Methylated arginines in stable and acute patients with coronary artery disease before and after percutaneous revascularization

International Journal of Cardiology 129 (2008) 288 – 291 www.elsevier.com/locate/ijcard

Letter to the Editor

Methylated arginines in stable and acute patients with coronary artery disease before and after percutaneous revascularization Ole Frøbert a,b,⁎, Søren P. Hjortshøj a , Ulf Simonsen b , Jan Ravkilde c a

Department of Cardiology, Center for Cardiovascular Research, Aalborg Hospital, Aarhus University Hospital, Denmark b Department of Pharmacology, University of Aarhus, Denmark c Department of Cardiology, Skejby Hospital, Aarhus University Hospital, Denmark Received 21 February 2007; accepted 26 April 2007 Available online 8 August 2007

Abstract Background: Impairment of the nitric oxide synthase (NOS) pathway independently predicts cardiovascular events. We investigated whether plasma levels of the NOS inhibitor asymmetric dimethylarginine (ADMA), of symmetric dimethylarginine (SDMA) and of the nitrogen oxide substrate L-arginine can serve as additional staging biomarkers in stable coronary artery disease, non-ST-segment myocardial infarction (NSTEMI) and ST-segment myocardial infarction (STEMI). Materials and methods: Consecutive patients referred for percutaneous coronary intervention (PCI) were studied. Peripheral blood samples were drawn immediately before, immediately after and 24 h following PCI and analyzed by means of high-performance liquid chromatography. Results: Seventy-four patients were studied: 27 patients with stable angina pectoris (7 women, 61.4 ± 1.9 years), 23 NSTEMI patients (9 women, 61.8 ± 2.3 years) and 24 STEMI patients (7 women, 61.3 ± 2.8 years). Plasma concentrations of ADMA and SDMA were elevated following PCI compared to before PCI but there were no differences in concentrations between STEMI, NSTEMI and stable angina patients. Plasma concentrations of L-arginine rose after PCI but remained lower in patients with STEMI than in those with NSTEMI or in stable angina patients. Medication might influence L-arginine concentrations and the use of HMG CoA reductase inhibitors and β-adrenoceptor antagonists at study inclusion was significantly less common in STEMI patients compared to NSTEMI and stable angina patients. Conclusion: L-arginine levels were lower in patients with STEMI and we found changes in ADMA levels over shorter time periods than previously considered possible. We speculate that these variations may be related to the natural history of myocardial infarction or to periprocedural stress related to PCI. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Coronary artery; Endothelium; Ischemic heart disease; Myocardial markers

1. Introduction Impairment of the nitric oxide synthase (NOS) pathway independently predicts cardiovascular events [1]. Asymmetric dimethylarginine (ADMA) is the major NOS inhibitor [2] and a strong predictor of cardiovascular events [3–6] whereas symmetric dimethylarginine (SDMA) competes with ⁎ Corresponding author. Department of Cardiology, Center for Cardiovascular Research, Aalborg Hospital, Aarhus University Hospital, DK-9000 Aalborg, Denmark. Tel.: +45 99 32 22 12; fax: +45 99 32 23 61. E-mail address: [email protected] (O. Frøbert). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.04.152

the nitric oxide (NO) precursor L-arginine for uptake into cells. L-arginine is the major substrate for NO and a partial deficiency of L-arginine may exist in patients with severe ischemic heart disease [7]. It remains unknown whether plasma levels of methylated arginines might differ dependent on the acuteness of coronary artery disease. Furthermore, it is uncertain if plasma levels of methylated arginines vary significantly over short time periods [2]. We investigated if plasma levels of ADMA, SDMA and L-arginine can serve as additional staging biomarkers in three different settings of cardiovascular disease: stable coronary artery disease, non-ST-segment myocardial

O. Frøbert et al. / International Journal of Cardiology 129 (2008) 288–291

infarction (NSTEMI) and ST-segment myocardial infarction (STEMI).

