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. Setting Controlled cross-sectional study in a tertiary- care setting. Patients 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. Interventions 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 μV, 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). Conclusion 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.

QT interval dispersion in dialysis patients

“…The prolongation of QT dispersion in dialysis patients did not relate to gender, age, duration of dialysis, pH values, Kt/V or the serum levels of electrolytes. 10,25,26 A correlation with the left ventricular mass index was observed in HD patients, 5 but not in PD patients. 5,10 A prolonged QT dispersion is usually associated with an increased sympathetic drive, 18 but the association was not confirmed in ESRD patients.…”

“…Patients with chronic renal failure had a greater QTc interval and QTc dispersion compared with the control subjects. 5,23 High rates of QT dispersion have been observed in patients who receive continuous ambulatory peritoneal dialysis (CAPD). 10,23 It has been reported that a single session of HD might further increase QTc dispersion in both adults and children with chronic HD.…”

“…Large amount of or rapid potassium removal 29 Low calcium dialysate 5,30,37 Intracellular magnesium overload 31 Iron overload in CAPD patients 10 Rapid bicarbonate gain 4…”

“…However, serum levels of electrolytes in dialysis patients might have been within normal limits despite the patient having died of sudden death or fatal arrhythmia. 4,5 A reliable test to predict subjects at risk of ventricular arrhythmias would be an extremely useful tool for physicians taking care of dialysis patients. QT dispersion is defined as the difference between the longest and shortest QT intervals for a given set of complete 12 electrocardiogram (ECG) leads (QT dispersion = QTmax -QTmin).…”

Impact of haemodialysis on QTc dispersion in children

“…14,15 Many studies have reported that QT dispersion is prolonged in adults with chronic renal failure, particularly in the period immediately after the end of haemodialysis. [16][17][18][19][20][21][22][23][24] Very recently, corrected QT (QTc) dispersion has been demonstrated to be a useful marker for identifying dialysis patients at an increased risk for overall and cardiovascular mortality. 19 However, there are limited data regarding changes in QT interval and QT dispersion in the children receiving haemodialysis.…”