Introduction.

Urinary sodium has been proposed as a prognostic marker and indicator of the diuretic response in patients with heart failure. However, study results are heterogeneous.

Objective.

To evaluate the spot urinary sodium level as a risk factor for mortality in patients with decompensated heart failure.

Materials and methods.

We conducted a case-control study nested in a prospective cohort of patients with decompensated heart failure. The primary outcome was mortality at 180 days. The risk factors associated with mortality were evaluated through a bivariate analysis. Differences in clinical variables between groups with urinary sodium greater than or lesser than 70 mEq/L were analyzed.

Results.

The study included 79 patients; 15 died at 180 days. Their mean age was 68.9 years (SD=± 13.8); 30 were women (38%), and 15 (18.9%) had urinary sodium <70 mEq/L. In the bivariate analysis, a significant association was found between mortality and past medical history of hospitalizations, SBP<90 mm Hg, the use of inotropes, and urinary sodium <70 mEq/L. Regarding clinical characteristics, patients with low urinary sodium level in the last year were hospitalized more frequently with hyponatremia and hypotension at admission.

Conclusion.

Patients with urinary sodium <70 mEq/L had more severe signs. In a bivariate analysis, urinary sodium was associated with mortality at 180 days.

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