High prevalence of cardiac autonomic dysfunction and T-wave alternans in dialysis patients.

Background Chronic hemodialysis (HD) patients have an elevated risk of sudden cardiac death (SCD), particularly in the 24 hours before the first HD of the week. Temporal changes in cardiac autonomic dysfunction, as characterized by abnormalities in heart rate variability (HRV) and heart rate turbulence (HRT), along with T-wave alternans (TWA), may contribute to this dispersion of risk. Objective This study sought to determine the prevalence of abnormal HRV, HRT, and TWA in HD patients and to compare their temporal distribution among periods of variable SCD risk. Methods HRV, HRT, and TWA were analyzed from 72-hour Holter monitors in HD patients, and results were compared among the 24-hour high-risk period before the first dialysis session of the week, the 24-hour intermediate-risk period beginning with the weeks' first dialysis, and the low-risk period the day after the first dialysis. Positive cut points were standard deviation of all normal R-R intervals ≤70 ms for HRV, onset ≥0% and/or slope ≤2.5 ms/R-R for HRT, and ≥53 μV for TWA. Results Of 41 enrollees, 28 (46% male, age 55 ± 12, ejection fraction 57% ± 11%) had sufficient data for analysis. Abnormalities were prevalent with 82%, 75%, and 96% of patients reaching threshold for HRV, HRT, and TWA in at least one 24-hour period, respectively. There was no significant difference in the prevalence of abnormal measures among dialytic intervals nor in the intraindividual distribution of abnormal measures ( P >.05 for all). Conclusion Abnormal HRV, HRT, and TWA are prevalent in HD patients and may indicate heightened SCD risk. No significant correlation was observed among these measures and recognized periods of variable risk.