The effect of exercise on vascular health in chronic kidney disease: a systematic review and meta-analysis of randomized controlled trials.

Patients with chronic kidney disease (CKD) are at increased risk of cardiovascular disease. This increased risk cannot be fully explained by traditional risk factors such as hypertension. Endothelial dysfunction and arterial stiffness have been suggested as factors that explain some of the increased risk and are independently associated with important cardiovascular outcomes in patients with CKD. Studies in other disease populations have shown the positive effects of exercise on vascular dysfunction. The aim of this review was to determine whether exercise training interventions improve measures of vascular function and morphology in patients across the spectrum of CKD and which exercise training interventions are most efficacious. A systematic search of Medline, Embase, and the Cochrane Central Register identified 25 randomized controlled trials. Only randomized control trials using an exercise intervention with a nonexercising control group and at least one measure of vascular function or morphology were included. Participants were patients with nondialysis CKD or transplant patients or those requiring dialysis therapy. A systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A meta-analysis was completed for pulse wave velocity, augmentation index, and measures of endothelium-dependent vasodilation. Data from 25 studies with 872 participants showed that exercise training reduced pulse wave velocity and augmentation index but had no effect on endothelium-dependent vasodilation. Subgroup analyses suggested that exercise interventions of at least moderate intensity were more likely to be effective. Limitations included the absence of observational studies or other interventions aimed at increasing habitual physical activity. Further studies are warranted to investigate which are the most effective exercise interventions.NEW & NOTEWORTHY A thorough systematic review and meta-analysis of the effects of exercise training on measures of vascular function in patients with chronic kidney disease, including arterial stiffness and endothelial function, were conducted. Subgroup analyses investigated how differences in exercise training, according to frequency, intensity, type, and timing, have an impact on the efficacy of the intervention.

The deleterious effects of acute hypoxia on microvascular and large vessel endothelial function.

NEW FINDINGS: What is the central question of this study? The aim was primarily to determine the effect of hypoxia on microvascular function and secondarily whether superior cardiorespiratory fitness is protective against hypoxia-induced impairment in vascular function. What is the main finding and its importance? Hypoxia reduced endothelium-dependent but not endothelium-independent microvascular function. The extent of impairment was twofold higher in the microcirculation compared with the large blood vessels. This study suggests that individuals with superior cardiorespiratory fitness might preserve microvascular function in hypoxia. These findings highlight the sensitivity of the microvascular circulation to hypoxia. ABSTRACT: Hypoxia is associated with diminished bioavailability of the endothelium-derived vasodilator, nitric oxide (NO). Diminished NO bioavailability can have deleterious effects on endothelial function. The endothelium is a heterogeneous tissue; therefore, a comprehensive assessment of endothelial function is crucial to understand the significance of hypoxia-induced endothelial dysfunction. We hypothesized that acute hypoxia would have a deleterious effect on microvascular and large vessel endothelial function. Twenty-nine healthy adults [24 (SD = 4 ) years of age] completed normoxic and hypoxic [inspired O2  fraction = 0.209] trials in this double-blinded, counterbalanced crossover study. After 30 min, we assessed the laser Doppler imaging-determined perfusion response to iontophoresis of ACh as a measure of endothelium-dependent microvascular function and iontophoresis of sodium nitroprusside as a measure of endothelium-independent microvascular function. After 60 min, we assessed brachial flow-mediated dilatation as a measure of large vessel endothelial function. Thirty minutes of hypoxia reduced endothelium-dependent microvascular function determined by the perfusion response to ACh (median difference (x̃∆) = -109% {interquartile range: 542.7}, P < 0.05), but not endothelium-independent microvascular function determined by the perfusion response to sodium nitroprusside (x̃∆ = 69% {interquartile range: 453.7}, P = 0.6). In addition, 60 min of hypoxia reduced allometrically scaled flow-mediated dilatation compared with normoxia ( x¯Δ=-1.19 [95% CI = -1.80, -0.58 (Confidence Intervals)]%, P < 0.001). The decrease in microvascular endothelial function was associated with cardiorespiratory fitness (r  = 0.45, P = 0.02). In conclusion, acute exposure to normobaric hypoxia significantly reduced endothelium-dependent vasodilatory capacity in small and large vessels. Collectively, these findings highlight the sensitivity of the microvascular circulation to hypoxic insult, particularly in those with poor cardiorespiratory fitness.

Bilateral regional extracranial blood flow regulation to hypoxia and unilateral duplex ultrasound measurement error.