Table 1 Baseline data

2. Materials and methods We assessed blood samples immediately before, immediately after, and 24 h following successful percutaneous coronary intervention (PCI). All participants gave informed consent before the invasive procedure and the protocol was approved by the local ethical committee. Concentrations of L-arginine, ADMA and SDMA were assessed by high-performance liquid chromatography and precolumn derivation with o-pthaldialdehyde (OPA) according to previous studies [8,9]. All data are presented as mean ± SEM. Comparisons between groups were made with a one-way analysis of variance and in case of statistical significance a Tukey post hoc test was applied. Comparisons within groups were made with a oneway repeated measures analysis of variance and a Dunnett's post hoc test. The significance of differences in proportions was tested with the χ2 statistic. Bivariate associations were examined by least square linear regression. Differences were considered statistically significant when P b 0.05. 3. Results Baseline characteristics for the 74 patients in the three groups are listed in Table 1. The patients with stable angina pectoris were in CCS-class 1–3 (mean 1.8 ± 0.1). At study inclusion HMG CoA reductase inhibitor (statin) use and β-adrenoceptor antagonist use were significantly less frequent in STEMI patients compared to NSTEMI and stable angina patients. ADMA and SDMA did not differ between groups while ADMA, SDMA and L-arginine concentrations increased following PCI (Fig. 1). In the STEMI group, L-arginine concentrations were significantly lower at all three time points compared to the stable angina group and to the NSTEMI group. Levels of ADMA, SDMA or L-arginine did not correlate with levels of TnT, TnI or hsCRP. There was no statistically significant relation between Thrombolysis in Myocardial Infarction (TIMI) flow grade before intervention and methylated arginines across groups. There were no significant differences between ADMA levels in non-smokers (0.58 ± 0.04 μmol/l, n = 12), ex-smokers (0.54 ± 0.02 μmol/l, n = 35) and current smokers (0.55 ± 0.03 μmol/l, n = 21) (P = 0.59, smoking habits were unknown for six subjects). 4. Discussion We found that patients with STEMI had lower levels of than other patient categories with coronary artery disease. The differences can be explained by reduced L-arginine synthesis or increased breakdown. Arginine metabolism is highly complex and involves multiple pathways and tissues [10] and excretion is mainly renal [11]. However, renal function did not differ between our patient groups. L-arginine L-arginine

289

Clinical characteristics Age, mean (SEM), y Sex, male/female, n Weight, mean (SEM) Systolic blood pressure (mm Hg) Diastolic blood pressure (mm Hg) Hypertension, n (%) Diabetes, n (%) Duration from symptom onset to PCI (hours) Medication prior to invasive procedure β-Blockers, n (%) Calcium antagonists, n (%) ACE-inhibitors or AII antagonists, n (%) HMG CoA reductase inhibitors, n (%) Biochemical variables Creatinine, mean (SEM), μmol/l Total cholesterol, mean (SEM), mmol/l Triglyceride, mean (SEM), mmol/l HDL cholesterol, mean (SEM), mmol/l LDL cholesterol, mean (SEM), mmol/l

Stable angina (n = 27)

NSTEMI (n = 23)

STEMI (n = 24)

Pvalue

61.4 (1.9) 20/7 76(3) 139 (4)

61.8 (2.3) 14/9 79 (4) 126 (3)

61.3 (2.8) 17/7 81 (3) 132 (5)

0.99 0.59 0.64 0.09

80 (2)

72 (2)⁎

81 (3)

0.01

17 (63) 2 (7) –

10 (44) 2 (9) 199 (26)

9 (38) 1 (4) 5.1 (1.1)

0.23 0.81 –

18 (67) 11 (41)

20 (87) 4 (17)

4 (17) ⁎ 5 (21)

b0.001 0.13

9 (33)

13 (55)

9 (37)

0.24

20 (74)

17 (74)

2 (8) ⁎

b0.001

91 (2)

91 (4)

95 (4)

0.63

5.1 (0.2)

4.8 (0.5)

5.7 (0.3)

0.12

1.5 (0.5)

1.5 (0.4)

1.9 (0.3)

0.62

1.4 (0.1)

1.1 (0.1)⁎

1.4 (0.1)

0.04

3.1 (0.2)

2.7 (0.4)

3.0 (0.3)

0.98

Values are mean and (SEM). Differences were tested by one-way ANOVA (P-value) and a Tukey post hoc test (asterisk indicates differences compared with the other two groups). Data on lipid profiles were incomplete. Blood samples were obtained from 7 patients with stable angina, 11 with NSTEMI and 21 with STEMI.

