Heart rate is associated with mortality in patients undergoing continuous renal replacement therapy

BACKGROUND: Heart rate (HR) is an essential vital sign based on the finding that HR beyond its normal range is associated with several conditions or diseases, including high mortality in several clinical settings. Nevertheless, the clinical implications of HR remain unresolved in patients undergoing continuous renal replacement therapy (CRRT). METHODS: This retrospective cohort study included 828 patients who underwent CRRT due to acute kidney injury between 2010 and 2014. HR and other baseline parameters at the time of CRRT initiation were retrieved. The odds ratio (OR) of 30-day mortality was calculated using a multivariate logistic model. RESULTS: CRRT significantly lowered the HR of patients such that the pre- and post-CRRT HRs (average 6 hours) were 107 beats/min and 103 beats/min, respectively (P < 0.001). When we explored the relationship with 30-day mortality, only HR at the time of CRRT initiation, but not pre- or post-CRRT HR, had a significant relationship with mortality outcome. Based on this result, we divided patients into quartiles of HR at the time of CRRT initiation. Mortality OR in the 4th quartile HR group was 2.6 (1.78–3.92) compared with the 1st quartile HR group. This relationship remained consistent despite adjusting for 28 baseline covariates: OR, 1.7 (1.09–2.76); P = 0.020. However, HR was not associated with the weaning rate from CRRT. CONCLUSION: High HR at the time of CRRT initiation is subsequently related with high mortality. These results can be a basis for a future predictive model of CRRT-related mortality.