Admission and discharge sodium: chloride ratio in acute heart failure - the importance of electrolytes.

Abstract

Background: Chloride has prognostic implications in heart failure (HF). The sodium:chloride (Na:Cl) ratio gathers information of both ions. Objectives: To study the prognostic impact of Na:Cl ratio in acute HF. Methods: We retrospectively analysed patients included in an acute HF registry in 2009-2010. Primary endpoint: all-cause mortality. Follow-up: 1-year from admission to study the impact of admission Na:Cl ratio; 1-year post-discharge to study the discharge ratio impact. ROC curves of the association of Na, Cl, and the Na:Cl ratio with 1-year mortality were determined and the AUC compared. The association of Na:Cl ratio with mortality was assessed in multivariate analyses. Results: We studied 616 patients. Median admission Na:Cl ratio=1.34 (1.31-1.38). During 1-year since admission, 229 patients died, AUC for death-association of admission Na, Cl and Na:Cl ratio=0.42 (0.38-0.47), 0.39 (0.35-0.44) and 0.58 (0.53-0.63), respectively, with significant difference between Na:Cl ratio curve and the others. When admission Na:Cl ratio≥1.34, the multivariate-adjusted death-risk was 1.54 (1.17-2.02); 1.28 (1.04-1.58), per each 0.1 increase in ratio. In-hospital death rate was 4.1%, median discharge Na:Cl ratio=1.40 (1.37-1.45). During 1-year post-discharge, 205 patients (34.9%) died; AUC for Na, Cl and Na:Cl ratio: 0.45 (0.40-0.50), 0.41 (0.36-0.46) and 0.57 (0.52-0.62), with difference between Na:Cl ratio curve and the others. When Na:Cl ratio>1.43 (percentile 66.7), the adjusted-HR of death was 1.42 (1.03-1.95), p=0.03, 1.53 (1.22-1.91) per 0.1 increase. Conclusions: Elevated Na:Cl ratio is independently associated with all-cause death. Per each 0.1 increase in Na:Cl ratio at admission and discharged, there was a 28% and 53% higher risk, respectively.