NEW FINDINGS: What is the central question of this study? Is blood flow regulation to hypoxia different between the internal carotid arteries (ICAs) and vertebral arteries (VAs), and what is the measurement error in unilateral extracranial artery assessments compared to bilateral? What is the main finding and its importance? ICA and VA blood flow regulation to hypoxia is comparable when factoring for vessel type and vessel side. Compared to bilateral assessment, vessels assessed unilaterally had individual measurement errors of up to 37%. Assessing the vessel with the larger resting blood flow, not the left or right vessel, reduces unilateral measurement error. ABSTRACT: Whether blood flow regulation to hypoxia is similar between left and right internal carotid arteries (ICAs) and vertebral arteries (VAs) is unclear. Extracranial blood flow is regularly calculated by doubling a unilateral assessment; however, lateral artery differences may lead to measurement error. This study aimed to determine extracranial blood flow regulation to hypoxia when factoring for vessel type (ICAs or VAs) and vessel side (left or right) effects, and to investigate unilateral assessment measurement error compared to bilateral assessment. In a repeated-measures crossover design, extracranial arteries of 44 participants were assessed bilaterally by duplex ultrasound during 90 min of normoxic and poikilocapnic hypoxic (12.0% fraction of inspired oxygen) conditions. Linear mixed model analyses revealed no Condition × Vessel Type × Vessel Side interaction for blood flow, vessel diameter and flow velocity (all P > 0.05) indicating left and right ICA and VA blood flow regulation to hypoxia was similar. Bilateral hypoxic reactivity was comparable (ICAs, 1.4 (1.0) vs. VAs, 1.7 (1.1) Δ%·Δ SpO2-1 ; P = 0.12). Compared to bilateral assessment, unilateral mean measurement error of the relative blood flow response to hypoxia was up to 5%, but individual errors reached 37% and were greatest in ICAs and VAs with the smaller resting blood flow due to a ratio-scaling problem. In conclusion, left and right ICA and VA regulation to hypoxia is comparable when factoring for vessel type and vessel side. Assessing the ICA and VA vessels with the larger resting blood flow, not the left or right vessel, reduces unilateral measurement error.

Subclinical atherosclerosis in systemic sclerosis and rheumatoid arthritis: a comparative matched-cohort study.

Systemic autoimmune inflammatory disorders confer a higher risk of cardiovascular (CV) disease leading to increased morbidity and mortality and reduced life expectancy compared to the general population. CV risk in systemic sclerosis (SSc) has not been studied extensively but surrogate markers of atherosclerosis namely carotid intima media thickness (cIMT) and pulse wave velocity (PWV) are impaired in some but not all studies in SSc patients. The aim of this study was to investigate the prevalence of subclinical atherosclerosis assessed by cIMT and PWV between two well-characterized SSc and Rheumatoid Arthritis (RA) cohorts. Consecutive SSc patients attending the Scleroderma Clinic were compared with RA patients recruited in the Dudley Rheumatoid Arthritis Co-morbidity Cohort (DRACCO), a prospective study examining CV burden in RA. Augmentation Index (Aix75) and cIMT were measured in all participants. Propensity score matching was utilised to select patients from the two cohorts with similar demographic characteristics, CV risk factors and inflammatory load. Unpaired analysis was performed using unpaired t test for continuous variables and χ2 test for dichotomous variables. Statistical analysis was repeated using paired t test for continuous normal variables and McNemar's test for dichotomous variables. Fifty five age- and sex-matched SSc and RA patients were included in the analysis. No difference was demonstrated between SSc and RA subjects regarding cIMT (0.66 mm vs 0.63 mm, respectively) and Aix75% measurements (33.4 vs 31.7, respectively) neither in paired (p = 0.623 for cIMT and p = 0.204 for Aix%) nor in unpaired t test analysis (p = 0.137 for cIMT and p = 0.397 for AIx%). The results of this comparative study show that subclinical atherosclerosis is comparable between SSc and RA, a systemic disease with well-defined high atherosclerotic burden. Such findings underscore the importance of CV risk management in SSc in parallel with other disease-related manifestations.

Prediction of cardiovascular events in rheumatoid arthritis using risk age calculations: evaluation of concordance across risk age models.

