- Email: [email protected]
Relationship of asymmetric dimethylarginine (ADMA) with extent and functional severity of coronary atherosclerosis
International Journal of Cardiology 220 (2016) 629–633
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Relationship of asymmetric dimethylarginine (ADMA) with extent and functional severity of coronary atherosclerosis Fabio Mangiacapra a,b, Micaela Conte a, Chiara Demartini b, Olivier Muller a, Leen Delrue a, Karen Dierickx a, Germano Di Sciascio b, Bruno Trimarco c, Bernard De Bruyne a, William Wijns a, Jozef Bartunek a, Emanuele Barbato a,c,⁎ a b c
Cardiovascular Center Aalst, OLV Clinic, Aalst, Belgium Department of Cardiovascular Sciences, Campus Bio-Medico University, Rome, Italy Division of Cardiology, Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy
a r t i c l e
i n f o
Article history: Received 21 March 2016 Received in revised form 16 June 2016 Accepted 27 June 2016 Available online 28 June 2016 Keywords: Asymmetric dimethylarginine Coronary atherosclerosis Fractional flow reserve
a b s t r a c t Background: Elevated serum levels of asymmetric dimethylarginine (ADMA) are associated with endothelial dysfunction and atherogenesis. In patients with suspected coronary artery disease (CAD), we assessed the correlation of serum ADMA levels with extent and functional significance of coronary atherosclerosis. Methods: We enrolled 281 patients with suspected CAD undergoing coronary angiogram. Angiographic CAD severity was evaluated by Bogaty score. In patients with angiographic evidence of at least one intermediate coronary stenosis (≥50% diameter stenosis), functional significance was assessed by fractional flow reserve (FFR). Blood samples were collected in all patients prior to coronary angiography for measurement of serum ADMA levels. Results: We observed across tertiles of ADMA levels increasingly higher values of both Stenosis Score (2.25 ± 1.70 vs. 2.89 ± 1.99 vs. 2.95 ± 1.82, p = 0.016) and Extent Index (0.52 ± 0.32 vs. 0.61 ± 0.39 vs. 0.72 ± 0.47, p = 0.003). The association between ADMA levels and Extent Index remained significant after multivariate adjustment (p = 0.005). Patients with FFR ≤0.80 in at least one vessel (n = 113) had significantly higher ADMA levels compared with patients without functionally significant CAD (0.51 [0.43–0.64] vs. 0.46 [0.39–0.58] μmol/L, p = 0.005). Serum ADMA levels were independent predictors of abnormal FFR after adjustment for extent score (odds ratio 7.35, 95% confidence interval 1.05–56.76, p = 0.046). Conclusions: Serum ADMA levels are independent predictors of coronary atherosclerosis extent and functional significance of CAD. © 2016 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide synthase (NOS), and increased ADMA levels have been linked to endothelial dysfunction [1–3]. ADMA levels have been correlated with the presence of peripheral atherosclerosis [1,4,5], and the occurrence of adverse cardiovascular events in different clinical settings [2, 6–11], including in patients with coronary artery disease (CAD) [12]. However, inconsistent results regarding the association between ADMA levels and the extent and severity of CAD have been reported. On one side, ADMA levels have been associated with increased coronary atherosclerosis and independently predicted CAD [11,13–16]. In other studies this finding was either not confirmed after multivariate adjustment [8, 17], or not found at all [18]. These discrepancies might be the consequence of several definitions of CAD and different methods used to ⁎ Corresponding author at: Cardiovascular Center Aalst, OLV Clinic, Moorselbaan 164, B9300 Aalst, Belgium. E-mail address: [email protected] (E. Barbato).
http://dx.doi.org/10.1016/j.ijcard.2016.06.254 0167-5273/© 2016 Elsevier Ireland Ltd. All rights reserved.
evaluate its extent and severity. Invasive functional assessment of coronary atherosclerosis severity by fractional flow reserve (FFR) is being increasingly used to target patients requiring coronary revascularization [19,20]. In fact, functional significance of CAD is a strong determinant of poor prognosis [21], and coronary revascularization when guided by FFR is associated with improved clinical outcomes [22–25]. Functional coronary stenosis severity assessed by FFR correlates with biomarkers of lipid modification [26] and inflammation [27]. In the present study we assessed the correlation of serum ADMA levels with the presence, extent and functional severity of coronary atherosclerosis as assessed by FFR in patients referred to coronary angiography. 2. Methods 2.1. Study population Consecutive patients older than 18 years with suspected stable CAD undergoing elective coronary angiography at Cardiovascular Center Aalst from March 2010 to February 2011 were considered for recruitment in the present study. Patients were excluded in case of: unstable angina, previous acute coronary syndrome, previous myocardial
630
F. Mangiacapra et al. / International Journal of Cardiology 220 (2016) 629–633
Table 1 Demographic and clinical characteristics. Total population
Male, n (%) Age, years BMI, kg/m2 Hypertension, n (%) Dyslipidemia, n (%) Diabetes mellitus, n (%) Smoking, n (%) Family history, n (%) eGFR (ml/min/1.73 m2) eGFR b 60 ml/min/1.73 m2, n (%) C reactive protein, mg/l LV ejection fraction, % LV end-diastolic pressure, mmHg LV end-diastolic volume, ml LV end-systolic volume, ml Medical therapy, n (%) Aspirin ACE inhibitors Angiotensin receptor blockers Beta blockers Calcium channel blockers Nitrates Statins
ADMA Tertiles
p value
Low
Medium
High
184 66 ± 12 27 ± 4 160 188 73 31 73 75 ± 20 58 (21) 1.58 [0.72–4.22] 69 ± 14 17 ± 7 148 ± 50 48 ± 34
62 (66) 65 ± 11 27 ± 5 49 (52) 60 (64) 21 (22) 15 (15) 25 (27) 78 ± 18 14 (15) 1.22 [0.71–2.99] 74 ± 12 15 ± 7 152 ± 56 42 ± 35
62 (66) 68 ± 12 27 ± 4 58 (62) 66 (70) 24 (26) 7 (7) 19 (20) 74 ± 21 20 (21) 1.90 [0.96–4.98] 68 ± 13 16 ± 7 148 ± 50 45 ± 26
60 (65) 66 ± 12 27 ± 5 53 (57) 62 (67) 28 (30) 9 (10) 29 (31) 72 ± 21 24 (26) 1.60 [0.74–4.02] 65 ± 15 19 ± 7 143 ± 42 57 ± 38
221 (79) 101 (36) 22 (8) 161 (57) 48 (17) 62 (22) 179 (64)
76 (81) 27 (29) 10 (11) 48 (51) 14 (15) 18 (19) 55 (59)
69 (73) 40 (43) 6 (6) 54 (57) 14 (15) 19 (20) 63 (67)
76 (82) 34 (37) 6 (6) 59 (63) 20 (22) 25 (27) 61 (66)
p value Low vs. High
0.972 0.112 0.465 0.415 0.868 0.477 0.155 0.228 0.078 0.180 0.219 b0.001 0.003 0.467 0.014
0.836 0.600 0.670 0.446 0.684 0.227 0.199 0.489 0.026 0.064 0.224 0.002 0.001 0.217 0.010
0.311 0.140 0.462 0.231 0.383 0.385 0.430
0.879 0.253 0.306 0.087 0.241 0.209 0.318
eGFR = estimated glomerular filtration rate; LV = left ventricle; ACE = angiotensin converting enzyme. revascularization, left ventricle ejection fraction b30%, severe valvular heart disease, endstage renal disease (estimated glomerular filtration rate b 15 ml/min/1.73 m2). In all patients traditional cardiovascular risk factors and medications taken on admission were recorded. The local Ethics Committee approved the study and all patients gave informed consent.
