Asymmetric Dimethylarginine Levels are Highly Associated With Atrial Fibrillation in an Elderly Population

Abstract

Background: The importance of endothelial dysfunction in atrial fibrillation (AF) is not clarified. The aim of this study was to evaluate endothelial dysfunction assessed by selected inflammatory and haemostatic endothelial markers and nitric oxide (NO) associated variables as related to the presence of AF in an elderly population. NO is known to express anti-thrombotic as well as vasoactive properties.

Methods: This is a cross sectional study of 75-year old subjects with AF (n = 62) and control subjects in sinus rhythm (n = 124), matched for gender. Fasting blood samples were collected for analyses of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO-synthase, L-arginine, E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and von Willebrand factor (vWF).

Results: Levels of vWF and ADMA were significantly higher in AF patients vs controls (P = 0.023 and P < 0.001, respectively) and the L-arginine/ADMA ratios were lower (P = 0.015), the latters still significant after adjustment for relevant covariates (P = 0.007 and P = 0.037, respectively). No significant differences in the levels of VCAM-1 and E-selectin were observed between the groups. When dividing the ADMA levels into quartiles there was a significant trend for having AF with increasing levels of ADMA (P < 0.001) with a cut-off at the 25th percentile (< 0.54 µmol/L), giving an adjusted OR for having AF of 12.46 (95% CI 3.11 - 49.86) (P < 0.001) with higher levels. A similar inverse trend was seen for the L-arginine/ADMA ratio.

Conclusion: Our population of 75-year-old AF patients had significantly impaired endothelial function assessed by increased levels of vWF, and more pronounced by high levels of ADMA. The results indicate AF in the elderly to be closely associated with the regulatory pathway of NO.

Keywords: ADMA; Atrial fibrillation; Elderly; Endothelial cell adhesion molecules; Endothelial dysfunction; Von Willebrand factor.

Figure 1

Number of patients with AF according to quartiles of vWF levels. The arrow indicates the cut-off value (median level) used for risk estimation.

Figure 2

Number of patients with AF according to quartiles of ADMA levels (a) and the L-arginine/ADMA ratio (b). The arrows indicate the cut-off value (25th percentile) used for risk estimation.