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Pereverzeva KG, Yakushin SS, Cherkasova YO, Korchagina TA, Kuznetsov DA. Factors associated with one-year mortality in patients with hyponatremia hospitalized in a cardiology department: An exploratory retrospective cohort study. World J Cardiol 2026; 18(11): 125738 [DOI: 10.4330/wjc.125738]
World J Cardiol. Nov 26, 2026; 18(11): 125738 Published online Nov 26, 2026. doi: 10.4330/wjc.125738
Factors associated with one-year mortality in patients with hyponatremia hospitalized in a cardiology department: An exploratory retrospective cohort study
Kristina G Pereverzeva, Sergey S Yakushin, Yulia O Cherkasova, Tatiana A Korchagina, Dmitry A Kuznetsov
Kristina G Pereverzeva, Sergey S Yakushin, Yulia O Cherkasova, Tatiana A Korchagina, Dmitry A Kuznetsov, Department of Hospital Therapy with a Course in Medical and Social Expertise, Federal State Budgetary Educational Institution of Higher Education I.P. Pavlov Ryazan State Medical University of the Ministry of Health of the Russian Federation, Ryazan 390026, Ryazanskaya Oblast’, Russia
Author contributions: Pereverzeva KG and Yakushin SS contributed to the study conceptualization and project administration; Pereverzeva KG was responsible for the methodology, data curation, drafting of the original manuscript, and editing of subsequent versions; Yakushin SS provided critical resources and reviewed the manuscript; Cherkasova YO, Korchagina TA, and Kuznetsov DA performed patient enrollment, acquisition of clinical data, and collection of the study material. All authors approved the final version for publication.
AI contribution statement: DeepSeek (version V3, 2025) was used for language editing and translation of the manuscript.
Institutional review board statement: This study was approved by the Local Ethics Committee of Ryazan State Medical University, No. 7.
Informed consent statement: Upon hospitalization, all patients signed a general informed consent form for medical care. For this study, all data were de-identified prior to analysis. The Institutional Review Board approved the study and granted a waiver of additional informed consent, as the study involved no direct patient contact and used only routinely collected clinical data from medical records and electronic registries.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Data sharing statement: The statistical code used for the analyses and the datasets analyzed during the current study can be obtained from the corresponding author upon reasonable request.
Corresponding author: Sergey S Yakushin, Professor, Department of Hospital Therapy with a Course in Medical and Social Expertise, Federal State Budgetary Educational Institution of Higher Education I.P. Pavlov Ryazan State Medical University of the Ministry of Health of the Russian Federation, No. 96 Stroykova Street, Ryazan 390026, Ryazanskaya Oblast’, Russia. s.yakushin@rzgmu.ru
Received: July 17, 2026 Revised: September 13, 2026 Accepted: November 2, 2026 Published online: November 26, 2026 Processing time: 123 Days and 17.4 Hours
Abstract
BACKGROUND
Hyponatremia is a common electrolyte disorder in hospitalized cardiac patients and is associated with increased mortality. However, data on factors associated with one-year mortality in patients with hyponatremia in real-world clinical practice are limited, and the temporal relationship between in-hospital predictors and long-term outcomes remains uncertain.
AIM
To explore factors associated with one-year mortality in cardiac inpatients with hyponatremia and assess the robustness of these associations in sensitivity analyses.
METHODS
This retrospective single-center cohort study included 119 patients (mean age 71.2 ± 12.7 years, 48.7% female) hospitalized in a cardiology department with hypotonic hyponatremia. Patients with acute coronary syndrome and/or myocardial infarction were excluded. The primary endpoint was all-cause death within 1 year, ascertained through the regional electronic death registry. Cox regression was used. Sensitivity analyses excluding in-hospital deaths and Firth’s penalized Cox regression were performed.
RESULTS
The one-year mortality rate was 44.5% (53/119). In the primary multivariable Cox model, stage II chronic heart failure (CHF) [hazard ratio (HR) 8.86; 95% confidence interval (CI): 1.81-43.39; P = 0.007], minimum sodium (HR 0.94; 95%CI: 0.89-1.00; P = 0.040), and peak creatine kinase-MB (CK-MB) (HR 1.02; 95%CI: 1.00-1.04; P = 0.002) were associated with one-year mortality. However, in a sensitivity analysis excluding in-hospital deaths, these associations were no longer statistically significant. In Firth’s penalized model, CK-MB (HR 1.02; 95%CI: 1.01-1.04; P = 0.007) and stage II CHF (HR 6.60; 95%CI: 1.67-33.37; P = 0.007) remained significant, whereas minimum sodium did not (P = 0.117). Non-linearity was not detected for sodium (P = 0.459) or CK-MB (P = 0.182).
CONCLUSION
In this exploratory analysis, CK-MB and stage II CHF were more robustly associated with one-year mortality than hyponatremia. The sodium association was not confirmed in sensitivity analyses. These findings are hypothesis-generating and require prospective validation.
Core Tip: Hyponatremia in cardiac inpatients is associated with high one-year mortality (44.5%). In this exploratory analysis, factors associated with one-year mortality included stage II chronic heart failure, lower minimum sodium, and elevated creatine kinase-MB activity. However, the association with minimum sodium was not confirmed in sensitivity analyses, whereas creatine kinase-MB and stage II chronic heart failure remained significant in the Firth’s penalized model. These findings are hypothesis-generating and require prospective validation.