2.2. Coronary angiography and functional evaluation of CAD Coronary angiography was performed according to standard practice. Coronary stenosis was defined as a ≥50% by visual estimation in at least one major vessel. Angiographic analyses included the evaluation of angiographic CAD severity and extent by the Bogaty score [28]. Angiographic severity of disease (Stenosis Score) refers to the total number of ≥50% narrowings in all vessels of the angiogram. A maximum of three stenoses were permitted per coronary arterial segment. Extent of coronary disease (Extent Index) was obtained by dividing the extent score of the entire coronary arterial tree by the number of analyzed segments. A segment was scored 0 if it was angiographically normal, 1 if ≤10% of its length appeared abnormal, 2 if N10% up to 50% of its length was abnormal, and 3 if N50% of its length was abnormal. A total of 15 segments were considered, and therefore the Extent Index could range from 0 to 3. All angiographic analyses were performed by two independent operators (FM and MC), and discordances were resolved by consensus. In the presence of at least one coronary stenosis ≥50%, functional severity of CAD was assessed by measuring FFR [29]. A 6 French guide catheter was used to intubate coronary ostia and an intracoronary pressure/temperature sensor-tipped guidewire (PressureWire Certus, RADI, St Jude Medical, Uppsala, Sweden) was used to measure distal coronary pressure. FFR was calculated from the ratio of distal coronary pressure (Pd) to proximal coronary pressure (Pa) at maximal hyperemia. An FFR ≤0.80 was considered abnormal, identifying functionally significant coronary stenosis.
2.3. ADMA assessment A blood sample was obtained in all patients immediately before coronary angiography for determination of serum ADMA levels. ADMA levels were measured according to the manufacturer's instructions by a commercially available enzyme-linked immunosorbent assay (DLD Diagnostika GmbH., Hamburg, Germany), previously validated against highperformance liquid chromatography coupled to mass spectrometry, the golden standard for ADMA determinations [30]. Briefly, aliquots (50 μl) of pretreated standards, controls and samples were pipetted into the wells of the coated microtiter plate and 50 μl antiserum solution was added into all wells. The plate was incubated overnight at 2–8 °C and washed four times with wash buffer. Subsequently, 100 μl enzyme conjugate was added to each well and the microtiter plate was incubated for 1 h at room temperature. The wells were again washed four times. Substrate solution (100 μl) was added to the wells and the plate was incubated for 20 to 30 min at room temperature. Finally, the reaction was stopped with stop solution and optical density was read at 450 nm using a microplate photometer. Samples were measured in duplicate and the mean absorbance value was used to determine the ADMA concentration based on the standard curve. Data was presented as μmol/L. 2.4. Statistics Continuous variables are expressed as mean ± SD, or median [interquartile range]. Categorical variables are reported as frequencies and percentages. Normality of continuous variable distribution was tested with the Shapiro–Wilk test. One-way analysis of variance or Kruskall-Wallis test was used to compare continuous variables between tertiles of ACEF score. Comparisons between categorical variables were evaluated using Pearson χ2 test. Adjustments for repeated measures were performed when appropriate. Linear regression analysis was used to assess predictors of CAD extent (Extent Index). All variables with a significant (b0.05) univariate association with the outcome measure were included in the final multivariate model. The ability of ADMA levels to discriminate between patients with and without myocardial ischemia was assessed by receiver operating characteristic curves and associated area under the curve (AUC). The optimal cutoff point of ADMA score to discriminate between patients with and without myocardial ischemia was calculated by determining the value that provided the greatest sum of sensitivity and specificity. All statistical analyses were performed using STATA/IC 12 (STATA Corp., College Station, Texas) and a p value b0.05 was considered statistically significant.
3. Results
Fig. 1. Asymmetric dimethylarginine (ADMA) levels and the presence of coronary artery disease. Distribution of patients according to the number of vessels with at least one ≥50% stenosis in ADMA tertiles.
A total of 281 patients were enrolled. Median levels of ADMA were 0.483 μmol/L, ranging from 0.207 to 1.122 μmol/L. Clinical characteristics in the overall population and according to ADMA tertiles are reported in Table 1. Risk factors for CAD and medical therapy were not significantly different across ADMA tertiles, whereas renal function and left ventricular indices were significantly worse in patients with higher ADMA levels.
F. Mangiacapra et al. / International Journal of Cardiology 220 (2016) 629–633
631
Fig. 2. Asymmetric dimethylarginine (ADMA) levels and the extent of coronary artery disease. Stenosis Score (Panel A) and Extent Index (Panel B) values in ADMA tertiles.
At coronary angiography, 45 (16%) patients presented normal coronary arteries. At least one coronary stenosis (≥50%) was found in 1 vessel in 125 (44%) patients, in 2 vessels in 69 patients (25%), and in 3 vessels in 42 (15%) patients. The number of diseased vessels progressively increased across ADMA tertiles (p for trend 0.015; Fig. 1), with patients in the higher ADMA tertile presenting the highest prevalence of multivessel disease (52% vs. 27% in the lowest tertile; p b 0.001). We observed increasing values of both Stenosis Score (2.25 ± 1.70 vs. 2.89 ± 1.99 vs. 2.95 ± 1.82, p = 0.016; Fig. 2, Panel A) and Extent Index (0.52 ± 0.32 vs. 0.61 ± 0.39 vs. 0.72 ± 0.47, p = 0.003; Fig. 2, Panel B) across tertiles of ADMA levels. The association between ADMA levels and Extent Index remained significant after multivariate adjustment (p = 0.005; Table 2). Patients with abnormal FFR (e.g. ≤0.80) in at least one vessel (n = 113) had significantly higher ADMA levels as compared with patients with FFR N 0.80 for all measured lesions (0.51 [0.43–0.64] vs. 0.46 [0.39–0.58] μmol/L, p = 0.005; Fig. 3). ADMA levels were independent predictors of abnormal FFR after adjustment for extent score (odds ratio 7.35, 95% confidence interval 1.05–56.76, p = 0.046). At ROC curve analysis, ADMA levels could significantly discriminate between patients with and without abnormal FFR, with an AUC of 0.607 (95% CI 0.535–0.679, p = 0.005). The optimal cutoff to predict the presence of abnormal FFR was an ADMA level N 0.414 μmol/L, with a sensitivity of 82% and a specificity of 36%. When the entire population was divided in four groups based on FFR values (≤0.80 or N0.80) and Extent Index (below or above the median, 0.53), we observed that those patients with FFR N 0.80 and low Extent Index presented the lowest ADMA levels (0.46 [0.40–0.55]), whereas those with abnormal FFR and high Extent Index presented the highest ADMA levels (0.52 [0.45–0.65], p = 0.015; Fig. 4).
