Serial sodium values and adverse outcomes in heart failure with preserved ejection fraction

Abstract

ObjectiveThe purpose of our study is to examine whether serial measurements of serum sodium values after diagnosis identify a higher-risk subset of patients with heart failure with preserved ejection fraction. MethodsWe identified 50,932 subjects with HFpEF with 759,577 recorded sNa measurements (mean age 72 ± 11 years) using a validated algorithm in the VA national database from 2002 to 2012. We examined the association of repeated measures of sNa with mortality using a multivariable Cox proportional hazards model. ResultsAfter a median follow-up of 2.9 years (IQR: 1.2–5.4), 19,011 deaths occurred. After adjusting for age, sex, race, BMI, glomerular filtration rate, potassium, coronary artery disease, hypertension, hyperlipidemia, atrial fibrillation, pulmonary disease, diabetes, anemia, and medications, we found J-shaped associations of serum sodium with mortality. HRs for all-cause mortality were 2.48 (95% CI: 2.38–2.60) for the sNA 115.00–133.99 category; and 1.40 (95% CI: 1.35–1.46) for the sNA 143.00–175.00 category compared to the 137.01–140.99 category (ref). We used generalized estimating equation-based negative binomial regression to compute the incidence density ratios (IDR) to examine days hospitalized for heart failure and for all causes. There were a total of 1,275,614 days of all-cause hospitalization and 104,006 days of heart-failure hospitalization. The IDRs for the lowest sNA group were 2.03 (95% CI: 1.90–2.18) for all-cause hospitalization and 1.73 (95% CI: 1.39–2.16) for heart-failure hospitalization. ConclusionsOur findings suggest that monitoring of serum sodium values during longitudinal follow-up can identify HFpEF patients at risk of adverse outcomes.