Predictors of Mortality in Patients with Chronic Heart Failure: Is Hyponatremia a Useful Clinical Biomarker?
Manal M Alem
Department of Pharmacology, College of Clinical Pharmacy, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
Correspondence: Manal M Alem
Department of Pharmacology, College of Clinical Pharmacy, Imam Abdulrahman Bin Faisal University, PO Box 1982, Dammam 31441, Saudi Arabia
Background: Chronic heart failure (CHF) is a global health burden. Despite advances in treatment, there remain well-recognised morbidity and mortality. Risk stratification requires the identification and validation of biomarkers, old and new. Hyponatremia has re-emerged as a prognostic marker in CHF patients.
Methods: This is a retrospective cohort study on 241 CHF patients recruited from King Fahd Hospital of the University, Al-Khobar, Saudi Arabia (January 2005–December 2016). Their serum sodium and biochemical parameters were measured at baseline, along with 2-D echocardiographic assessments of left ventricular mass and ejection fraction. The primary endpoint was the association between hyponatremia and all-cause mortality (ACM) after a follow-up period of 24 months.
Results: Mean age of patients was 60.61 ± 12.63 (SD) years; 65.1% were males, and type 2 diabetes mellitus (DM) was present in 71%. Baseline serum sodium was 138.00 (136, 140) (median and interquartile range). Hyponatremia (< 135 meq/L) was present in 14.1%. After follow-up, 46 deaths had occurred. Multivariate Cox-proportional hazard model showed that type 2 DM, New York Heart Association (NYHA) class (III–IV vs I–II), age, and left ventricular mass index (LVMI) were significant and independent predictors of ACM, with HR 3.03 (95% CI; 1.13, 8.16) (P=0.028), HR 2.31 (95% CI; 1.11, 4.82) (P=0.026), HR 1.06 (95% CI; 1.03, 1.09) (P< 0.001), and HR 1.01 (95% CI; 1.00, 1.02) (P=0.039), respectively. Estimated glomerular filtration rate (eGFR) was not a significant predictor. Kaplan–Meier survival analysis was used for the analysis of NYHA class and hyponatremia interactions and showed that hyponatremia had an association with poorer survival in patients with NYHA class III–IV rather than I–II (Log-rank test, P= 0.0009).
Conclusion: Hyponatremia was a feature in CHF patients, and ACM was predicted by type 2 DM, NYHA class, age, and LVMI. Hyponatremia impact on survival was in patients with more advanced disease.
Keywords: hyponatremia, electrolyte disturbance, heart failure, left ventricular mass index, ejection fraction, all-cause mortality, Saudi Arabia
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