Longitudinal levels of pre-diuretic spot urinary sodium (UNa+) showed a decreasing trajectory over time in ambulatory outpatients with stable, chronic heart failure (HF), and lower levels of UNa+ were associated with increased risks in all-cause mortality and long-term, HF-related hospitalizations, according to a brief report published in JACC: Heart Failure.

In the observational, single-center prospective study conducted in Spain, Miguel Lorenzo, MD, et al., assessed 5,126 UNa+ determinations (collected from first void before daily diuretic intake) from a total of 1,179 patients (mean age 73 years; 42% women; 79% NYHA functional class II).

Baseline spot UNa+ was 72 mmol/L and 890 patients (76%) had baseline UNa+ >50 mmol/L. In total, 373 patients (32%) had an LVEF ≤40%, 190 (16%) an LVEF of 41-49% and 616 (52%) an LVEF ≥50%.

Results from an adjusted trajectory of UNa+ levels showed relatively stable values for the first year followed by a "progressive and significative decline (p<0.001)." At a median follow-up of 2.6 years, 300 patients had died (incidence rate, 10.3 per 100 person-years), and 173 patients had a total of 248 HF hospitalizations (incidence rate, 9.0 per 100 person-years) – the two endpoints of interest.

Lower pre-diuretic spot UNa+ levels as a linear predictor (per 10 mmol/L decrease) and specifically UNa+ <50 mmol/L were associated with both all-cause mortality (hazard rate [HR], 1.12 and HR, 2.06) and HF hospitalizations (HR, 1.09 and HR, 1.44).

"Current findings are also supported by solid pathophysiological postulates that link reduced sodium excretion in HF neurohormonal activation," write the authors, noting that the study expands "the evidence to a larger population, including a whole spectrum of patients across comorbidities, stage severity and LVEF."