Post-dialysis heart rate variability predicted mortality in chronic hemodialysis patients

Abstract Background Autonomic disturbance is common in end stage renal disease (ESRD) and may be responsible for mortality in these patients. Heart rate variability (HRV) is the useful tool to assess for autonomic function. The predictive value of HRV on overall-mortality and proper timing of HRV measurement in chronic hemodialysis patients remain to be determined. Propose To evaluate the predictive value of HRV on all-cause mortality and explore the proper timing of HRV assessment by performing repeated HRV measurements at different time points including before, during and after hemodialysis. Methods We enrolled ESRD on hemodialysis patients between April 2018 to December 2018. HRV measurements were recorded 10 minutes before hemodialysis, 4 hours during hemodialysis and 10 minutes after hemodialysis. Baseline characteristics, clinical parameters and all-cause mortality were recorded. Cox-proportional hazard regression was used for the analysis of the association between HRV parameters with all-cause mortality. Results There were 163 patients enrolled to the study. After a median follow up of 40.4 months, 37 (22.7%) patients were expired. From multivariable Cox proportional hazard regression, the post-dialysis HRV parameters including lower very low frequency (VLF) (hazard ratio [HR], 0.900; 95% confidence interval [CI], 0.850–0.953; p<0.001), lower normalized low frequency (nLF) (HR, 0.954; 95% CI, 0.922–0.987; p=0.007), lower LF/HF ratio (HR, 0.268; 95% CI, 0.103–0.699; p=0.007) and higher normalized high frequency (nHF) (HR, 1.047; 95% CI, 1.012–1.083; p=0.007) were the independent predictors for all-cause mortality. HRV parameters at pre-dialysis and during dialysis were not associated with all-cause mortality. Patients with post-dialysis LF/HF ratio lower than the median value (<1.1) had a significantly higher all-cause mortality (log rank p=0.006) (Figure 1). Conclusion Post-dialysis period could be the most appropriate timing for HRV measurement. The HRV parameters at post-dialysis including lower VLF, lower nLF, higher nHF and lower LF/HF ratio were the independent predictors for all-cause mortality in chronic hemodialysis patients. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Faculty of Medicine endowment fund for medical research, Chiang Mai University, Thailand