The impact of heart rate circadian rhythm on in-hospital mortality in patients with stroke and critically ill: Insights from the eICU Collaborative Research Database

Background: Data showing the impact of dysregulated heart rate circadian rhythm in patients with stroke and critically ill are scarce.

Objective: The purpose of this study was to investigate whether the circadian rhythm of heart rate was an independent risk factor for in-hospital mortality in patients with stroke and critically ill.

Methods: Study patients from the recorded eICU Collaborative Research Database were included in the present analyses. Three variables-mesor, amplitude, and peak time-were used to evaluate the heart rate circadian rhythm. The incremental value of circadian rhythm variables in addition to Acute Physiology and Chronic Health Evaluation (APACHE) IV score to predict in-hospital mortality was explored.

Results: A total of 6201 patients whose heart rate have cosinor rhythmicity. After adjustments, mesor per 10 beats/min increase was associated with a 1.18-fold (95% confidence interval [CI] 1.12- to 1.25-fold; P < .001) and amplitude per 5 beats/min was associated with a 1.17-fold (95% CI 1.07- to 1.27-fold; P < .001) increase in the risk of in-hospital mortality. The risk of in-hospital mortality was highest in patients who had peak time reached between 12:00 and 18:00 (odds ratio 1.35; 95% CI 1.06-1.72; P = .015). Compared with APACHE IV score only (c-index 0.757), a combination of APACHE IV score and circadian rhythm variables of heart rate (c-index 0.766) was associated with increased discriminative ability (P = .003).

Conclusion: Circadian rhythm of heart rate is an independent risk factor for in-hospital mortality in patients with stroke and critically ill. Including circadian rhythm variables of heart rate might increase the discriminative ability of the risk score to predict the prognosis of patients.