Abstract 6276: Nocturnal Reduced Heart Rate Variability Predicts Cardiovascular Morbidity and Mortality in Chronic Hemodialysis Patients
Heart rate variability (HRV) reflects cardiac autonomic function mainly parasympathetic activity, and reduced HRV has been reported to be an increased risk for death in various populations. On the other hand, autonomic dysfunction frequently are observed in hemodialysis patients who are at high risk for cardiovascular (CV) disease, however, its prognostic value in this population remains unknown. We investigated whether HRV predicts CV morbidity and mortality was studied in chronic hemodialysis patients. 309 outer patients on hemodialysis (male 55%, age 63±11years, duration of dialysis 6±6years, diabetes 46%) underwent 24hr ambulatory Holter ECG monitoring. From obtained normal-normal R-R interval (NN interval) time series, standard deviation of NN interval (SDNN) during sleeping period described on ambulatory recording by patients themselves were calculated. They were divided into tertiles according to nocturnal SDNN levels; <53ms (T1, n=103), 54ms–88ms (T2, n=103) and >89ms (T3, n=103). They were followed up for 5years. During follow-up period (54±11months), 156 CV events (51%) occurred and 64 patients (21%) died including 26 CV death. CV event-free survival rate for 5-year was 48%, 59% and 71% in the groups of T1, T2 and T3, respectively (p=0.0028). Hazard ratio (HR) was 1.71 [95% confidential interval (CI) 1.06 –2.79, p=0.029] for T2 vs. T3 and 2.24 (95%CI 1.40 –3.59, p=0.0008) for T1 vs. T3, respectively. CV Survival rate was 86%, 92% and 97% (p=0.0021), and all-cause survival rate was 65%, 78% and 87% in the groups of T1, T2 and T3 (p=0.0001), respectively. Even after adjustment for gender, age, diabetes, hypertension, hyperlipidemia, smoking, history of CV disease, hemoglobin, albumin and C-reactive protein, reduced SDNN was an independent predictor for CV events (HR 2.03, 95% CI 1.18 –3.48, p=0.010 for T1 vs. T3], for CV mortality (HR 7.20, 95%CI 1.42–36.51, p=0.0003 for T1 vs. T3) and for all-cause mortality (HR 3.52, 95%CI 1.78 – 6.98, p=0.014 for T1 vs. T3), respectively. These data suggests that nocturnal reduced HRV is a significant predictor of CV morbidity and mortality in hemodialysis patients, thus, screening of HRV using Holter monitoring might be useful for assessment of CV risk stratification.