Table 2 Univariate and multivariate predictors of coronary artery disease extent (Extent Index). Univariate model
Age Male Hypertension Diabetes mellitus Dyslipidemia Smoking Family History ACE-inhibitors Statins eGFR b 60 ml/min/1.73 m2 C Reactive Protein ADMA levels
4. Discussion Main findings of the present study are: (1) serum ADMA levels significantly correlated with the presence and extent of coronary atherosclerosis in patients undergoing elective coronary angiogram; (2) those patients with functionally significant CAD (e.g. abnormal FFR) have significantly higher ADMA levels; (3) patients with the largest atherosclerotic burden (e.g. high Extent Index) and abnormal FFR have the highest levels of serum ADMA. Several studies have demonstrated that increasing levels of ADMA are associated with higher risk of adverse cardiovascular events in different clinical settings [2,6–12]. ADMA is a well-known marker of endothelial dysfunction [1–3], and it is likely that it could contribute to an increased atherosclerotic burden. However, previous investigations exploring the association between ADMA levels and coronary atherosclerosis have reported discordant results. In patients with stable CAD, ADMA levels were higher in patients with angiographically significant stenosis (≥50% in one major coronary artery) [13], and a significant positive correlation between ADMA levels and atherosclerotic burden and extent (number of vessels with ≥50% stenosis) was observed [14,15]. In a recent study [16], higher ADMA levels correlated significantly, even after multivariate adjustment, with CAD extent evaluated with the Sullivan score, but not with the Gensini score. In subsequent studies, these observations were partly confirmed, if at all. Discrepancies have possibly derived by the adoption of different threshold values to define angiographic coronary stenosis severity (e.g. ≥20%), different score indexes (e.g. Friesinger score) [8] or by including patients with acute coronary syndromes [18]. In fact, it has been shown that patients with acute myocardial infarction have higher serum ADMA levels [9], and therefore conflicting results may be yielded when including patients with acute coronary syndromes in study assessing the relation between ADMA levels and atherosclerosis extent. Our study confirms and further extends these previous evidences. We confirmed ADMA as an independent predictor of angiographic coronary atherosclerosis extent, as assessed with the well validated Bogaty score [28]. For the first time,
Multivariate model
Standardized B
p value
Standardized B
p value
0.175 0.215 0.100 0.137 0.133 0.207 0.157 0.182 0.002 0.140 0.028 0.217
0.004 b0.001 0.102 0.025 0.030 0.001 0.010 0.425 0.922 0.026 0.665 b0.001
0.180 0.224 – 0.101 0.126 0.177 0.129 – – 0.126 – 0.164
0.004 b0.001 – 0.082 0.030 0.004 0.029 – – 0.041 – 0.005
eGFR = estimated glomerular filtration rate; ACE = angiotensin converting enzyme; ADMA = asymmetric dimethylarginine.
Fig. 3. Asymmetric dimethylarginine (ADMA) levels and abnormal FFR.
632
F. Mangiacapra et al. / International Journal of Cardiology 220 (2016) 629–633
Conflict of interest No conflicts of interest to disclose.
References
Fig. 4. Association of asymmetric dimethylarginine (ADMA) levels with abnormal FFR and coronary atherosclerosis extent. EI = Extent Index; FFR = fractional flow reserve.
we demonstrated that ADMA is higher in patients with functionally significant coronary stenosis (e.g. abnormal FFR) irrespective of the angiographic stenosis severity. ADMA levels were able to discriminate between patients with and without coronary stenoses and abnormal FFR. Though, the highest ADMA levels were observed in those patients with abnormal FFR and large atherosclerotic burden (e.g. high Extent Index). Functionally significant CAD has been demonstrated to be a strong determinant of adverse events, including mortality [31–33], and recent trials have demonstrated that functionally guided revascularization strategies (i.e. FFR guided) are able to improve clinical outcomes [22–25]. In this context, our study may provide a mechanistic explanation for the predictive clinical value of ADMA. The highest values of ADMA were in fact observed in patients with combined extensive atherosclerotic burden and functionally significant stenoses, which are at higher risk of large ischemic myocardial areas. Furthermore, the evidence of a rapid and sustained decrease in ADMA levels after percutaneous coronary revascularization [34,35] confirms the link between ADMA and underlying ischemic substrate.
4.1. Limitations This study presents several limitations. First, the sample size is relatively small. Second, coronary atherosclerosis burden was only evaluated based on angiographic parameters. Intravascular techniques (e.g. optical coherence tomography, intravascular ultrasound) could have provided more detailed information on plaque composition and distribution. Third, no serial measurements of ADMA levels were performed, and therefore we were not able to detect potential changes in ADMA concentrations in patients receiving myocardial revascularization. Fourth, we cannot provide any mechanistic explanation for the association between myocardial ischemia and elevated ADMA levels. Fifth, no data on the duration of drug therapy is available for our patients, and we cannot exclude that cardiovascular drugs may exert a timedependent effect on ADMA levels [36]. Finally, no prospective followup data on cardiovascular events are available.
5. Conclusions The results of the present study confirm the association of ADMA with the presence and extent of coronary atherosclerosis, and indicate for the first time an increase of ADMA levels in the presence of functionally significant stenoses as documented with FFR. The identification of those patients with extensive and functionally significant atherosclerotic burden might explain the increased cardiovascular risk associated with high ADMA levels.
