Exploring the clinical impact of hyponatremia in hospitalized heart failure patients: a nationwide inpatient analysis

Introduction: Hyponatremia, observed in 15–30% heart failure (HF) patients, is associated with poor long-term outcomes in these patients. However, its prognostic significance during hospitalization remains unclear, therefore our study aims to fill this knowledge gap. Objective/ Hypothesis: Is hyponatremia associated with poor outcomes in hospitalized heart failure patients? Methods: National Inpatient Sample database was used to identify all adults with HF using ICD-10 codes. The patients were stratified into those with and without hyponatremia. Propensity score matching was performed to match the two cohorts in 1:1 ratio on age, gender, and comorbidities. Univariate analysis was performed pre- and post-matching to analyze outcomes. Results: Out of 15,900,000 patients admitted with HF, 2,329,359 had hyponatremia. Patients with hyponatremia were younger and had a higher prevalence of hypertension. Hyponatremia patients had significantly higher mortality (8.35% vs 5.71%), cardiac arrest (2.80% vs 1.67%), cardiogenic shock (5.13% vs 2.23%) need for mechanical ventilation (9.74% vs 7.08%), use of inotropic support (1.56% vs 0.81%), balloon pump utilization (0.81% vs 0.48%), ECMO use (0.14% vs 0.09%), arrhythmia (13.92% vs 12.56%) and acute kidney injury (36.66% vs 27.93%). Furthermore, hyponatremic patients experienced a statistically significant longer length of stay (9.34 days vs 6.35 days) and higher cost of hospitalization ($128276 vs $ 77576). Conclusion: Our findings underscore hyponatremia as not merely a laboratory abnormality, but a critical prognostic marker in the HF population. Early recognition and management of hyponatremia may be essential in improving clinical outcomes and reducing the economic burden associated with HF hospitalizations. Further prospective studies are warranted to explore causality and guide therapeutic strategies.