.2), and 6.33 (2.8) mmol/L, respectively, whereas the calcium increased significantly from 2.19 (0.2) to 2.57 (0.2) mmol/L. There were significant differences in the potassium level at the dialysis initiation and its speed of reduction between the group without and with prolonged QT interval. CONCLUSIONS: There was an increased risk of prolonged QT interval in MHD patients regardless of the absence of the previous abnormal QT interval. Notably, this risk increased rapidly 1 h after the initiation of dialysis.