[1] H. Miyazaki, H. Matsuoka, J.P. Cooke, et al., Endogenous nitric oxide synthase inhibitor: a novel marker of atherosclerosis, Circulation 99 (1999) 1141–1146. [2] C. Zoccali, S. Bode-Boger, F. Mallamaci, et al., Plasma concentration of asymmetrical dimethylarginine and mortality in patients with end-stage renal disease: a prospective study, Lancet 358 (2001) 2113–2117. [3] J.P. Cooke, Asymmetrical dimethylarginine: the Uber marker? Circulation 109 (2004) 1813–1818. [4] K. Furuki, H. Adachi, H. Matsuoka, et al., Plasma levels of asymmetric dimethylarginine (ADMA) are related to intima-media thickness of the carotid artery: an epidemiological study, Atherosclerosis 191 (2007) 206–210. [5] R. Maas, V. Xanthakis, J.F. Polak, et al., Association of the endogenous nitric oxide synthase inhibitor ADMA with carotid artery intimal media thickness in the Framingham Heart Study offspring cohort, Stroke 40 (2009) 2715–2719. [6] V.P. Valkonen, H. Paiva, J.T. Salonen, et al., Risk of acute coronary events and serum concentration of asymmetrical dimethylarginine, Lancet 358 (2001) 2127–2128. [7] R. Schnabel, S. Blankenberg, E. Lubos, 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. 97 (2005) e53–e59. [8] A. Meinitzer, U. Seelhorst, B. Wellnitz, et al., Asymmetrical dimethylarginine independently predicts total and cardiovascular mortality in individuals with angiographic coronary artery disease (the Ludwigshafen Risk and Cardiovascular Health study), Clin. Chem. 53 (2007) 273–283. [9] R.H. Boger, R. Maas, F. Schulze, E. Schwedhelm, Asymmetric dimethylarginine (ADMA) as a prospective marker of cardiovascular disease and mortality—an update on patient populations with a wide range of cardiovascular risk, Pharmacol. Res. 60 (2009) 481–487. [10] R.H. Boger, L.M. Sullivan, E. Schwedhelm, et al., Plasma asymmetric dimethylarginine and incidence of cardiovascular disease and death in the community, Circulation 119 (2009) 1592–1600. [11] T.M. Lu, M.Y. Chung, M.W. Lin, C.P. Hsu, S.J. Lin, Plasma asymmetric dimethylarginine predicts death and major adverse cardiovascular events in individuals referred for coronary angiography, Int. J. Cardiol. 153 (2011) 135–140. [12] T.M. Lu, Y.A. Ding, S.J. Lin, W.S. Lee, H.C. Tai, Plasma levels of asymmetrical dimethylarginine and adverse cardiovascular events after percutaneous coronary intervention, Eur. Heart J. 24 (2003) 1912–1919. [13] T.M. Lu, Y.A. Ding, M.J. Charng, S.J. Lin, Asymmetrical dimethylarginine: a novel risk factor for coronary artery disease, Clin. Cardiol. 26 (2003) 458–464. [14] T. Thum, D. Tsikas, S. Stein, et al., Suppression of endothelial progenitor cells in human coronary artery disease by the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine, J. Am. Coll. Cardiol. 46 (2005) 1693–1701. [15] F. Schulze, H. Lenzen, C. Hanefeld, et al., Asymmetric dimethylarginine is an independent risk factor for coronary heart disease: results from the multicenter Coronary Artery Risk Determination investigating the Influence of ADMA Concentration (CARDIAC) study, Am. Heart J. 152 (2006) 493, e1–493.e8. [16] O. Kruszelnicka, A. Surdacki, A. Golay, Differential associations of angiographic extent and severity of coronary artery disease with asymmetric dimethylarginine but not insulin resistance in non-diabetic men with stable angina: a crosssectional study, Cardiovasc. Diabetol. 12 (2013) 145. [17] Z. Wang, W.H. Tang, L. Cho, D.M. Brennan, S.L. Hazen, Targeted metabolomic evaluation of arginine methylation and cardiovascular risks: potential mechanisms beyond nitric oxide synthase inhibition, Arterioscler. Thromb. Vasc. Biol. 29 (2009) 1383–1391. [18] H. Borgeraas, E. Strand, E. Ringdal Pedersen, et al., Omega-3 status and the relationship between plasma asymmetric dimethylarginine and risk of myocardial infarction in patients with suspected coronary artery disease, Cardiol. Res. Pract. 2012 (2012) 201742. [19] F. Mangiacapra, E. Barbato, From SYNTAX to FAME, a paradigm shift in revascularization strategies: the key role of fractional flow reserve in guiding myocardial revascularization, J Cardiovasc Med (Hagerstown) 12 (2011) 538–542. [20] S. Tu, E. Barbato, Z. Köszegi, et al., Fractional flow reserve calculation from 3dimensional quantitative coronary angiography and TIMI frame count: a fast computer model to quantify the functional significance of moderately obstructed coronary arteries, JACC Cardiovasc. Interv. 7 (2014) 768–777. [21] N.P. Johnson, G.G. Toth, D. Lai, et al., Prognostic value of fractional flow reserve: linking physiologic severity to clinical outcomes, J. Am. Coll. Cardiol. 64 (2014) 1641–1654. [22] P.A. Tonino, B. De Bruyne, N.H. Pijls, et al., Fractional flow reserve versus angiography for guiding percutaneous coronary intervention, N. Engl. J. Med. 360 (2009) 213–224. [23] O. Muller, F. Mangiacapra, A. Ntalianis, et al., Long-term follow-up after fractional flow reserve-guided treatment strategy in patients with an isolated proximal left anterior descending coronary artery stenosis, JACC Cardiovasc. Interv. 4 (2011) 1175–1182. [24] E. Puymirat, A. Peace, F. Mangiacapra, et al., Long-term clinical outcome after fractional flow reserve-guided percutaneous coronary revascularization in patients with small-vessel disease, Circ Cardiovasc. Interv. 5 (2012) 62–68. [25] B. De Bruyne, W.F. Fearon, N.H. Pijls, et al., Fractional flow reserve-guided PCI for stable coronary artery disease, N. Engl. J. Med. (2014).
F. Mangiacapra et al. / International Journal of Cardiology 220 (2016) 629–633 [26] O. Muller, A. Ntalianis, W. Wijns, et al., Association of biomarkers of lipid modification with functional and morphological indices of coronary stenosis severity in stable coronary artery disease, J. Cardiovasc. Transl. Res. 6 (2013) 536–544. [27] J.W. Sels, E.H. Elsenberg, I.E. Hoefer, et al., Fractional flow reserve is not associated with inflammatory markers in patients with stable coronary artery disease, PLoS One 7 (2012), e46356. [28] P. Bogaty, S.J. Brecker, S.E. White, et al., Comparison of coronary angiographic findings in acute and chronic first presentation of ischemic heart disease, Circulation 87 (1993) 1938–1946. [29] G. Toth, M. Hamilos, S. Pyxaras, et al., Evolving concepts of angiogram: fractional flow reserve discordances in 4000 coronary stenoses, Eur. Heart J. 35 (2014) 2831–2838. [30] F. Schulze, R. Wesemann, E. Schwedhelm, et al., Determination of asymmetric dimethylarginine (ADMA) using a novel ELISA assay, Clin. Chem. Lab. Med. 42 (2004) 1377–1383. [31] R.M. Califf, P.W. Armstrong, J.R. Carver, R.B. D'Agostino, W.E. Strauss, 27th Bethesda conference: matching the intensity of risk factor management with the hazard for coronary disease events. Task Force 5. Stratification of patients into high, medium and low risk subgroups for purposes of risk factor management, J. Am. Coll. Cardiol. 27 (1996) 1007–1019.
633
[32] R. Hachamovitch, S.W. Hayes, J.D. Friedman, I. Cohen, D.S. Berman, Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography, Circulation 107 (2003) 2900–2907. [33] L.J. Shaw, D.S. Berman, D.J. Maron, et al., Optimal medical therapy with or without percutaneous coronary intervention to reduce ischemic burden: results from the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial nuclear substudy, Circulation 117 (2008) 1283–1291. [34] Z. Ajtay, F. Scalera, A. Cziraki, et al., Stent placement in patients with coronary heart disease decreases plasma levels of the endogenous nitric oxide synthase inhibitor ADMA, Int. J. Mol. Med. 23 (2009) 651–657. [35] Z. Ajtay, A. Nemeth, E. Sulyok, et al., Effects of stent implementation on plasma levels of asymmetric dimethylarginine in patients with or without ST-segment elevation acute myocardial infarction, Int. J. Mol. Med. 25 (2010) 617–624. [36] G. Lembo, C. Morisco, F. Lanni, et al., Systemic hypertension and coronary artery disease: the link, Am. J. Cardiol. 82 (1998) 2H–7H.