concentration might increase during lipid-lowering therapy [12] and β-adrenoceptor antagonists dose-dependently block splenic arginase activity which metabolizes L-arginine [13]. Thus, the infrequent use of statins and β-adrenoceptor antagonists in STEMI patients could have contributed to the lower levels in these patients. With L-arginine being the major substrate for NO another intriguing explanation of reduced concentrations in STEMI patients is the possibility that L-arginine is linked to the occurrence of myocardial infarction. This is supported by findings in hypercholesterolemic stroke-prone spontaneously hypertensive rats suggesting that NO deficiency induces myocardial infarction [14] and by another study in spontaneously hypertensive rats demonstrating a decrease in plasma L-arginine concentration following acute reduction in blood pressure [15]. In a human study of the vasodilatory response to coronary L-arginine infusion, dilation was more pronounced in complex stenoses than smooth stenoses in agreement with local deficiency of L-arginine at locations prone to myocardial

290

O. Frøbert et al. / International Journal of Cardiology 129 (2008) 288–291

Fig. 1. ADMA (top), SDMA (middle) and L-arginine (bottom) concentrations in 27 patients with stable angina pectoris, 23 patients with non-ST segment myocardial infarction (NSTEMI) and 24 patients with ST segment myocardial infarction (STEMI). Blood samples were drawn immediately before (black), immediately after (grey) and 24 h (dark grey) following PCI. ADMA increased in all groups but there were no between-group differences. ⁎), ⁎⁎) and ⁎⁎⁎) denote P b 0.05, P b 0.01 and P b 0.001 compared to before PCI. §) and §§) denote P b 0.05 and P b 0.01 compared to stable angina patients. #), ##) and ###) denote P b 0.05, P b 0.01 and P b 0.001 compared to NSTEMI patients.

infarction [7]. We speculate if the finding of reduced L-arginine levels in STEMI patients might reflect arginine consumption by the NOS pathway or could be explained by augmented arginine catabolism by increased utilization of arginine in the arginase and NO pathways. Asymmetric dimethylarginine (ADMA) is the major endogenous NOS inhibitor. ADMA is formed by protein argi-

nine N-methyltransferases (PRMTs) which are upregulated by LDL cholesterol [16]. ADMA is independently related to and interact with several other risk factors and may be an endogenous proatherogenic molecule. Elevated plasma ADMA levels are prevalent in patients with hypercholesterolemia [17,18], ADMA increases endothelial oxidative stress and potentiates monocyte binding [19] and elevated ADMA

O. Frøbert et al. / International Journal of Cardiology 129 (2008) 288–291

concentration increases the risk of acute cardiovascular events [3–6]. It has previously been put forward that it is unlikely that ADMA plasma levels vary significantly over short time periods [2]. Nevertheless, in all groups in the present study we could demonstrate an increase in ADMA-concentration from before to after the PCI. The transient ischemic cellular stress associated with PCI [20] could have enhanced protein turnover [21] and this could serve as an explanation for the ADMA rise after PCI. Dimethylarginine dimethylaminohydrolases (DDAHs) metabolize more than 90% of ADMA and are found in various organs including kidney and vascular walls [21] and DDAH activity is impaired by oxidative stress [1]. Symmetric dimethylarginine (SDMA) is not an inhibitor of NOS and is considered a less biologically active arginine analogue. Similar to ADMA, SDMA also rose during PCI in STEMI and NSTEMI patients. Because of this similarity and because DDAH has no activity towards SDMA [21] we find it unlikely that DDAHs played a significant role in the ADMA increase during PCI. We speculate that the variations in L-arginine and ADMA may be related to the natural history of myocardial infarction or to peri-procedural stress related to PCI. Acknowledgements The study was supported by the Danish Heart Foundation, the Danish Medical Research Council and Hørslev Fonden. We thank Karen K. Busch for expert analyses of arginines. References [1] Cooke JP. Asymmetrical dimethylarginine: the Uber marker? Circulation 2004;109:1813–8. [2] Vallance P, Leiper J. Cardiovascular biology of the asymmetric dimethylarginine: dimethylarginine dimethylaminohydrolase pathway. Arterioscler Thromb Vasc Biol 2004;24:1023–30. [3] Valkonen VP, Paiva H, Salonen JT, et al. Risk of acute coronary events and serum concentration of asymmetrical dimethylarginine. Lancet 2001;358:2127–8. [4] Schnabel R, Blankenberg S, Lubos E, et al. Asymmetric dimethylarginine and the risk of cardiovascular events and death in patients with coronary artery disease: results from the AtheroGene Study. Circ Res 2005;97:e53–9. [5] Krempl TK, Maas R, Sydow K, Meinertz T, Boger RH, Kahler J. Elevation of asymmetric dimethylarginine in patients with unstable angina and recurrent cardiovascular events. Eur Heart J 2005;26:1846–51.

