Electrolyte Abnormalities and Clinical Outcomes in Heart Failure Patients: A Retrospective Cohort Study
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Abstract
ABSTRACT Background Electrolyte abnormalities commonly complicate heart failure management, yet their prognostic significance and optimal monitoring strategies remain incompletely characterized. We examined the prevalence, temporal patterns, and clinical outcomes associated with electrolyte abnormalities in hospitalized heart failure patients. Methods Retrospective cohort study of 30,678 heart failure patients (80,408 admissions) from the MIMIC-IV database (2008-2022). Clinically significant electrolyte abnormalities (CSEA) were defined as documented potassium 5.0 mEq/L and sodium 145 mEq/L during hospitalization. Primary outcomes were 30-day all-cause readmission and mortality. We developed a clinical risk score incorporating electrolyte abnormalities and examined temporal electrolyte patterns. Results CSEA occurred in 705 patients (2.3%), with 96.7% achieving normalization by discharge. Patients with abnormalities had paradoxically lower 30-day readmission (3.9% vs 15.3%; adjusted HR 0.29, 95% CI 0.21-0.40) but substantially higher mortality (15.4% vs 7.0%; adjusted HR 1.93, 95% CI 1.57-2.38), reflecting competing mortality risk. Individual electrolyte abnormalities independently predicted mortality: hypokalemia HR 1.45 (1.28-1.65), hyperkalemia HR 1.67 (1.48-1.89), hyponatremia HR 1.34 (1.19-1.51). Temporal analysis revealed biphasic patterns—initial correction followed by recurrence—identified the highest-risk subset (composite event rates 27.6% for potassium, 28.5% for sodium). A five-variable risk score (electrolyte abnormality, age ≥75, chronic kidney disease, multiple admissions, coronary artery disease) achieved C-statistic 0.595 with 2.34-fold risk discrimination across categories. Conclusions CSEA independently predict mortality in heart failure patients despite paradoxically lower readmission rates due to competing risks. Biphasic electrolyte patterns identify particularly high-risk patients. Simple risk stratification using routinely collected electrolyte data may enhance post-discharge risk prediction and inform targeted monitoring strategies.
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Abstract
Background Electrolyte abnormalities commonly complicate heart failure management, yet their prognostic significance and optimal monitoring strategies remain incompletely characterized. We examined the prevalence, temporal patterns, and clinical outcomes associated with electrolyte abnormalities in hospitalized heart failure patients.
Methods
Retrospective cohort study of 30,678 heart failure patients (80,408 admissions) from the MIMIC-IV database (2008-2022). Clinically significant electrolyte abnormalities (CSEA) were defined as documented potassium 5.0 mEq/L and sodium 145 mEq/L during hospitalization. Primary outcomes were 30-day all-cause readmission and mortality. We developed a clinical risk score incorporating electrolyte abnormalities and examined temporal electrolyte patterns.
Results
CSEA occurred in 705 patients (2.3%), with 96.7% achieving normalization by discharge. Patients with abnormalities had paradoxically lower 30-day readmission (3.9% vs 15.3%; adjusted HR 0.29, 95% CI 0.21-0.40) but substantially higher mortality (15.4% vs 7.0%; adjusted HR 1.93, 95% CI 1.57-2.38), reflecting competing mortality risk. Individual electrolyte abnormalities independently predicted mortality: hypokalemia HR 1.45 (1.28-1.65), hyperkalemia HR 1.67 (1.48-1.89), hyponatremia HR 1.34 (1.19-1.51). Temporal analysis revealed biphasic patterns—initial correction followed by recurrence—identified the highest-risk subset (composite event rates 27.6% for potassium, 28.5% for sodium). A five-variable risk score (electrolyte abnormality, age ≥75, chronic kidney disease, multiple admissions, coronary artery disease) achieved C-statistic 0.595 with 2.34-fold risk discrimination across categories.
Conclusions
CSEA independently predict mortality in heart failure patients despite paradoxically lower readmission rates due to competing risks. Biphasic electrolyte patterns identify particularly high-risk patients. Simple risk stratification using routinely collected electrolyte data may enhance post-discharge risk prediction and inform targeted monitoring strategies.
Competing Interest Statement
The authors have declared no competing interest.
Funding Statement
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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 review committee at MIT and Beth Israel Deaconess Medical Center approved this database for research purposes. All procedures adhered to the ethical principles outlined in the Declaration of Helsinki.
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
Data Availability
All data in the article were obtained from the MIMIC-IV database (https://mimic.physionet.org/).
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