Arrhythmia and Time of Day in Maintenance Hemodialysis: Secondary Analysis of the Monitoring in Dialysis Study

Rationale & Objective The incidence of arrhythmia varies by time of day. How this impacts individuals on maintenance dialysis is uncertain. Our objective was to quantify the relationship of arrhythmia with the time of day and the timing of dialysis. Study Design Secondary analysis of Monitoring in Dialysis study- a multicenter prospective cohort study. Settings & Participants Loop recorders were implanted for continuous cardiac monitoring in 66 participants on maintenance dialysis with a follow up of 6 months. Exposure Time of day based on 6-hour intervals Outcomes Event rates of clinically significant arrhythmia Analytical Approach Negative binomial mixed effects regression models for repeated measures were used to evaluate data from the Monitoring in Dialysis study for differences in diurnal patterns of clinically significant arrhythmia among those with end stage kidney disease with heart failure and end stage kidney disease alone. We additionally analyzed rates according to presence of heart failure, time of dialysis shift, and dialysis vs. non dialysis day. Results Rates of clinically significant arrhythmia peaked between 0:00 AM-<6:00 AM and were more than 1.5-fold as frequent during this interval compared with the rest of the day. In contrast, variations in atrial fibrillation peaked between 6:00 AM-<12: PM, but variations across the day were qualitatively small. Clinically significant arrhythmia occurred at numerically higher rate in individuals with end stage kidney disease and heart failure (5.9 events/month, 95% CI: 1.3-26.8) than those without heart failure (4.0 events/month, 95% CI: 0.9-17.9). Although differences in overall rate were not significant, their periodicity was significantly different (P<0.001) with a peak between 0:00 AM-6:00 AM with kidney failure alone and between 6:00 AM-<12:00 PM in those with heart failure. Although the overall clinically significant arrhythmia rate was similar with morning compared with evening dialysis shifts (P=0.43), their periodicity differed with a peak between 0:00 AM-<6:00 AM in those with AM dialysis and a later peak between 6:00 AM-<12:00 PM in those with PM shifts Limitations Post hoc analysis, unable to account for unmeasured confounders Conclusion Clinically significant arrhythmias showed strong diurnal patterns with a maximal peak between 0:00-<6:00 AM and noon. Although overall arrhythmia rates were similar the peak rate occurred overnight in individuals without heart failure and during the morning in individuals with heart failure. Further exploration of the influence of circadian rhythm on arrhythmia in the setting of hemodialysis is needed.