Improvement of maximum corrected QT and corrected QT dispersion in electrocardiography after kidney transplantation

The electrocardiography (ECG) markers of corrected QT interval (QTc) and QTc dispersion are prolonged in patients on hemodialysis. This study was carried out to investigate if changes in these markers will reverse by successful kidney transplantation.

Twenty-six kidney allograft recipients with functioning grafts, 26 patients on maintenance hemodialysis, and 22 healthy individuals were underwent a 12-lead ECG and laboratory studies for electrolytes and arterial blood gas. In the patients on dialysis, ECG and laboratory studies were performed prior to the start of a hemodialysis session. Both QT dispersion and maximum QT were corrected for heart rate (QTc dispersion and maximum QTc). The results were compared between the three groups.

The mean QTc dispersion was 30.3 +/- 15.2 ms, 27.6 +/- 8.3 ms, and 24.5 +/- 9.0 ms, and the mean maximum QTc was 464.7 +/- 23.0 ms, 436.3 +/- 19.0 ms, and 415.0 +/- 85.0 ms in the patients on dialysis, transplant recipients, and controls, respectively. The QTc dispersion value was lower in the transplant group than in the hemodialysis group, but the differences were not statistically significant. Whereas, the maximum QTc was significantly shorter in the transplant recipients as compared with the patients on hemodialysis (P < .02). There was a significant correlation between the maximum QTc and serum calcium level (P < .001), serum magnesium level (P < .001), and pH (P < .001).

Prolonged maximum QTc decreases towards normal by successful kidney transplantation. These corrections are most likely due to normalization of electrolytes and the acid-base status from a uremic state to the normal kidney function.