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Signal-averaged ECG abnormalities in haemodialysis patients. Role of dialysis
M A Morales1, C Gremigni, P Dattolo
1CNR Clinical Physiology Institute, Florence, Italy.
Insights
Late potentials (LP) were found in 25% of end-stage renal failure (ESRF) patients, indicating increased risk for arrhythmias. Haemodialysis significantly prolonged filtered QRS duration, linked to potassium reduction.
Area of Science:
- Cardiology
- Nephrology
- Electrophysiology
Background:
- Late potentials (LP) on signal-averaged electrocardiogram (SAECG) predict malignant ventricular arrhythmias and sudden cardiac death in cardiomyopathy patients.
- End-stage renal failure (ESRF) patients frequently exhibit cardiac dysfunction and arrhythmias.
- The study aimed to determine LP prevalence and haemodialysis effects on SAECG in ESRF patients.
Purpose of the Study:
- To assess the prevalence of late potentials (LP) in end-stage renal failure (ESRF) patients.
- To evaluate the impact of haemodialysis on signal-averaged electrocardiogram (SAECG) parameters in ESRF patients.
Main Methods:
- Signal-averaged electrocardiogram (SAECG) recorded before and after haemodialysis in 45 ESRF patients.
- LP defined by QRS duration, LAS40, and RMS40 criteria.
- Serum electrolytes and echocardiography were analyzed.
Main Results:
- Late potentials (LP) were detected in 25% of patients (12/45), often associated with prior myocardial infarction or coronary artery disease (CAD).
- Patients with LP showed significantly greater wall motion score index.
- Haemodialysis led to significant prolongation of filtered QRS duration (fQRS), inversely related to serum potassium reduction.
Conclusions:
- A significant proportion of dialysis patients exhibit late potentials (LP), likely due to underlying coronary artery disease (CAD) and left ventricular dysfunction.
- The observed prolongation of filtered QRS duration (fQRS) after dialysis may be attributed to acute reductions in serum potassium levels.
Background:
Late potentials (LP) on the signal-averaged electrocardiogram (SAECG) are predictive of malignant ventricular arrhythmias and sudden cardiac death in patients with ischaemic and non-ischaemic cardiomyopathy. Cardiac dysfunction, both regional and global, as well as supraventricular and ventricular arrhythmias are reported in a high percentage of patients with end-stage renal failure (ESRF). The aim of the study was to assess the prevalence of LP and the effects of haemodialysis on the SAECG of ESRF patients.
Methods:
SAECG was recorded immediately before and within 30 min after the end of dialysis in 48 patients in sinus rhythm, free of conduction disturbances on ECG and of signs of congestive heart failure. Serum electrolytes were sampled together with the SAECG recordings. An echo-Doppler exam was performed within 2 weeks of the study. SAECGs were adequate for analysis in 45/48 patients. LP were present when at least two of the following criteria were fulfilled: QRS duration < or = 115 ms, LAS40 < or = 38 ms, RMS40 > or = 38 microV at 40 Hz high pass bidirectional filter, and noise <0.7 microV.
Results:
LP were detected in 12/45 patients (25%) on the SAECG before dialysis; of these 12 patients, seven had a history of a previous myocardial infarction and two had documented coronary artery disease (CAD). A significant greater wall motion score index--calculated on a 16 segment model--was reported in patients with LP (1.20+/-0.20 vs 1.01+/-0.03, P<0.01), while left ventricular mass was comparable in the two groups of patients. At the end of dialysis, a significant prolongation of fQRS duration was found both at 25 and 40 Hz filters (from 98+/-11 to 106+/-16 ms and from 97+/-12 s to 102+/-13 ms, respectively, P<0.001). A significant inverse relationship was seen between the percentage of dialysis-induced serum potassium reduction and fQRS changes at 40 Hz (r=-0.68, P<0.001).
Conclusions:
LP were detected in a significant proportion of dialysis patients, probably related to underlying CAD with left ventricular dysfunction. Prolongation of fQRS after dialysis could be explained by the acute reduction in serum potassium levels.