Contents lists available at ScienceDirect
International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard
Relationship of asymmetric dimethylarginine (ADMA) with extent and functional severity of coronary atherosclerosis Fabio Mangiacapra a,b, Micaela Conte a, Chiara Demartini b, Olivier Muller a, Leen Delrue a, Karen Dierickx a, Germano Di Sciascio b, Bruno Trimarco c, Bernard De Bruyne a, William Wijns a, Jozef Bartunek a, Emanuele Barbato a,c,⁎ a b c
Cardiovascular Center Aalst, OLV Clinic, Aalst, Belgium Department of Cardiovascular Sciences, Campus Bio-Medico University, Rome, Italy Division of Cardiology, Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy
a r t i c l e
i n f o
Article history: Received 21 March 2016 Received in revised form 16 June 2016 Accepted 27 June 2016 Available online 28 June 2016 Keywords: Asymmetric dimethylarginine Coronary atherosclerosis Fractional flow reserve
a b s t r a c t Background: Elevated serum levels of asymmetric dimethylarginine (ADMA) are associated with endothelial dysfunction and atherogenesis. In patients with suspected coronary artery disease (CAD), we assessed the correlation of serum ADMA levels with extent and functional significance of coronary atherosclerosis. Methods: We enrolled 281 patients with suspected CAD undergoing coronary angiogram. Angiographic CAD severity was evaluated by Bogaty score. In patients with angiographic evidence of at least one intermediate coronary stenosis (≥50% diameter stenosis), functional significance was assessed by fractional flow reserve (FFR). Blood samples were collected in all patients prior to coronary angiography for measurement of serum ADMA levels. Results: We observed across tertiles of ADMA levels increasingly higher values of both Stenosis Score (2.25 ± 1.70 vs. 2.89 ± 1.99 vs. 2.95 ± 1.82, p = 0.016) and Extent Index (0.52 ± 0.32 vs. 0.61 ± 0.39 vs. 0.72 ± 0.47, p = 0.003). The association between ADMA levels and Extent Index remained significant after multivariate adjustment (p = 0.005). Patients with FFR ≤0.80 in at least one vessel (n = 113) had significantly higher ADMA levels compared with patients without functionally significant CAD (0.51 [0.43–0.64] vs. 0.46 [0.39–0.58] μmol/L, p = 0.005). Serum ADMA levels were independent predictors of abnormal FFR after adjustment for extent score (odds ratio 7.35, 95% confidence interval 1.05–56.76, p = 0.046). Conclusions: Serum ADMA levels are independent predictors of coronary atherosclerosis extent and functional significance of CAD. © 2016 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide synthase (NOS), and increased ADMA levels have been linked to endothelial dysfunction [1–3]. ADMA levels have been correlated with the presence of peripheral atherosclerosis [1,4,5], and the occurrence of adverse cardiovascular events in different clinical settings [2, 6–11], including in patients with coronary artery disease (CAD) [12]. However, inconsistent results regarding the association between ADMA levels and the extent and severity of CAD have been reported. On one side, ADMA levels have been associated with increased coronary atherosclerosis and independently predicted CAD [11,13–16]. In other studies this finding was either not confirmed after multivariate adjustment [8, 17], or not found at all [18]. These discrepancies might be the consequence of several definitions of CAD and different methods used to ⁎ Corresponding author at: Cardiovascular Center Aalst, OLV Clinic, Moorselbaan 164, B9300 Aalst, Belgium. E-mail address: [email protected] (E. Barbato).
http://dx.doi.org/10.1016/j.ijcard.2016.06.254 0167-5273/© 2016 Elsevier Ireland Ltd. All rights reserved.
evaluate its extent and severity. Invasive functional assessment of coronary atherosclerosis severity by fractional flow reserve (FFR) is being increasingly used to target patients requiring coronary revascularization [19,20]. In fact, functional significance of CAD is a strong determinant of poor prognosis [21], and coronary revascularization when guided by FFR is associated with improved clinical outcomes [22–25]. Functional coronary stenosis severity assessed by FFR correlates with biomarkers of lipid modification [26] and inflammation [27]. In the present study we assessed the correlation of serum ADMA levels with the presence, extent and functional severity of coronary atherosclerosis as assessed by FFR in patients referred to coronary angiography. 2. Methods 2.1. Study population Consecutive patients older than 18 years with suspected stable CAD undergoing elective coronary angiography at Cardiovascular Center Aalst from March 2010 to February 2011 were considered for recruitment in the present study. Patients were excluded in case of: unstable angina, previous acute coronary syndrome, previous myocardial
630
F. Mangiacapra et al. / International Journal of Cardiology 220 (2016) 629–633
Table 1 Demographic and clinical characteristics. Total population
Male, n (%) Age, years BMI, kg/m2 Hypertension, n (%) Dyslipidemia, n (%) Diabetes mellitus, n (%) Smoking, n (%) Family history, n (%) eGFR (ml/min/1.73 m2) eGFR b 60 ml/min/1.73 m2, n (%) C reactive protein, mg/l LV ejection fraction, % LV end-diastolic pressure, mmHg LV end-diastolic volume, ml LV end-systolic volume, ml Medical therapy, n (%) Aspirin ACE inhibitors Angiotensin receptor blockers Beta blockers Calcium channel blockers Nitrates Statins
ADMA Tertiles
p value
Low
Medium
High
184 66 ± 12 27 ± 4 160 188 73 31 73 75 ± 20 58 (21) 1.58 [0.72–4.22] 69 ± 14 17 ± 7 148 ± 50 48 ± 34
62 (66) 65 ± 11 27 ± 5 49 (52) 60 (64) 21 (22) 15 (15) 25 (27) 78 ± 18 14 (15) 1.22 [0.71–2.99] 74 ± 12 15 ± 7 152 ± 56 42 ± 35
62 (66) 68 ± 12 27 ± 4 58 (62) 66 (70) 24 (26) 7 (7) 19 (20) 74 ± 21 20 (21) 1.90 [0.96–4.98] 68 ± 13 16 ± 7 148 ± 50 45 ± 26
60 (65) 66 ± 12 27 ± 5 53 (57) 62 (67) 28 (30) 9 (10) 29 (31) 72 ± 21 24 (26) 1.60 [0.74–4.02] 65 ± 15 19 ± 7 143 ± 42 57 ± 38
221 (79) 101 (36) 22 (8) 161 (57) 48 (17) 62 (22) 179 (64)
76 (81) 27 (29) 10 (11) 48 (51) 14 (15) 18 (19) 55 (59)
69 (73) 40 (43) 6 (6) 54 (57) 14 (15) 19 (20) 63 (67)
76 (82) 34 (37) 6 (6) 59 (63) 20 (22) 25 (27) 61 (66)
p value Low vs. High
0.972 0.112 0.465 0.415 0.868 0.477 0.155 0.228 0.078 0.180 0.219 b0.001 0.003 0.467 0.014
0.836 0.600 0.670 0.446 0.684 0.227 0.199 0.489 0.026 0.064 0.224 0.002 0.001 0.217 0.010
0.311 0.140 0.462 0.231 0.383 0.385 0.430
0.879 0.253 0.306 0.087 0.241 0.209 0.318
eGFR = estimated glomerular filtration rate; LV = left ventricle; ACE = angiotensin converting enzyme. revascularization, left ventricle ejection fraction b30%, severe valvular heart disease, endstage renal disease (estimated glomerular filtration rate b 15 ml/min/1.73 m2). In all patients traditional cardiovascular risk factors and medications taken on admission were recorded. The local Ethics Committee approved the study and all patients gave informed consent.
