title: The clinical significance of hyperkalaemia-associated repolarization abnormalities in end-stage renal disease.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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).
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: University of Manchester, Manchester Academic Health Sciences Centre, Manchester, UK. darrengreen@doctors.org.uk
authors.forename: Darren
authors.initials: D
authors.lastname: Green
authors.forename: Heather D
authors.initials: HD
authors.lastname: Green
authors.forename: David I
authors.initials: DI
authors.lastname: New
authors.forename: Philip A
authors.initials: PA
authors.lastname: Kalra
mesh_terms: D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000401:mortality; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006947:Hyperkalemia / Q000150:complications* / Q000175:diagnosis; D007676:Kidney Failure, Chronic / Q000150:complications / Q000401:mortality / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood*; D006435:Renal Dialysis; D016019:Survival Analysis
chemical_list: D011188:Potassium