Serum phosphate and long-term outcome among patients with stable heart failure.

Background: Elevated serum phosphate levels are associated with excess risk for cardiovascular mortality in patients with and without chronic kidney disease and with increased risk for incident heart failure. We determined the association of serum phosphate concentrations with disease severity and long-term outcome in patients with overt heart failure.

Methods And Results: Clinical and laboratory parameters of 974 ambulatory heart failure patients were evaluated. Prevalence of elevated phosphate levels (>4.5 mg/dL) was 5.8% in men and 6.0% in women. Phosphate was significantly correlated with disease severity as assessed by New York Heart Association class, left ventricular ejection fraction, and N-terminal pro-B-type natriuretic peptide (P < .01, respectively). Multivariate sex-stratified Cox regression analysis adjusted for various clinically relevant covariates revealed baseline phosphate to be independently associated with death from any cause or heart transplantation (HR 1.26 [95% CI 1.04-1.52]; P < .001). This relation was maintained in patients with and without chronic kidney disease. After categorization based on quartiles of phosphate levels, a graded, independent relation between phosphate and outcome was observed (P for trend <.001).

Conclusions: We found a graded, independent relation between serum phosphate and adverse outcome in patients with stable heart failure. Also, serum phosphate was related to disease severity. These findings further highlight the clinical importance of serum phosphate in cardiovascular disease.