The clinical significance of hyperkalaemia-associated repolarization abnormalities in end-stage renal disease

• Published in: Nephrology, dialysis, transplantation dialysis, transplantation, 2013-01, Vol.28 (1), p.99-105
• Main Authors: Green, Darren, Green, Heather D, New, David I, Kalra, Philip A
• Format: Article
• Language: English
• Subjects: Adult; Aged; Arrhythmias, Cardiac - etiology; Arrhythmias, Cardiac - mortality; Electrocardiography; Female; Follow-Up Studies; Humans; Hyperkalemia - complications; Hyperkalemia - diagnosis; Kidney Failure, Chronic - complications; Kidney Failure, Chronic - mortality; Kidney Failure, Chronic - physiopathology; Male; Middle Aged; Potassium - blood; Renal Dialysis; Survival Analysis
• ISSN: 0931-0509; 1460-2385
• DOI: 10.1093/ndt/gfs129

Hyperkalaemia is a common potentially fatal complication of chronic kidney disease (CKD). It may manifest as electrocardiogram (ECG) changes, the earliest of which is T-wave 'tenting'. However, this occurs in less than half of episodes of hyperkalaemia. The aim of this study was to determine what other clinical features relate to the probability of T-wave tenting; and if there is a longer-term survival difference between patients who develop tenting and those who do not. One hundred and forty-five patients with end-stage renal disease who had standard 12-lead ECG and concurrent serum potassium measurement were enrolled. The presence of tenting and the ratio of the amplitude of the tallest precordial T-wave and R-wave were determined (T:R). Tenting was as common in normal range serum potassium as hyperkalaemia (33 versus 31%) and less common than in left ventricular hypertrophy (44%). T:R was less sensitive (24 versus 33%) but more specific (85 versus 67%) than tenting at correctly identifying hyperkalaemia ≥ 6.0 mmol/L. Tenting became less common with increasing age. Dialysis patients were more likely to show increased T:R that pre-dialysis Stage 5 CKD. Elevated T:R was not associated with worse cardiovascular outcome but was associated with increased risk of sudden death over a mean follow-up of 3.8 years (hazard ratio = 8.3, P = 0.021). The reason for the variability in T-wave changes is not clear. The ratio of precordial T-wave to R-wave amplitude is a more specific measure than tenting but both are poorly sensitive at detecting hyperkalaemia. The greater risk for sudden death may represent a susceptibility to cardiac arrhythmia during repolarization.