Korean J Intern Med.  2015 Jul;30(4):460-470. 10.3904/kjim.2015.30.4.460.

Prognostic value of hyponatremia in heart failure patients: an analysis of the Clinical Characteristics and Outcomes in the Relation with Serum Sodium Level in Asian Patients Hospitalized for Heart Failure (COAST) study

• Yoo BS
• Park JJ
• Choi DJ
• Kang SM
• Hwang JJ
• Lin SJ
• Wen MS
• Zhang J
• Ge J
• COAST investigators

• KMID: 2366006
• DOI: http://doi.org/10.3904/kjim.2015.30.4.460

Abstract

BACKGROUND/AIMS
Hyponatremia is a well-known risk factor for poor outcomes in Western studies of heart failure (HF) patients. We evaluated the predictive value of hyponatremia in hospitalized Asian HF patients.
METHODS
The Clinical Characteristics and Outcomes in the Relation with Serum Sodium Level in Asian Patients Hospitalized for Heart Failure (the COAST) study enrolled hospitalized patients with systolic HF (ejection fraction < 45%) at eight centers in South Korea, Taiwan, and China. The relationship between admission sodium level and clinical outcomes was analyzed in 1,470 patients.
RESULTS
The mean admission sodium level was 138 +/- 4.7 mmol/L, and 247 patients (16.8%) had hyponatremia defined as Na+ < 135 mmol/L. The 12-month mortality was higher in hyponatremic patients (27.9% vs. 14.6%, p < 0.001), and hyponatremia was an independent predictor of 12-month mortality (hazard ratio, 1.72; 95% confidence interval, 1.12 to 2.65). During hospital admission, 57% of hyponatremic patients showed improvement without improvement in their clinical outcomes (p = 0.620). The proportion of patients with optimal medical treatment was only 26.5% and 44.2% at admission and discharge, respectively, defined as the combined use of angiotensin-converting-enzyme inhibitor/angiotensin receptor blocker and beta-blocker. Underuse of optimal medical treatment was more pronounced in hyponatremic patients.
CONCLUSIONS
In hospitalized Asian HF patients, hyponatremia at admission is common and is an independent predictor of poor clinical outcome. Furthermore, hyponatremic patients receive less optimal medical treatment than their counterparts.

Keyword

Hyponatremia; Predictor of clinical outcomes; Hospitalized heart failure; East Asians

MeSH Terms

Aged
Aged, 80 and over
Asia/epidemiology
*Asian Continental Ancestry Group
Biomarkers/blood
Cardiovascular Agents/therapeutic use
Disease-Free Survival
Female
Guideline Adherence
Healthcare Disparities
Heart Failure/*diagnosis/drug therapy/ethnology/mortality/physiopathology
*Hospitalization
Humans
Hyponatremia/blood/*diagnosis/drug therapy/ethnology/mortality
Male
Middle Aged
Practice Guidelines as Topic
Predictive Value of Tests
Proportional Hazards Models
Risk Factors
Sodium/*blood
Stroke Volume
Time Factors
Treatment Outcome
Biomarkers
Cardiovascular Agents
Sodium