Association of Hyponatremia and Renal Function in Type 1 Cardiorenal syndrome.

BACKGROUND: Hyponatremia predicts type 1 cardiorenal syndrome in acute decompensated heart failure patients, which associates with poor outcome. Recovery from hyponatremia have been found to associate with better outcome in acute decompensated heart failure patients, but its prognostic value regarding renal function remains unknow. METHODS: We performed a secondary analysis of CARRESS-HF trial, all patients included had worsening renal function (≥0.3 mg/dl increase in serum creatinine than the nadir). The serum sodium levels of patients were evaluated at baseline, day 4 and day 7 after randomization. Patients were grouped according to the status of hyponatremia: recovery from hyponatremia, no hyponatremia, persistent hyponatremia, and new-onset hyponatremia. Their associations with persistent worsening renal function (serum creatinine ≥0.3 mg/dl higher than the nadir at discharge) were explored. RESULTS: 118 patients suffered from persistent worsening renal function. Baseline hyponatremia was not associated with persistent worsening renal function (odds ratio=0.495, P=0.086). Patients in recovery from hyponatremia group had a lowest risk of persistent worsening renal function among the study population. Further, baseline serum sodium level was not associated with the risk of persistent worsening renal function (odds ratio =1.055, P=0.233), while the increases of serum sodium level at day 4 (odds ratio =0.858, P=0.003) and at day 7 (odds ratio =0.821, P<0.001) significantly predicted a lower risk of persistent worsening renal function. CONCLUSIONS: Recovery from hyponatremia associates with a lower risk of persistent worsening renal function, suggesting that hyponatremia correction may improve renal outcomes in acute decompensated heart failure patients with type 1 cardiorenal syndrome.