Effect of haemodialysis on signal-averaged electrocardiogram P-wave parameters.

BACKGROUND The P-wave signal-averaged electrocardiogram (SAECG) is a non-invasive technique considered to indicate an increased risk for paroxysmal atrial fibrillation. The study was designed to evaluate the effect of the haemodialysis (HD) process on SAECG parameters in the group of selected HD patients. METHODS Forty-seven HD patients (without relevant cardiac diseases) were included. SAECGs were performed pre- and post-dialysis together with evaluating extracellular body water (ECW) by using bioimpedance and biochemical measurements. For each SAECG, filtered P-wave duration (FPD) and root mean square voltage of the final 20 ms of filtered P-wave (RMS20) were established. RESULTS The duration of either pre- or post-dialysis FDP was higher in HD patients than in the control group (P<0.001 and P = 0.005, respectively). The voltage of either pre- or post-dialysis RMS20 was reduced in HD patients compared with controls (P<0.001 in both cases). HD induced a decrease in the duration of the FDP and a significant increase in the voltage of RMS20 (P<0.001 in both cases). Stepwise multiple regression identified independent predictors of pre- and post-dialysis FDP as: (1) age; (2) pre- and post-dialysis ECW/kg body weight, respectively and; (3) pre- and post-dialysis haemoglobin levels, respectively. In the case of RMS20, we did not find any independent predictors either pre- or post-dialysis. CONCLUSIONS Our study revealed that P-wave SAECG parameters are abnormal in a significant portion of HD patients and improved with HD process. We have also demonstrated that patients' age, volume status as well as the presence of anaemia are important factors influencing P-wave SAECG parameters in HD patients.