QT dispersion before and after hemodialysis

Sudden cardiac death is common in patients on hemodialysis, and may occur in the immediate postdialysis period, when ventricular premature complexes are common. Elevated QT dispersion (Maximum - Minimum QT interval on standard 12-lead electrocardiogram) is associated with increased risk of ventricular arrhythmias following myocardial infarction, but has not previously been assessed in patients with chronic renal failure. We studied electrocardiograms recorded in 50 patients before and after a single hemodialysis session, and in 20 control subjects. QT dispersion was significantly higher in patients (63.1 +/- 20.6 ms) compared with control subjects (36.0 +/- 13.7 ms; P < 0.001) and rose significantly after hemodialysis to levels comparable to those seen following myocardial infarction (76.6 +/- 27.0 ms; P < 0.01). Because QT dispersion reflects nonhomogeneous recovery of ventricular excitability, hemodialysis patients may be at significantly greater risk of reentrant arrhythmias and sudden death in the postdialysis period.