BACKGROUND: In younger individuals, low absolute risk of cardiovascular disease (CVD) may conceal an increased risk age and relative risk of CVD. Calculation of risk age is proposed as an adjuvant to absolute CVD risk estimation in European guidelines. We aimed to compare the discriminative ability of available risk age models in prediction of CVD in rheumatoid arthritis (RA). Secondly, we also evaluated the performance of risk age models in subgroups based on RA disease characteristics. METHODS: RA patients aged 30-70 years were included from an international consortium named A Trans-Atlantic Cardiovascular Consortium for Rheumatoid Arthritis (ATACC-RA). Prior CVD and diabetes mellitus were exclusion criteria. The discriminatory ability of specific risk age models was evaluated using c-statistics and their standard errors after calculating time until fatal or non-fatal CVD or last follow-up. RESULTS: A total of 1974 patients were included in the main analyses, and 144 events were observed during follow-up, the median follow-up being 5.0 years. The risk age models gave highly correlated results, demonstrating R2 values ranging from 0.87 to 0.97. However, risk age estimations differed > 5 years in 15-32% of patients. C-statistics ranged 0.68-0.72 with standard errors of approximately 0.03. Despite certain RA characteristics being associated with low c-indices, standard errors were high. Restricting analysis to European RA patients yielded similar results. CONCLUSIONS: The cardiovascular risk age and vascular age models have comparable performance in predicting CVD in RA patients. The influence of RA disease characteristics on the predictive ability of these prediction models remains inconclusive.

The Effects of Beetroot Juice on Blood Pressure, Microvascular Function and Large-Vessel Endothelial Function: A Randomized, Double-Blind, Placebo-Controlled Pilot Study in Healthy Older Adults.

: Dietary nitrate (NO3-) has been reported to improve endothelial function (EF) and blood pressure (BP). However, most studies only assess large-vessel EF with little research on the microvasculature. Thus, the aim of the present pilot study is to examine NO3- supplementation on microvascular and large-vessel EF and BP. Twenty older adults (63 ± 6 years) were randomized to a beetroot juice (BRJ) or placebo (PLA) group for 28 (±7) days and attended three laboratory visitations. Across visitations, blood pressure, microvascular function and large-vessel EF were assessed by laser Doppler imaging (LDI) with iontophoresis of vasoactive substances and flow-mediated dilatation (FMD), respectively. Plasma NO3-concentrations, BP and the presence of NO3- reducing bacteria were also assessed. Plasma NO3- increased following two weeks of BRJ supplementation (p = 0.04) along with a concomitant decrease in systolic and diastolic BP of approximately -6 mmHg and -4 mmHg, respectively (p = 0.04; p = 0.01, respectively). BP remained unchanged in the PLA group. There were no significant differences in endothelium-dependent or endothelium-independent microvascular responses between groups. FMD increased by 1.5% following two weeks of BRJ (p = 0.04), with only a minimal (0.1%) change for the PLA group. In conclusion, this pilot study demonstrated that medium-term BRJ ingestion potentially improves SBP, DBP and large-vessel EF in healthy older adults. The improvements observed in the present study are likely to be greater in populations presenting with endothelial dysfunction. Thus, further prospective studies are warranted in individuals at greater risk for cardiovascular disease.

Comparison of the effects of exercise and anti-TNF treatment on cardiovascular health in rheumatoid arthritis: results from two controlled trials.

People with rheumatoid arthritis (RA) are at increased risk for cardiovascular disease (CVD). Both pharmacological treatment and exercise are suggested in the management of CVD risk in RA. This study explored the effects of exercise and anti-TNF treatment on CVD risk in RA. Twenty RA patients (70% female, 50 (10) years) completed a 3-month exercise intervention and 23 RA patients (65% female, 54 (15) years) started anti-TNF treatment. Markers of disease activity, CVD risk, and vascular function were assessed before and after 3-months of intervention/treatment. Both exercise and anti-TNF treatment improved functional ability and fatigue, anti-TNF treatment was more successful in improving inflammation, disease activity, functional ability and pain. Exercise induced a reduction in overall CVD risk and improvement in vascular function, which was significantly different from anti-TNF treatment where no such changes were found. These findings showed that exercise and anti-TNF had differential effects on CVD risk in RA, and should be combined for optimal CVD risk reduction. Whereas anti-TNF treatment is likely to impact on CVD risk through reducing the systemic inflammatory load, exercise should be recommended to people with RA as an effective self-management strategy to reduce CVD risk further. Once RA patients have responded successfully to anti-TNF treatment, increasing exercise should be encouraged to reduce the risk for CVD. Thus, supporting exercise programmes when the disease is controlled, is likely to enhance the uptake and the maintenance of exercise, which will result in additional benefits to cardiovascular health and wellbeing in people with RA.

Sitting time is negatively related to microvascular endothelium-dependent function in rheumatoid arthritis.