2.2. Coronary angiography and functional evaluation of CAD Coronary angiography was performed according to standard practice. Coronary stenosis was defined as a ≥50% by visual estimation in at least one major vessel. Angiographic analyses included the evaluation of angiographic CAD severity and extent by the Bogaty score [28]. Angiographic severity of disease (Stenosis Score) refers to the total number of ≥50% narrowings in all vessels of the angiogram. A maximum of three stenoses were permitted per coronary arterial segment. Extent of coronary disease (Extent Index) was obtained by dividing the extent score of the entire coronary arterial tree by the number of analyzed segments. A segment was scored 0 if it was angiographically normal, 1 if ≤10% of its length appeared abnormal, 2 if N10% up to 50% of its length was abnormal, and 3 if N50% of its length was abnormal. A total of 15 segments were considered, and therefore the Extent Index could range from 0 to 3. All angiographic analyses were performed by two independent operators (FM and MC), and discordances were resolved by consensus. In the presence of at least one coronary stenosis ≥50%, functional severity of CAD was assessed by measuring FFR [29]. A 6 French guide catheter was used to intubate coronary ostia and an intracoronary pressure/temperature sensor-tipped guidewire (PressureWire Certus, RADI, St Jude Medical, Uppsala, Sweden) was used to measure distal coronary pressure. FFR was calculated from the ratio of distal coronary pressure (Pd) to proximal coronary pressure (Pa) at maximal hyperemia. An FFR ≤0.80 was considered abnormal, identifying functionally significant coronary stenosis.
2.3. ADMA assessment A blood sample was obtained in all patients immediately before coronary angiography for determination of serum ADMA levels. ADMA levels were measured according to the manufacturer's instructions by a commercially available enzyme-linked immunosorbent assay (DLD Diagnostika GmbH., Hamburg, Germany), previously validated against highperformance liquid chromatography coupled to mass spectrometry, the golden standard for ADMA determinations [30]. Briefly, aliquots (50 μl) of pretreated standards, controls and samples were pipetted into the wells of the coated microtiter plate and 50 μl antiserum solution was added into all wells. The plate was incubated overnight at 2–8 °C and washed four times with wash buffer. Subsequently, 100 μl enzyme conjugate was added to each well and the microtiter plate was incubated for 1 h at room temperature. The wells were again washed four times. Substrate solution (100 μl) was added to the wells and the plate was incubated for 20 to 30 min at room temperature. Finally, the reaction was stopped with stop solution and optical density was read at 450 nm using a microplate photometer. Samples were measured in duplicate and the mean absorbance value was used to determine the ADMA concentration based on the standard curve. Data was presented as μmol/L. 2.4. Statistics Continuous variables are expressed as mean ± SD, or median [interquartile range]. Categorical variables are reported as frequencies and percentages. Normality of continuous variable distribution was tested with the Shapiro–Wilk test. One-way analysis of variance or Kruskall-Wallis test was used to compare continuous variables between tertiles of ACEF score. Comparisons between categorical variables were evaluated using Pearson χ2 test. Adjustments for repeated measures were performed when appropriate. Linear regression analysis was used to assess predictors of CAD extent (Extent Index). All variables with a significant (b0.05) univariate association with the outcome measure were included in the final multivariate model. The ability of ADMA levels to discriminate between patients with and without myocardial ischemia was assessed by receiver operating characteristic curves and associated area under the curve (AUC). The optimal cutoff point of ADMA score to discriminate between patients with and without myocardial ischemia was calculated by determining the value that provided the greatest sum of sensitivity and specificity. All statistical analyses were performed using STATA/IC 12 (STATA Corp., College Station, Texas) and a p value b0.05 was considered statistically significant.
3. Results
Fig. 1. Asymmetric dimethylarginine (ADMA) levels and the presence of coronary artery disease. Distribution of patients according to the number of vessels with at least one ≥50% stenosis in ADMA tertiles.
A total of 281 patients were enrolled. Median levels of ADMA were 0.483 μmol/L, ranging from 0.207 to 1.122 μmol/L. Clinical characteristics in the overall population and according to ADMA tertiles are reported in Table 1. Risk factors for CAD and medical therapy were not significantly different across ADMA tertiles, whereas renal function and left ventricular indices were significantly worse in patients with higher ADMA levels.
F. Mangiacapra et al. / International Journal of Cardiology 220 (2016) 629–633
631
Fig. 2. Asymmetric dimethylarginine (ADMA) levels and the extent of coronary artery disease. Stenosis Score (Panel A) and Extent Index (Panel B) values in ADMA tertiles.
At coronary angiography, 45 (16%) patients presented normal coronary arteries. At least one coronary stenosis (≥50%) was found in 1 vessel in 125 (44%) patients, in 2 vessels in 69 patients (25%), and in 3 vessels in 42 (15%) patients. The number of diseased vessels progressively increased across ADMA tertiles (p for trend 0.015; Fig. 1), with patients in the higher ADMA tertile presenting the highest prevalence of multivessel disease (52% vs. 27% in the lowest tertile; p b 0.001). We observed increasing values of both Stenosis Score (2.25 ± 1.70 vs. 2.89 ± 1.99 vs. 2.95 ± 1.82, p = 0.016; Fig. 2, Panel A) and Extent Index (0.52 ± 0.32 vs. 0.61 ± 0.39 vs. 0.72 ± 0.47, p = 0.003; Fig. 2, Panel B) across tertiles of ADMA levels. The association between ADMA levels and Extent Index remained significant after multivariate adjustment (p = 0.005; Table 2). Patients with abnormal FFR (e.g. ≤0.80) in at least one vessel (n = 113) had significantly higher ADMA levels as compared with patients with FFR N 0.80 for all measured lesions (0.51 [0.43–0.64] vs. 0.46 [0.39–0.58] μmol/L, p = 0.005; Fig. 3). ADMA levels were independent predictors of abnormal FFR after adjustment for extent score (odds ratio 7.35, 95% confidence interval 1.05–56.76, p = 0.046). At ROC curve analysis, ADMA levels could significantly discriminate between patients with and without abnormal FFR, with an AUC of 0.607 (95% CI 0.535–0.679, p = 0.005). The optimal cutoff to predict the presence of abnormal FFR was an ADMA level N 0.414 μmol/L, with a sensitivity of 82% and a specificity of 36%. When the entire population was divided in four groups based on FFR values (≤0.80 or N0.80) and Extent Index (below or above the median, 0.53), we observed that those patients with FFR N 0.80 and low Extent Index presented the lowest ADMA levels (0.46 [0.40–0.55]), whereas those with abnormal FFR and high Extent Index presented the highest ADMA levels (0.52 [0.45–0.65], p = 0.015; Fig. 4).
