Association of cardiac autonomic neuropathy assessed by heart rate response during exercise with intradialytic hypotension and mortality in hemodialysis patients

The heart rate (HR) reflects the dynamic behavior of the autonomic nervous system, and HR profiles during the exercise test provide prognostic information. However, there are no reports of these factors in hemodialysis patients. Data from 256 patients (mean 68.8 years old) who underwent an exercise test were statistically analyzed. Patients were evaluated for the percent HR reserve from HR at peak exercise, HR recovery for one minute after peak exercise, and exercise capacity, as well as intradialytic hypotension (IDH). The prevalence of chronotropic incompetence (96.1%), defined as under 80% HR reserve, and abnormal HR recovery (60.5%), defined as under 12 beats, were very common. Eighty-four deaths occurred during the follow-up period (median, 3.8 years). A slow HR recovery under 7 beats was associated with IDH after adjustment (odds ratio 2.7, 95% confidence interval 1.1-6.4). HR recovery under 12 beats (hazard ratio over study period 5.1, 95% confidence interval 2.5-10.5), HR reserve under 26.2% (3.4, 1.7-6.8), and IDH (1.7, 1.1-2.8) were associated with all-cause mortality after adjustment. Considering the confounding of all three variables, only HR recovery under 12 beats remained associated with the all-cause and cause-specific mortality ("cardiovascular" and "non-cardiovascular"). This association was consistent even in subgroup analyses based on the presence of diabetes and cardiovascular disease. Thus, HR profiles during the exercise can reflect potential health conditions related to cardiac autonomic neuropathy in hemodialysis patients that affect IDH and their survival.