BACKGROUND: Sedentary behaviour is linked to increased cardiovascular disease risk in Rheumatoid Arthritis (RA), but the biological processes underlying this relationship are not understood. OBJECTIVES: To investigate the cross-sectional associations of habitual sedentary behaviour, with endothelial function in RA. METHODS: Sixty-eight RA patients (Mage = 55 ±â€¯12 years) underwent Laser Doppler Imaging with iontophoresis, to assess microvascular endothelium-dependent (acetylcholine, ACh) and endothelium-independent (sodium nitroprusside, SNP) function. Large-vessel endothelium-dependent and endothelium-independent functions were measured via flow-mediated dilation (FMD) and glyceryl trinitrate dilation (GTN), respectively. Habitual sedentary behaviour (hours/week sitting) was self-reported (International Physical Activity Questionnaire). RESULTS: Regressions revealed sitting time significantly negatively predicted microvascular endothelium-dependent function (ACh, unstandardizedß = -3.25, p = .02, 95% CI [-6.07, -.42], R2 = 0.06), but did not associate with other endothelial function outcomes (SNP, FMD, GTN). CONCLUSION: Habitual sedentary behaviour (sitting time) appears to be adversely linked to microvascular endothelium-dependent function among people living with RA.

Impact of risk factors associated with cardiovascular outcomes in patients with rheumatoid arthritis.

OBJECTIVES: Patients with rheumatoid arthritis (RA) have an excess risk of cardiovascular disease (CVD). We aimed to assess the impact of CVD risk factors, including potential sex differences, and RA-specific variables on CVD outcome in a large, international cohort of patients with RA. METHODS: In 13 rheumatology centres, data on CVD risk factors and RA characteristics were collected at baseline. CVD outcomes (myocardial infarction, angina, revascularisation, stroke, peripheral vascular disease and CVD death) were collected using standardised definitions. RESULTS: 5638 patients with RA and no prior CVD were included (mean age: 55.3 (SD: 14.0) years, 76% women). During mean follow-up of 5.8 (SD: 4.4) years, 148 men and 241 women developed a CVD event (10-year cumulative incidence 20.9% and 11.1%, respectively). Men had a higher burden of CVD risk factors, including increased blood pressure, higher total cholesterol and smoking prevalence than women (all p<0.001). Among the traditional CVD risk factors, smoking and hypertension had the highest population attributable risk (PAR) overall and among both sexes, followed by total cholesterol. The PAR for Disease Activity Score and for seropositivity were comparable in magnitude to the PAR for lipids. A total of 70% of CVD events were attributable to all CVD risk factors and RA characteristics combined (separately 49% CVD risk factors and 30% RA characteristics). CONCLUSIONS: In a large, international cohort of patients with RA, 30% of CVD events were attributable to RA characteristics. This finding indicates that RA characteristics play an important role in efforts to reduce CVD risk among patients with RA.

Genetic variations in the alanine-glyoxylate aminotransferase 2 (AGXT2) gene and dimethylarginines levels in rheumatoid arthritis.

Rheumatoid arthritis (RA) is associated with high rates of cardiovascular events mainly due to coronary and cerebrovascular atherosclerotic disease. Asymmetric (ADMA) and symmetric (SDMA) dimethylarginines are endogenous inhibitors of nitric oxide synthase and have been repeatedly linked with adverse cardiovascular outcomes in the general population and various disease settings. Alanine-glyoxylate aminotransferase 2 (AGTX2) is considered an alternative metabolic pathway contributing to the clearance of dimethylarginines in humans. The aim of the current study was to investigate the effect of specific AGXT-2 gene polymorphisms on circulating levels of ADMA or SDMA in patients with RA. Serum ADMA and SDMA levels were measured in 201 individuals with RA [median age: 67 years (IQR: 59-73), 155 females]. Two single nucleotide polymorphisms (SNPs) in the AGXT-2 gene-rs37369 and rs28305-were genotyped. Distributions of SDMA and ADMA were skewed, hence comparisons across the gene polymorphisms were performed using Kruskal-Wallis tests, and summarized using medians and interquartile ranges. Univariable analysis did not demonstrate a significant difference in the levels of SDMA or ADMA amongst the different genotypic groups of either rs37369AGXT2 (p = 0.800, 0.977) or rs28305AGXT2 (p = 0.463, 0.634). In multivariable analyses, ADMA levels were found to be significantly associated with erythrocyte sedimentation rate and estimated glomerular filtration rate, whilst SDMA levels were significantly associated with estimated glomerular filtration rate and quantitative insulin sensitivity check index. After adjustments for these factors, the relationship between the AGXT2 gene variants and both ADMA and SDMA remained non-significant. Our study in a well-characterized RA population did not show an association between serum concentrations of dimethylarginines and genetic variants of the AGXT2 gene.

