A total of 882 consecutive hospitalized AHF patients were retrospectively enrolled in this study. Sodium levels were evaluated on days 1 and 3 of admission, and patients were classified into three groups: patients with hyponatremia on admission and day 3 (hypo-hypo group); patients with hyponatremia on admission and normonatremia on day 3 (hypo-normo group); and patients with normonatremia on admission (normo group).
Hyponatremia (sodium ≤135 mEq/L) was observed in 14.3% of cases. In multivariate linear regression analysis, age (standardized beta = 0.084), male gender (standardized beta = −0.072), history of ischemic heart disease (standardized beta = −0.069), baseline sodium level (standardized beta = −0.435), and tolvaptan use (standardized beta = 0.093) were independent determinants of changes in sodium level from day 1 to day 3. In-hospital mortality rates were significantly higher in the hypo-hypo group (23.7%) and hypo-normo group (9.7%) than the normo group (6.9%) (p < 0.001). After adjustment for covariates, both hypo-normo (OR: 0.28, 95% CI: 0.08–0.93, p = 0.038) and normo (OR: 0.42, 95% CI: 0.20–0.88, p = 0.022) groups showed significantly lower in-hospital mortality rates than the hypo-hypo group.
Early recovery from hyponatremia in AHF patients is associated with lower in-hospital mortality rate.