The impact of chronic hemodialysis on QT dispersion, corrected QT dispersion and maximum QT-dispersion

Introduction: Sudden cardiac death is common in patients on hemodialysis and may
occur in the immediate postdialysis period when ventricular premature complexes are
common. QT dispersion, reflecting hetovogelity in ventricle repolarization, has been used
for predicting patients with risk of malignant arrhythmia and sudden death. The purpose
of the study was to assess the effect of hemodialysis on QT dispersion (QTd), corrected
QT dispersion (QTcd) and maximum QTc (QTcMax) in chronic hemodialysis patients.
Methods: In this descriptive-analytic study, data of 48 patients (30 male and 18 female
patients with mean age, 43±16 yr) on chronic hemodialysis were studied. 12 lead ECG
were recorded 5-10 minutes before and after hemodialysis in a standard setting and Na+,
K+, Ca++, Po4 and Mg++ levels were also determined pre and post hemodialysis.
During hemodialysis, no drug therapy was used except isotonic and hypertonic NaCl
influsions and sodium heparin. The maintenance drug therapy including digitalis,
antihypertensive, antianginal, and beta blocking agents was not changed. The data were
analyzed using SPSS software.
Results: The maximal QTd interval changed significantly from 434±12.8 ms to 443±21.33
ms (P<0.001). The QTd increased significantly from 55.87±7.5 ms to 61.27±9.09 ms
(P<0.001) and QTcd from 61.18±7.43ms to 68.79±10.32ms (P<0.001). 33.33% of the
patients before and 47.90% after hemodialysis had QTcMax more than 440 ms.
Conclusion: Hemodialysis increases the QTd, QTcd and QTcMax in patients with end-stage
renal failure. Thus it is likely that heterogeneity of regional ventricular repolarization increases
during hemodialysis.