Effect of Hemodialysis on Corrected QT Interval and QTc Dispersion.

Hemodialysis patients are at higher risk of cardiovascular disease due to traditional and dialysis-related risk factors. Our aim was to study the effects of hemodialysis on the corrected QT interval (QTc) and QTc dispersion in chronic kidney disease (CKD) without clinically manifest heart disease. Two hundred cases of CKD on chronic intermittent hemodialysis of >3 months' duration were included in the study. Twelve-lead electrocardiography and samples for serum creatinine, potassium, calcium, and magnesium were taken before and after dialysis. The mean age of patients was 52.4 ± 17 years with male-to-female ratio of 3:1. QTc interval and QTc dispersion were prolonged in 47% and 59% before and 50% and 89% of patients after hemodialysis, respectively. The mean values of QTc were 433.4 ± 36.9 ms before and 451.4 ± 39.6 ms after hemodialysis ( p = 0.001) and the mean values of QTc dispersion were 60.5 ± 19.3 ms before and 81.5 ± 24.4 ms after hemodialysis ( p = 0.001). Similar pattern was observed in all etiological groups of CKD, except for QTc dispersion in malignancy-related CKD ( p = 0.216). After hemodialysis, there was a significant fall in the mean values of serum potassium ( p = 0.001), rise in serum calcium ( p = 0.001), and no change in magnesium ( p = 0.424). Patients with post hemodialysis QTc dispersion >74 ms had significantly low mean values of serum potassium and calcium as compared to <74 ms group. Large numbers of hemodialysis patients have a prolonged QTc interval and QTc dispersion with a significant increase in the mean values after hemodialysis. There is a significant fall in serum potassium and rise in serum calcium after dialysis.