Background Homoarginine is an amino acid which may play a role in nitric oxide and energy metabolism. Low homoarginine concentrations have previously been linked to increased mortality, but the underlying mechanisms remain unknown.

Objectives To investigate whether serum homoarginine concentrations are associated with myocardial function, energy metabolism and fatal events.

Design and patients Serum homoarginine concentrations were measured in 3305 Caucasian patients who were referred for coronary angiography at a tertiary care centre in Germany. After baseline examinations (1997–2000), patients were followed-up with respect to specific causes of death.

Results Homoarginine concentration correlated positively with angiographic ejection fraction and was inversely associated with N-terminal pro-B-type natriuretic peptide (p<0.001 for both). Variables of energy metabolism (guanidinoacetate and creatine) were significantly associated with homoarginine concentration (p<0.001 for both). Over a median follow-up time of 9.9 years, 991 patients died, including 258 sudden cardiac deaths, 148 heart failure deaths and 105 fatal myocardial infarctions. Multivariable adjusted Cox proportional HRs (with 95% CI) for the first versus the fourth homoarginine quartile were 2.44 (1.60 to 3.73) for sudden cardiac deaths, 3.44 (1.89 to 6.24) for heart failure deaths, and 3.78 (1.77 to 8.06) for fatal myocardial infarctions.

Conclusions Homoarginine deficiency is associated with myocardial dysfunction and significantly increased risk of fatal cardiovascular events and may be related to poor energy metabolism. Further studies are warranted to explore the significance of homoarginine metabolism in risk stratification and treatment of heart diseases.