Prognostic Role of Serum Chloride Levels in Acute Decompensated Heart Failure

Abstract

Acute decompensated heart failure (ADHF) can be complicated by electrolyte abnormalities. While there is an abundance of knowledge regarding the clinical significance of serum sodium levels, to our knowledge, there are limited data regarding the prognostic significance of serum chloride levels in ADHF. We hypothesize that lower serum chloride levels will be associated with long-term mortality after admission for ADHF. We reviewed 1,318 consecutive patients with established chronic heart failure, with implantable cardioverter defibrillators, admitted for ADHF to the Cleveland Clinic between 7/2008 and 12/2013 and also validated our findings in an independent ADHF cohort from the University of Pennslvania (N=876). All patients were followed for all-cause mortality. Cox-proportional hazards models were adjusted for admission sodium, blood urea nitrogen, length of stay, age, ischemic cardiomyopathy, beta-blocker use, renin-angiotensin system inhibitor use, and mineralocorticoid antagonist use. In our cohort (median age 69 [59-77] years, LVEF 27% [19-45], NT-proBNP 4817 pg/mL [2415-9536], sodium 137 meq/L [135-140], and 70% male) the median admission chloride level was 101 meq/L [97-104] and there were 359 deaths over 2,261 person*years of follow-up. Admission chloride levels were inversely associated with long-term mortality (HR per unit change 0.94; 95% CI 0.92-0.95; p<.001). After multivariable risk-adjustment, admission chloride levels remained independently associated with mortality (HR per unit change 0.93; 95% CI 0.90-0.97; p<.001, Figure 1) in contrast to admission sodium levels which were no longer significant (p=0.2). Results were similar in the validation cohort in unadjusted (HR per unit change for mortality-risk within 1 year 0.93; 95% CI 0.91-0.95; p<.001) and multivariable risk-adjusted analysis (HR per unit change for mortality-risk within 1 year 0.95; 95% CI 0.92-0.99; p=0.01). These observations in a contemporary ADHF cohort, with external validation, suggest that serum chloride levels are independently and inversely associated with mortality. The prognostic role of serum sodium in ADHF was diminished in comparison to chloride levels.