291

[6] Lu TM, Ding YA, Lin SJ, Lee WS, Tai HC. Plasma levels of asymmetrical dimethylarginine and adverse cardiovascular events after percutaneous coronary intervention. Eur Heart J 2003;24:1912–9. [7] Tousoulis D, Davies GJ, Tentolouris C, Goumas G, Stefanadis C, Toutouzas P. Vasomotor effects of D- and L-arginine in stenotic atheromatous coronary plaque. Heart 2001;86:296–301. [8] Boger RH, Bode-Boger SM, Szuba A, et al. Asymmetric dimethylarginine (ADMA): a novel risk factor for endothelial dysfunction: its role in hypercholesterolemia. Circulation 1998;98:1842–7. [9] Martinez AC, Stankevicius E, Jakobsen P, Simonsen U. Blunted nonnitric oxide vasodilatory neurotransmission in penile arteries from renal hypertensive rats. Vascul Pharmacol 2006;44:354–62. [10] Wu G, Morris Jr SM. Arginine metabolism: nitric oxide and beyond. Biochem J 1998;336(Pt 1):1–17. [11] Dhanakoti SN, Brosnan JT, Herzberg GR, Brosnan ME. Renal arginine synthesis: studies in vitro and in vivo. Am J Physiol 1990;259:E437–42. [12] Dierkes J, Westphal S, Martens-Lobenhoffer J, Luley C, Bode-Boger SM. Fenofibrate increases the L-arginine:ADMA ratio by increase of Larginine concentration but has no effect on ADMA concentration. Atherosclerosis 2004;173:239–44. [13] Bernard AC, Fitzpatrick EA, Maley ME, et al. Beta adrenoceptor regulation of macrophage arginase activity. Surgery 2000;127:412–8. [14] Ikeda K, Nara Y, Tagami M, Yamori Y. Nitric oxide deficiency induces myocardial infarction in hypercholesterolaemic stroke-prone spontaneously hypertensive rats. Clin Exp Pharmacol Physiol 1997;24:344–8. [15] Prados P, Matsunaga H, Mori T, et al. Changes of plasma L-arginine levels in spontaneously hypertensive rats under induced hypotension. Biomed Chromatogr 1999;13:27–32. [16] Boger RH, Sydow K, Borlak J, et al. LDL cholesterol upregulates synthesis of asymmetrical dimethylarginine in human endothelial cells: involvement of S-adenosylmethionine-dependent methyltransferases. Circ Res 2000;87:99–105. [17] Pereira EC, Bertolami MC, Faludi AA, Salem M, Bersch D, Abdalla DS. Effects of simvastatin and L-arginine on vasodilation, nitric oxide metabolites and endogenous NOS inhibitors in hypercholesterolemic subjects. Free Radic Res 2003;37:529–36. [18] Eid HM, Eritsland J, Larsen J, Arnesen H, Seljeflot I. Increased levels of asymmetric dimethylarginine in populations at risk for atherosclerotic disease. Effects of pravastatin. Atherosclerosis 2003;166:279–84. [19] Boger RH, Bode-Boger SM, Tsao PS, Lin PS, Chan JR, Cooke JP. An endogenous inhibitor of nitric oxide synthase regulates endothelial adhesiveness for monocytes. J Am Coll Cardiol 2000;36:2287–95. [20] Iuliano L, Pratico D, Greco C, et al. Angioplasty increases coronary sinus F2-isoprostane formation: evidence for in vivo oxidative stress during PTCA. J Am Coll Cardiol 2001;37:76–80. [21] Leiper JM, Vallance P. The synthesis and metabolism of asymmetric dimethylarginine (ADMA). Eur J Clin Pharmacol 2006;62(Suppl 13): 33–8.