Endothelial injury in rheumatoid arthritis: a crosstalk between dimethylarginines and systemic inflammation.

BACKGROUND: Symmetric (SDMA) and asymmetric (ADMA) dimethylarginines have emerged as novel biomarkers of cardiovascular disease (CVD) in several disease settings associated with atherosclerosis. Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease characterized by high CVD mortality and morbidity. ADMA and SDMA levels are abnormal in RA patients, but their correlation with assessments of endothelial function and structure remains unknown. We aimed to investigate whether SDMA and ADMA are associated with carotid intima media thickness (cIMT) and arterial stiffness as well as non-invasive assessments of in vivo micro- and macrovascular endothelial function in RA patients with high systemic inflammatory load. METHOD: ADMA and SDMA levels were measured using immunoassays in 197 RA individuals. Twenty-six of these [23 (86.4%) females, median age 70, quartiles (60, 73)] were identified as having high inflammatory markers [erythrocyte sedimentation rate (ESR) >25 mm/hr and C-reactive protein (CRP) > 5 mg/L], and were compared to the remainder of the cohort. Patients underwent assessments of microvascular endothelium-dependent and endothelium-independent function [laser Doppler imaging with iontophoresis of acetylcholine (Ach) and sodium-nitroprusside (SNP) respectively], macrovascular endothelium-dependent and endothelium-independent function (flow-mediated dilatation and glyceryl-trinitrate-mediated dilation respectively), and vascular morphology [pulse wave analysis, and carotid intima media thickness (cIMT)]. RESULTS: Significant interactions with inflammation were detected in the associations between ACh and both SDMA (p = 0.014) and ADMA:SDMA ratio (p = 0.027), as well as between SNP and SDMA (p = 0.042) and between arterial stiffness and ADMA:SDMA (p = 0.036), with the associations being stronger in the patients with high inflammatory markers in each case. CONCLUSIONS: Besides their emerging role as markers of endothelial dysfunction SDMA and ADMA may promote endothelial injury in RA as mediators of the adverse effects of systemic inflammation on micro- and macrovasculature respectively in patients with active disease.

In vivo microvascular and macrovascular endothelial function is not associated with circulating dimethylarginines in patients with rheumatoid arthritis: a prospective analysis of the DRACCO cohort.

OBJECTIVES: To examine associations between asymmetric (ADMA), symmetric dimethylarginine (SDMA) and ADMA:SDMA ratio with assessments of endothelial function and coronary artery perfusion in RA patients. METHODS: ADMA and SDMA levels were measured in 197 RA individuals [144 (77.4%) females, median age: 66 years (quartiles: 59-73)]. Patients underwent assessments of microvascular endothelium-dependent and endothelium-independent function, macrovascular endothelium-dependent and endothelium-independent function and vascular morphology (pulse wave analysis, carotid intima-media thickness (cIMT), and carotid plaque). Coronary perfusion was assessed by subendocardial viability ratio (SEVR). RESULTS: SEVR correlated with SDMA (r = 0.172, p = 0.026) and ADMA:SDMA (r = -0.160, p = 0.041) in univariable analysis, but not in multivariable analysis accounting for confounding factors. Neither ADMA:SDMA ratio nor SDMA were significantly correlated with microvascular or macrovascular endothelial function, or with arterial stiffness and cIMT. Within subgroup of patients (n = 26) with high inflammatory markers, a post-hoc analysis showed that SDMA and the ADMA:SDMA ratio were significantly associated with endothelium-dependent microvascular function in univariable analysis, with Pearson's r correlation coefficients of -0.440 (p = 0.031) and 0.511 (p = 0.011), respectively. Similar finding were established between ADMA:SDMA ratio and arterial stiffness in univariable analysis, with Pearson's r of 0.493, (p = 0.024). CONCLUSION: Dimethylarginines were not found to be significantly associated with several assessments of vascular function and morphology in patients with RA, however, post-hoc analysis indicates that there may be associations in patients with raised inflammatory markers. Our results suggest that dysregulated NO metabolism may not be the sole mechanism for the development of preclinical atherosclerosis in RA.

