An Evaluation of Tp-e Interval and its Associations with Electrolyte Imbalances in the Electrocardiography of Elderly Patients on Hemodialysis

Aim: Sudden cardiac death (SCD) due to arrhythmias is a major cause of death in elderly patients on hemodialysis (HD). It has been found that prolonged Tp-e interval (Tpe) on electrocardiography (ECG) and increased Tpe/QTc ratio are strongly associated with SCD. In this study, we aimed to inves¬tigate the effects of changes in serum electrolyte levels on the pre- and post-HD ECG parameters, particularly Tpe. Methods: The study included 160 HD patients (with no disease or medication known to affect the QT interval) and 80 age- and sex-matched controls with normal kidney functions. All participants were aged 55 years or older. Pre- and post-HD serum electrolyte values and ECG re¬cordings were obtained. The heart rate, QRS interval, QTc, Tpe, and Tpe/QTc values were calculated. The pre-HD data were compared with the post-HD data as well as with controls. Results: The pre- and post-HD Tpe (p<0.001 for both comparisons) and Tpe/QTc (p=0.024 and p<0.001, respectively) values were significantly higher in the HD group than in the control group. The post-HD Tpe and Tpe/QTc values were significantly increased compared to the pre-HD values (p<0.001 for each comparison). The pre-HD Tpe was longer in patients with hypocalcemia or hy¬perphosphatemia than in normocalcemic and normophosphatemic patients (p=0.04 for both data¬sets). ΔTpe was significantly correlated with Δcalcium (r=-0.19, p=0.02) and Δphosphorus (r=-0.23, p=0.004). Conclusion: In the elderly patients on HD, Tpe, which was prolonged before HD, was even more prolonged after HD. Hypocalcemia and hyperphosphatemia may be among the un¬derlying factors.