title: QT dispersion and signal-averaged electrocardiogram in hemodialysis and CAPD patients.
abstract: OBJECTIVE
  The aim of this study was to compare QT dispersion (QTd) and signal-averaged electrocardiogram (SA-ECG) parameters that may predict risk of malignant arrhythmias in patients on hemodialysis (HD), on continuous ambulatory peritoneal dialysis (CAPD), and in controls.
  
  
  METHODS
  Controlled cross-sectional study in a tertiary-care setting.
  
  
  METHODS
  28 HD (M/F 18/10; mean age 32 +/- 9 years), 29 CAPD (M/F 17/12; mean age 34 +/- 10 years), and 29 healthy controls (M/F 17/12; mean age 32 +/- 8 years) were included.
  
  
  METHODS
  On ECG, minimum (QTmin) and maximum (QTmax) QT duration and their difference (QTd) were measured. In SA-ECG, duration of filtered QRS, HFLA signals less than 40 microV, and RMS voltage (40 ms) were also measured.
  
  
  RESULTS
  Higher serum Ca2+ and lower K+ levels were found in CAPD compared to HD. All QT parameters were increased in HD and CAPD compared to controls. QT dispersion was significantly prolonged in HD compared to CAPD. In HD, QTd was correlated with left ventricular (LV) mass index (r = 0.53, p = 0.004), but not in CAPD (r = -0.09, p = 0.63). QT dispersion was significantly prolonged in patients with LV hypertrophy compared to patients without hypertrophy on HD (68 +/- 18 ms vs 49 +/- 18 ms, p = 0.008). In the analysis of SA-ECG, 3 of the 28 (11%) HD and 2 of the 29 (7%) CAPD patients had abnormal late potentials. Patients on HD and CAPD had significantly higher filtered-QRS duration compared to controls (105 +/- 15 ms and 104 +/- 12 ms vs 95 +/- 5 ms, respectively, p = 0.04). Patients with LV hypertrophy had higher filtered-QRS duration compared to patients without hypertrophy (109 +/- 12 ms vs 95 +/- 8 ms, p < 0.001).
  
  
  CONCLUSIONS
  Dialysis patients had prolonged QTd and increased filtered-QRS duration in SA-ECG compared to controls. Patients on HD had longer QTd than patients on CAPD. QTd has been correlated to LV mass index in HD, but not in CAPD. This difference might be due to the effect of different dialysis modalities on electrolytes, especially the higher serum Ca2+ levels.
authors.affiliation: Department of Internal Medicine, Istanbul School of Medicine, Turkey. alaattiny@hotmail.com
authors.forename: A
authors.initials: A
authors.lastname: Yildiz
authors.forename: V
authors.initials: V
authors.lastname: Akkaya
authors.forename: S
authors.initials: S
authors.lastname: Sahin
authors.forename: T
authors.initials: T
authors.lastname: Tükek
authors.forename: M
authors.initials: M
authors.lastname: Besler
authors.forename: S
authors.initials: S
authors.lastname: Bozfakioglu
authors.forename: F
authors.initials: F
authors.lastname: Korkut
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000209:etiology; D002118:Calcium / Q000097:blood; D003430:Cross-Sectional Studies; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000209:etiology; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications / Q000628:therapy; D008297:Male; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000009:adverse effects; D011188:Potassium / Q000097:blood; D006435:Renal Dialysis / Q000009:adverse effects; D015203:Reproducibility of Results; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted
chemical_list: D011188:Potassium; D002118:Calcium