Table 2 Univariate and multivariate predictors of coronary artery disease extent (Extent Index). Univariate model
Age Male Hypertension Diabetes mellitus Dyslipidemia Smoking Family History ACE-inhibitors Statins eGFR b 60 ml/min/1.73 m2 C Reactive Protein ADMA levels
4. Discussion Main findings of the present study are: (1) serum ADMA levels significantly correlated with the presence and extent of coronary atherosclerosis in patients undergoing elective coronary angiogram; (2) those patients with functionally significant CAD (e.g. abnormal FFR) have significantly higher ADMA levels; (3) patients with the largest atherosclerotic burden (e.g. high Extent Index) and abnormal FFR have the highest levels of serum ADMA. Several studies have demonstrated that increasing levels of ADMA are associated with higher risk of adverse cardiovascular events in different clinical settings [2,6–12]. ADMA is a well-known marker of endothelial dysfunction [1–3], and it is likely that it could contribute to an increased atherosclerotic burden. However, previous investigations exploring the association between ADMA levels and coronary atherosclerosis have reported discordant results. In patients with stable CAD, ADMA levels were higher in patients with angiographically significant stenosis (≥50% in one major coronary artery) [13], and a significant positive correlation between ADMA levels and atherosclerotic burden and extent (number of vessels with ≥50% stenosis) was observed [14,15]. In a recent study [16], higher ADMA levels correlated significantly, even after multivariate adjustment, with CAD extent evaluated with the Sullivan score, but not with the Gensini score. In subsequent studies, these observations were partly confirmed, if at all. Discrepancies have possibly derived by the adoption of different threshold values to define angiographic coronary stenosis severity (e.g. ≥20%), different score indexes (e.g. Friesinger score) [8] or by including patients with acute coronary syndromes [18]. In fact, it has been shown that patients with acute myocardial infarction have higher serum ADMA levels [9], and therefore conflicting results may be yielded when including patients with acute coronary syndromes in study assessing the relation between ADMA levels and atherosclerosis extent. Our study confirms and further extends these previous evidences. We confirmed ADMA as an independent predictor of angiographic coronary atherosclerosis extent, as assessed with the well validated Bogaty score [28]. For the first time,
Multivariate model
Standardized B
p value
Standardized B
p value
0.175 0.215 0.100 0.137 0.133 0.207 0.157 0.182 0.002 0.140 0.028 0.217
0.004 b0.001 0.102 0.025 0.030 0.001 0.010 0.425 0.922 0.026 0.665 b0.001
0.180 0.224 – 0.101 0.126 0.177 0.129 – – 0.126 – 0.164
0.004 b0.001 – 0.082 0.030 0.004 0.029 – – 0.041 – 0.005
eGFR = estimated glomerular filtration rate; ACE = angiotensin converting enzyme; ADMA = asymmetric dimethylarginine.
Fig. 3. Asymmetric dimethylarginine (ADMA) levels and abnormal FFR.
632
F. Mangiacapra et al. / International Journal of Cardiology 220 (2016) 629–633
Conflict of interest No conflicts of interest to disclose.
References
Fig. 4. Association of asymmetric dimethylarginine (ADMA) levels with abnormal FFR and coronary atherosclerosis extent. EI = Extent Index; FFR = fractional flow reserve.
we demonstrated that ADMA is higher in patients with functionally significant coronary stenosis (e.g. abnormal FFR) irrespective of the angiographic stenosis severity. ADMA levels were able to discriminate between patients with and without coronary stenoses and abnormal FFR. Though, the highest ADMA levels were observed in those patients with abnormal FFR and large atherosclerotic burden (e.g. high Extent Index). Functionally significant CAD has been demonstrated to be a strong determinant of adverse events, including mortality [31–33], and recent trials have demonstrated that functionally guided revascularization strategies (i.e. FFR guided) are able to improve clinical outcomes [22–25]. In this context, our study may provide a mechanistic explanation for the predictive clinical value of ADMA. The highest values of ADMA were in fact observed in patients with combined extensive atherosclerotic burden and functionally significant stenoses, which are at higher risk of large ischemic myocardial areas. Furthermore, the evidence of a rapid and sustained decrease in ADMA levels after percutaneous coronary revascularization [34,35] confirms the link between ADMA and underlying ischemic substrate.
4.1. Limitations This study presents several limitations. First, the sample size is relatively small. Second, coronary atherosclerosis burden was only evaluated based on angiographic parameters. Intravascular techniques (e.g. optical coherence tomography, intravascular ultrasound) could have provided more detailed information on plaque composition and distribution. Third, no serial measurements of ADMA levels were performed, and therefore we were not able to detect potential changes in ADMA concentrations in patients receiving myocardial revascularization. Fourth, we cannot provide any mechanistic explanation for the association between myocardial ischemia and elevated ADMA levels. Fifth, no data on the duration of drug therapy is available for our patients, and we cannot exclude that cardiovascular drugs may exert a timedependent effect on ADMA levels [36]. Finally, no prospective followup data on cardiovascular events are available.
5. Conclusions The results of the present study confirm the association of ADMA with the presence and extent of coronary atherosclerosis, and indicate for the first time an increase of ADMA levels in the presence of functionally significant stenoses as documented with FFR. The identification of those patients with extensive and functionally significant atherosclerotic burden might explain the increased cardiovascular risk associated with high ADMA levels.