Symmetric Dimethylarginine Is Not Associated with Cumulative Inflammatory Load or Classical Cardiovascular Risk Factors in Rheumatoid Arthritis: A 6-Year Follow-Up Study.

Symmetric dimethylarginine (SDMA) indirectly inhibits nitric oxide (NO) synthesis and predicts cardiovascular and all-cause mortality in high-risk patients. The aim of our study was to investigate the associations of cumulative inflammatory burden (assessed by serial measurements of inflammatory markers) and classical cardiovascular (CV) disease risk factors with SDMA in RA patients. 201 RA patients (155 females, median age 67 (59-73)) were assessed at baseline (2006). Classical CV disease risk factors were recorded and systemic inflammation was determined by the measurement of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). At follow-up (2012) SDMA levels were measured by enzyme-linked immunosorbent assay. Mean SDMA levels in RA population were 0.40 (0.40-0.53) µmol/L. No significant association between SDMA and cumulative inflammatory load was established in the analysis. SDMA levels were not found to be significantly related to CV disease risk factors. We explored the potential relationship between SDMA and cumulative inflammatory burden in patients with RA and obtained negative results. SDMA did not relate to CV disease risk factors in our population and its clinical significance as a surrogate marker of endothelial dysfunction in patients with RA remains to be determined.

Breast cancer therapy and cardiovascular risk: focus on trastuzumab.

Breast cancer is the most common cancer in the UK. Advances in the methods of early diagnosis as well as newer and more effective treatments have led to improvements of disease-free and overall survival over the last decade. Almost one-third of breast cancers present with an aggressive form characterized by increased expression of human epidermal growth receptor 2 (HER2) proteins. A targeted treatment using monoclonal antibodies against HER2 expression such as trastuzumab has been shown to improve survival. Unfortunately, there is a degree of cardiotoxicity associated with these agents, as inhibition of HER2 pathways can also impair cardioprotective pathways. In the present review, we discuss the mechanisms by which trastuzumab might affect vascular homeostasis leading to endothelial dysfunction. We also provide suggestions for future research examining the effects of trastuzumab on the vasculature in breast cancer.

A methodological approach to non-invasive assessments of vascular function and morphology.

The endothelium is the innermost lining of the vasculature and is involved in the maintenance of vascular homeostasis. Damage to the endothelium may predispose the vessel to atherosclerosis and increase the risk for cardiovascular disease. Assessments of peripheral endothelial function are good indicators of early abnormalities in the vascular wall and correlate well with assessments of coronary endothelial function. The present manuscript details the important methodological steps necessary for the assessment of microvascular endothelial function using laser Doppler imaging with iontophoresis, large vessel endothelial function using flow-mediated dilatation, and carotid atherosclerosis using carotid artery ultrasound. A discussion on the methodological considerations for each of the techniques is also presented, and recommendations are made for future research.

Symmetric dimethylarginine (SDMA) serum levels in rheumatoid arthritis: correlations with insulin resistance and disease activity scores.

Vascular abnormalities predisposing to atherosclerosis are present in patients with rheumatoid arthritis (RA) and associate with excess cardiovascular risk. Symmetric dimethylarginine (SDMA), an endogenous inhibitor of nitric oxide (NO) synthase activity, has been recognised as novel risk factor for endothelial dysfunction and cardiovascular disease. We aimed to compare SDMA levels in RA patients and controls and to investigate whether they are influenced by demographic, inflammatory or metabolic factors. Serum SDMA levels were measured in 197 RA individuals [median age: 67 years (quartiles: 59-3), 153 (78 %) females] and 82 controls [median age: 44 years [quartiles: 33-55, 50 (61 %) females]. Routine biochemistry tests, lipid profile, glycemic profile [glucose, insulin, homeostasis model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI)], as well as inflammatory markers were measured in all patients. Paired analysis was employed for the comparison of SDMA in two groups and multivariable regression models were performed to identify predictors of SDMA in the RA cohort. SDMA was significantly lower in RA than control patients in both unpaired and paired analyses (P < 0.001 and P = 0.005, respectively), with the magnitude of the difference being similar in both models. QUICKI (P = 0.005) and disease activity score-28 (P = 0.007) were positively related to SDMA in the RA cohort, whilst a negative correlation with renal function (eGFR) was detected (P = 0.005). The molecular explanation of lower serum SDMA is unclear, but the established relationships with indices of disease activity and insulin resistance, may underline the pathogenetic role of the L-arginine/NO pathway dysregulation in the development of atherosclerosis in RA. The biological and clinical importance of SDMA in RA remains to be evaluated in clinical and experimental studies.