Heart Rate as a Predictor of Mortality in Heart Failure Patients at the Time of Discharge from the Intensive Care Unit

Objective Heart rate serves as a critical prognostic factor in heart failure patients. We hypothesize that elevated heart rate in critically ill heart failure patients upon discharge from the intensive care unit (ICU) could be linked to adverse outcomes. Design We implemented a retrospective cohort study using data collected between 2008 and 2019 from the Medical Information Mart for Intensive Care IV (MIMIC-IV version 2.0) database. We examined the association between the last heart rate prior to ICU discharge and in-hospital mortality, total mortality, and ICU readmission. Setting ICU at Beth Israel Deaconess Medical Center Patients Adult patients admitted to the ICU diagnosed with heart failure. Interventions None Measurements and Main Results From the 76,943 ICU stays, we enrolled 2,365 patients in this study. We observed correlations between in-hospital mortality and ICU discharge heart rate of 83.56±15.81 bpm (survivors) vs. 93.84±17.28 bpm (nonsurvivors, p<0.001). Total mortality showed similar trends, with 83.67±15.36 bpm (survivors) vs. 85.23±17.25 bpm (nonsurvivors, p=0.027), as did ICU readmissions at 83.55±15.77 bpm (nonreadmitted) vs. 88.64±17.49 bpm (readmitted, p<0.001). Given multivariate analysis, the ICU discharge heart rate strongly predicted in-hospital mortality (OR 1.035 [95% CI 1.024-1.046], p < 0.001), total mortality (OR 1.007 [95% CI 1.001-1.014], p = 0.027) and ICU readmission (OR 1.015 [95% CI 1.007-1.023], p < 0.001). Patients with an ICU discharge heart rate >90 bpm demonstrated significantly higher in-hospital mortality (OR 2.986 [95% CI 2.066-4.315], p < 0.001), total mortality (OR 1.341 [95% CI 1.083-1.661], p = 0.007), and ICU readmission rates (OR 1.638 [95% CI 1.270-2.114], p < 0.001). Conclusions The findings suggest that heart failure patients with an elevated heart rate (>90 bpm) at ICU discharge are more likely to experience increased in-hospital mortality, total mortality, and ICU readmissions, indicating potential negative outcomes. Key Points Question: Does an elevated heart rate at ICU discharge increase in-hospital mortality, total mortality, and ICU readmission? Findings: This retrospective cohort study using the Medical Information Mart for Intensive Care IV database showed that a higher ICU discharge heart rate >90 bpm is a strong predictor of increased in-hospital mortality (OR 2.986, p < 0.001), total mortality (OR 1.341, p = 0.007), and ICU readmission (OR 1.638, p < 0.001). Meaning: Heart failure patients with an elevated heart rate (>90bpm) at ICU discharge are more likely to face increased risks of in-hospital mortality, total mortality, and ICU readmissions. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study used (or will use) ONLY openly available human data that were originally located at: https://physionet.org/content/mimic4wdb/0.1.0/ I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors