Background: Homoarginine is an amino acid derivative that may increase nitric oxide availability and enhance endothelial function. The effect of the level of homoarginine on cardiovascular outcome and mortality is unknown.
Methods and results: We assessed cardiovascular and all-cause mortality according to homoarginine levels in a cohort of 3,305 subjects referred for coronary angiography from the LUdwigshafen RIsk and Cardiovascular Health (LURIC) Study. After investigating the relation of homoarginine with kidney function and markers of endothelial dysfunction, we explored its effects on adverse outcomes in a second high-risk cohort of 1244 patients with type 2 diabetes mellitus receiving maintenance hemodialysis (4D study [Die Deutsche Diabetes Dialyse Studie]). In the LURIC study, mean serum homoarginine levels were 2.6+/-1.1 micromol/L. During a median follow-up of 7.7 years, 766 patients died. After adjustments for age and sex, patients in the lowest quartile (<1.85 micromol/L) had a >4-fold higher rate of dying of cardiovascular disease (hazard ratio 4.1, 95% confidence interval 3.0 to 5.7) than patients in the highest quartile (>3.1 micromol/L). Lower homoarginine levels were associated with lower estimated glomerular filtration rate and higher levels of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Hemodialysed patients had lower mean homoarginine levels of 1.2+/-0.5 micromol/L and experienced a 5-fold increased mortality rate compared with LURIC patients (608 deaths during a median follow-up of 4 years). Homoarginine consistently affected mortality, which was 2-fold higher in 4D study patients in the lowest quartile (<0.87 micromol/L) than in patients in the highest quartile (>1.4 micromol/L).
Conclusions: Homoarginine levels are independently associated with cardiovascular and all-cause mortality in patients referred for coronary angiography and in patients undergoing hemodialysis. Future studies are needed to elucidate the underlying pathomechanisms.