Progression of Hyponatremia is Associated With Increased Cardiac Mortality in Patients Hospitalized for Acute Decompensated Heart Failure

BackgroundAlthough hyponatremia during hospitalization for acute decompensated heart failure (ADHF) has been reported to correlate with poor prognosis, few studies have examined the effect of progression of hyponatremia on cardiac prognosis in ADHF patients who were normonatremic at admission.Methods and ResultsConsecutive ADHF patients (n = 662) categorized as New York Heart Association Class III or IV were investigated retrospectively. Of these patients, 634 who survived to discharge were examined and 531 were normonatremic (serum sodium concentration [Na] ≥ 135 and ≤ 145 mmol/L) at admission. The 531 patients were divided into 2 groups: the non-developed group, who remained normonatremic at discharge (n = 455), and the developed group, who had progressed to hyponatremia (Na < 135 mmol/L) at discharge (n = 76). The cardiac event–free rate after 12 months was significantly lower in the developed group than in the non-developed group (22% vs. 71%; P < .0001). Although their baseline levels of brain natriuretic peptide and left ventricular ejection fraction were similar before discharge, the patients in the developed group exhibited higher fractional excretion of sodium and received higher doses of diuretics than did those in the non-developed group.ConclusionOur data suggest that progression to hyponatremia during hospitalization is a robust predictor of poor cardiac prognosis in ADHF patients who were normonatremic at admission.