Association of QRS-T angle and heart rate variability with major cardiac events and mortality in hemodialysis patients

Introduction Mortality in hemodialysis (HD) patients is high with significant proportion attributed to fatal arrhythmias. In a pilot study, we showed that intradialytic electrocardiographic (ECG) monitoring can yield stable profiles of selected repolarisation descriptors and heart rate variability (HRV) parameters. This study investigated the relationship of these ECG markers with major adverse cardiac events (MACE) and mortality. Methods Results Continuous ECGs were obtained during HD and repeated five times at 2-week intervals. The QRS-T angle calculated as Total Cosine R to T (TCRT) and T-wave morphology dispersion (TMD) were calculated in overlapping 10 s ECG segments. High- (HF) and low (LF)-frequency components and the LF/HF ratio of HRV were calculated every 5 min. These indices were averaged during the first hour of dialysis and subsequently overall recordings in each subject. All ECG parameters were available in 72 patients aged 61 +/- 15, 23 (31.9%) females and 26 (36.1%) diabetics. After a median follow up of 54.8 months, 16 patients died, 20 were transplanted, and 9 suffered MACE. TCRT (in degrees) was higher and LF/HF was lower in patients who died compared to survivors (112 +/- 30 vs. 73 +/- 35, p = 0.000 and 0.222 +/- 0.418 vs. 0.401 +/- 0.274, p = 0.000, respectively) and in MACE positive compared to negative (117 +/- 40 vs. 77 +/- 34, p = 0.017 and 0.125 +/- 0.333 vs.0.401 +/- 0.274, p = 0.007 respectively). In multivariate Cox regression analysis of mortality risk adjusted for age, diabetes mellitus, and coronary artery disease, TCRT and LF/HF remained significant predictors (p < 0.05). Conclusion QRS-T angle and HRV may serve risk assessment in future prospective studies in HD patients.