Age-dependent effects of homocysteine and dimethylarginines on cardiovascular mortality in claudicant patients with lower extremity arterial disease

Abstract

The association among serum homocysteine (HCY), symmetric dimethylarginine (SDMA), and asymmetric dimethylarginine (ADMA) is of interest in endothelial dysfunction, although the underlying pathology is not fully elucidated. We investigated the relationship of HCY with SDMA and ADMA regarding their long-time outcome and the age dependency of HCY, SDMA, and ADMA values in claudicant patients with lower extremity arterial disease. 120 patients were included in a prospective observational study (observation time 7.96 ± 1.3 years) with cardiovascular mortality as the main outcome parameter. Patients with intermittent claudication prior to their first endovascular procedure were included. HCY, SDMA, and ADMA were measured by high-performance liquid chromatography. Cutoff values for HCY (≤/>15 µmol/l), SDMA (≤/>0.75 µmol/l), and ADMA (≤/>0.8 µmol/l) differed significantly regarding cardiovascular mortality (p < 0.001, p < 0.001, p = 0.017, respectively). Age correlated significantly with HCY (r = 0.393; p < 0.001), SDMA (r = 0.363; p < 0.001), and ADMA (r = 0.210; p = 0.021). HCY and SDMA (r = 0.295; p = 0.001) as well as SDMA and ADMA (r = 0.380; p < 0.001) correlated with each other, while HCY and ADMA did not correlate (r = 0.139; p = 0.130). Patients older than 65 years had higher values of HCY (p < 0.001) and SDMA (p = 0.01), but not of ADMA (p = 0.133). In multivariable linear regression, age was the only significant independent risk factor for cardiovascular death (beta coefficient 0.413; 95% CI 0.007–0.028; p = 0.001). Age correlated significantly with HCY, SDMA, and ADMA. However, only age was an independent predictor for cardiovascular death. Older patients have higher values of HCY and SDMA than younger subjects suggesting age-adjusted cutoff values of HCY and SDMA due to strong age dependency.