[1] H. Miyazaki, H. Matsuoka, J.P. Cooke, et al., Endogenous nitric oxide synthase inhibitor: a novel marker of atherosclerosis, Circulation 99 (1999) 1141–1146. [2] C. Zoccali, S. Bode-Boger, F. Mallamaci, et al., Plasma concentration of asymmetrical dimethylarginine and mortality in patients with end-stage renal disease: a prospective study, Lancet 358 (2001) 2113–2117. [3] J.P. Cooke, Asymmetrical dimethylarginine: the Uber marker? Circulation 109 (2004) 1813–1818. [4] K. Furuki, H. Adachi, H. Matsuoka, et al., Plasma levels of asymmetric dimethylarginine (ADMA) are related to intima-media thickness of the carotid artery: an epidemiological study, Atherosclerosis 191 (2007) 206–210. [5] R. Maas, V. Xanthakis, J.F. Polak, et al., Association of the endogenous nitric oxide synthase inhibitor ADMA with carotid artery intimal media thickness in the Framingham Heart Study offspring cohort, Stroke 40 (2009) 2715–2719. [6] V.P. Valkonen, H. Paiva, J.T. Salonen, et al., Risk of acute coronary events and serum concentration of asymmetrical dimethylarginine, Lancet 358 (2001) 2127–2128. [7] R. Schnabel, S. Blankenberg, E. Lubos, 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. 97 (2005) e53–e59. [8] A. Meinitzer, U. Seelhorst, B. Wellnitz, et al., Asymmetrical dimethylarginine independently predicts total and cardiovascular mortality in individuals with angiographic coronary artery disease (the Ludwigshafen Risk and Cardiovascular Health study), Clin. Chem. 53 (2007) 273–283. [9] R.H. Boger, R. Maas, F. Schulze, E. Schwedhelm, Asymmetric dimethylarginine (ADMA) as a prospective marker of cardiovascular disease and mortality—an update on patient populations with a wide range of cardiovascular risk, Pharmacol. Res. 60 (2009) 481–487. [10] R.H. Boger, L.M. Sullivan, E. Schwedhelm, et al., Plasma asymmetric dimethylarginine and incidence of cardiovascular disease and death in the community, Circulation 119 (2009) 1592–1600. [11] T.M. Lu, M.Y. Chung, M.W. Lin, C.P. Hsu, S.J. Lin, Plasma asymmetric dimethylarginine predicts death and major adverse cardiovascular events in individuals referred for coronary angiography, Int. J. Cardiol. 153 (2011) 135–140. [12] T.M. Lu, Y.A. Ding, S.J. Lin, W.S. Lee, H.C. Tai, Plasma levels of asymmetrical dimethylarginine and adverse cardiovascular events after percutaneous coronary intervention, Eur. Heart J. 24 (2003) 1912–1919. [13] T.M. Lu, Y.A. Ding, M.J. Charng, S.J. Lin, Asymmetrical dimethylarginine: a novel risk factor for coronary artery disease, Clin. Cardiol. 26 (2003) 458–464. [14] T. Thum, D. Tsikas, S. Stein, et al., Suppression of endothelial progenitor cells in human coronary artery disease by the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine, J. Am. Coll. Cardiol. 46 (2005) 1693–1701. [15] F. Schulze, H. Lenzen, C. Hanefeld, et al., Asymmetric dimethylarginine is an independent risk factor for coronary heart disease: results from the multicenter Coronary Artery Risk Determination investigating the Influence of ADMA Concentration (CARDIAC) study, Am. Heart J. 152 (2006) 493, e1–493.e8. [16] O. Kruszelnicka, A. Surdacki, A. Golay, Differential associations of angiographic extent and severity of coronary artery disease with asymmetric dimethylarginine but not insulin resistance in non-diabetic men with stable angina: a crosssectional study, Cardiovasc. Diabetol. 12 (2013) 145. [17] Z. Wang, W.H. Tang, L. Cho, D.M. Brennan, S.L. Hazen, Targeted metabolomic evaluation of arginine methylation and cardiovascular risks: potential mechanisms beyond nitric oxide synthase inhibition, Arterioscler. Thromb. Vasc. Biol. 29 (2009) 1383–1391. [18] H. Borgeraas, E. Strand, E. Ringdal Pedersen, et al., Omega-3 status and the relationship between plasma asymmetric dimethylarginine and risk of myocardial infarction in patients with suspected coronary artery disease, Cardiol. Res. Pract. 2012 (2012) 201742. [19] F. Mangiacapra, E. Barbato, From SYNTAX to FAME, a paradigm shift in revascularization strategies: the key role of fractional flow reserve in guiding myocardial revascularization, J Cardiovasc Med (Hagerstown) 12 (2011) 538–542. [20] S. Tu, E. Barbato, Z. Köszegi, et al., Fractional flow reserve calculation from 3dimensional quantitative coronary angiography and TIMI frame count: a fast computer model to quantify the functional significance of moderately obstructed coronary arteries, JACC Cardiovasc. Interv. 7 (2014) 768–777. [21] N.P. Johnson, G.G. Toth, D. Lai, et al., Prognostic value of fractional flow reserve: linking physiologic severity to clinical outcomes, J. Am. Coll. Cardiol. 64 (2014) 1641–1654. [22] P.A. Tonino, B. De Bruyne, N.H. Pijls, et al., Fractional flow reserve versus angiography for guiding percutaneous coronary intervention, N. Engl. J. Med. 360 (2009) 213–224. [23] O. Muller, F. Mangiacapra, A. Ntalianis, et al., Long-term follow-up after fractional flow reserve-guided treatment strategy in patients with an isolated proximal left anterior descending coronary artery stenosis, JACC Cardiovasc. Interv. 4 (2011) 1175–1182. [24] E. Puymirat, A. Peace, F. Mangiacapra, et al., Long-term clinical outcome after fractional flow reserve-guided percutaneous coronary revascularization in patients with small-vessel disease, Circ Cardiovasc. Interv. 5 (2012) 62–68. [25] B. De Bruyne, W.F. Fearon, N.H. Pijls, et al., Fractional flow reserve-guided PCI for stable coronary artery disease, N. Engl. J. Med. (2014).
F. Mangiacapra et al. / International Journal of Cardiology 220 (2016) 629–633 [26] O. Muller, A. Ntalianis, W. Wijns, et al., Association of biomarkers of lipid modification with functional and morphological indices of coronary stenosis severity in stable coronary artery disease, J. Cardiovasc. Transl. Res. 6 (2013) 536–544. [27] J.W. Sels, E.H. Elsenberg, I.E. Hoefer, et al., Fractional flow reserve is not associated with inflammatory markers in patients with stable coronary artery disease, PLoS One 7 (2012), e46356. [28] P. Bogaty, S.J. Brecker, S.E. White, et al., Comparison of coronary angiographic findings in acute and chronic first presentation of ischemic heart disease, Circulation 87 (1993) 1938–1946. [29] G. Toth, M. Hamilos, S. Pyxaras, et al., Evolving concepts of angiogram: fractional flow reserve discordances in 4000 coronary stenoses, Eur. Heart J. 35 (2014) 2831–2838. [30] F. Schulze, R. Wesemann, E. Schwedhelm, et al., Determination of asymmetric dimethylarginine (ADMA) using a novel ELISA assay, Clin. Chem. Lab. Med. 42 (2004) 1377–1383. [31] R.M. Califf, P.W. Armstrong, J.R. Carver, R.B. D'Agostino, W.E. Strauss, 27th Bethesda conference: matching the intensity of risk factor management with the hazard for coronary disease events. Task Force 5. Stratification of patients into high, medium and low risk subgroups for purposes of risk factor management, J. Am. Coll. Cardiol. 27 (1996) 1007–1019.
633
[32] R. Hachamovitch, S.W. Hayes, J.D. Friedman, I. Cohen, D.S. Berman, Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography, Circulation 107 (2003) 2900–2907. [33] L.J. Shaw, D.S. Berman, D.J. Maron, et al., Optimal medical therapy with or without percutaneous coronary intervention to reduce ischemic burden: results from the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial nuclear substudy, Circulation 117 (2008) 1283–1291. [34] Z. Ajtay, F. Scalera, A. Cziraki, et al., Stent placement in patients with coronary heart disease decreases plasma levels of the endogenous nitric oxide synthase inhibitor ADMA, Int. J. Mol. Med. 23 (2009) 651–657. [35] Z. Ajtay, A. Nemeth, E. Sulyok, et al., Effects of stent implementation on plasma levels of asymmetric dimethylarginine in patients with or without ST-segment elevation acute myocardial infarction, Int. J. Mol. Med. 25 (2010) 617–624. [36] G. Lembo, C. Morisco, F. Lanni, et al., Systemic hypertension and coronary artery disease: the link, Am. J. Cardiol. 82 (1998) 2H–7H.