Effects and outcome of haemodialysis on QT intervals and QT dispersion in patients with chronic kidney disease.

Cardiovascular complications and sudden cardiac death are common in patients with chronic kidney disease and those on haemodialysis. This is often associated with prolonged QT(c) and QT(c) dispersion intervals. Forty-two patients on haemodialysis were compared with 45 control subjects to study the effect of haemodialysis on these ECG parameters and to compare mortality rates of those with excessively prolonged QT(c) and QT(c) dispersion. Maximum QT(cd), QT(d) and QT(c) dispersion increased with dialysis although these did not reach statistical significance. The maximum QT(c) was longer than 440 ms in 71.4% of patients post-dialysis, with a mortality rate of 73.3%. This was not statistically different from a mortality of 66.7% for those patients with maximum QT(c) less than 440 ms. Some (40.4%) of the patients had a QT(c) dispersion longer than 80 ms; the mortality rate of these (70.5%) was not statistically different from 68.0% for those with shorter QT(c) dispersion. Arrhythmia was rare in all cases. Patients with left ventricular hypertrophy (LVH) had the longest QT(c) dispersion and a statistically higher mortality rate. The in-hospital mortality in our patients was high (69.0%) but this might have been related to late presentation and limited facilities and not necessarily to acute cardiovascular complications of prolonged QT(c) dispersion.