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Coronary collaterals: The role of MCP-1 during the early phase of acute myocardial infarction
International Journal of Cardiology 130 (2008) 409 – 413 www.elsevier.com/locate/ijcard
Coronary collaterals: The role of MCP-1 during the early phase of acute myocardial infarction Hun-Jun Park a,b , Kiyuk Chang a,b,⁎, Chan Seok Park a , Sung Won Jang a , Sang-Hyun Ihm a , Pum Joon Kim a , Sang-Hong Baek a , Ki-Bae Seung a , Kyu-Bo Choi a a b
Division of Cardiology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea Division of Cardiology, Department of Medicine, Uijungbu St. Mary’s Hospital, The Catholic University of Korea, Seoul, Republic of Korea Received 15 February 2007; received in revised form 13 August 2007; accepted 18 August 2007 Available online 26 December 2007
Abstract Background: The collateral growth (arteriogenesis) of an individual may vary from complete to absent during the early phase of acute myocardial infarction (AMI). However, the mechanisms underlying the large differences in the extent and adequacy of collateralization remain unclear. We hypothesized that shear stress-induced activation of monocyte chemoattractant protein-1 could potently contribute to the development of coronary collaterals during the early phase of AMI. Methods: We enrolled forty patients with AMI who did not receive reperfusion therapy within 24 h after the onset of chest pain and who also underwent coronary angiography (CAG) from 1 to 7 days after admission (mean duration: 3.6 ± 2.2 days). The grades of the collateral development were angiographically defined and grouped according to the grade of collaterals as absent (score 0, n = 20) or well-developed (score 2, n = 20) collateral circulation. The plasma concentrations of vascular endothelial growth factor (VEGF), endostatin, monocyte chemoattractant protein-1 (MCP-1), and stromal cell-derived factor-1 (SDF-1) were assessed by enzyme-linked immunosorbent assay and then these values were compared between the two groups. Results: There were no differences in the demographic and angiographic characteristics except for the number of total occlusion in culprit lesion. The plasma MCP-1 levels were significantly higher in the group with well-developed collateral circulation compared to the group with absent collateral circulation (262 ± 216 vs. 151 ± 88 pg/ml, respectively, p = 0.043). However, the plasma levels of VEGF, endostatin and SDF-1 were not different on comparisons between the groups (VEGF; 369 ± 377 vs. 324 ± 363 pg/ml, endostatin; 1.74 ± 1.71 vs. 1.49 ± 1.15 ng/ml, SDF-1; 1806 ± 508 vs. 2091 ± 772 pg/ml, respectively). Conclusion: During the early phase of AMI, the plasma levels of MCP-1 were significantly increased in the patients with well-developed collateral circulation as compared to those patients with absent collateral circulation. These findings suggested that the shear stress-induced overexpression of MCP-1 contributes significantly to the development of coronary collaterals during the early phase of AMI. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Collateral circulation; Arteriogenesis; Myocardial infarction; Monocyte chemoattractant protein-1
1. Introduction The formation of coronary collaterals is an adaptive response of the coronary vascular system to arterial occlusion. ⁎ Correspondence author. Division of Cardiology, Department of Medicine, Uijungbu St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea. Tel.: +82 31 820 3000; fax : +82 31 847 0461. E-mail address: [email protected] (K. Chang). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.08.128
This process is involved in restoring coronary blood flow and salvaging the myocardium at ischemic regions. Previous studies have shown that the presence of collaterals may limit the size of an infarct, preserve the viability, and prevent ventricular aneurysm formation during an episode of acute coronary occlusion [1–4]. During the early phase of acute myocardial infarction (AMI), patients will show marked angiographic heterogeneity in collateral formation that is independent of the status of coronary artery occlusion [5]. However, the mechanism underlying these large differences
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between individual patients in the extent and adequacy of collateralization remains unclear despite of our increased understanding of the cellular and molecular processes involved in collateral development. The sudden occlusion of an epicardial coronary artery creates a pressure gradient between the arteries proximal to the occlusion and distal from the occlusion, and this increases the blood flow through the preexisting arterioles. This shear stress activates the endothelium of the preexisting arterioles and it stimulates the production of various growth factors and cytokines, including monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and etc [6–12]. This interplay of cells, growth factors and cytokines results in arteriogenesis, which is a process of opening and maturation of preexisting small arterioles; this is thought to play a major role in the formation of angiographically visible collaterals in patients with AMI and who do not undergo reperfusion therapy. Among the various growth factors and cytokines, we hypothesized that MCP-1 activation would more potently contribute to the development of angiographically visible coronary collaterals during the early phase of AMI than any other growth factors and cytokines. Thus, we compared the plasma levels of MCP-1, VEGF, endostatin and stromal cellderived factor-1 (SDF-1) between the patients with angiographically visible collaterals and those patients without collaterals. 2. Methods and materials 2.1. Patient selection Among the patients with AMI at Kangnam St. Mary's hospital who did not receive reperfusion therapy within 24 h after the onset of chest pain, 40 patients who underwent coronary angiography (CAG) from 1 to 7 days after admission (mean duration: 3.6 ± 2.2 days) were selected and they were then divided into 2 groups: group 1 had an angiographically demonstrated absence of collateral circulation (score 0, n = 20) and group 2 had well-developed (score 2, n = 20) collateral circulation. AMI was diagnosed based on chest pain that persisted for 30 min, elevation of the serum creatine kinase-MB fraction (CK-MB) to more than twice the upper limit of normal, and elevation of the serum troponin I level above the upper limit of normal according to the local quantitative or qualitative assays. ST elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI) were included as AMI. The criteria for exclusion from the study were the following: 1) patients with AMI who received thrombolysis or primary percutaneous coronary intervention within 24 h after the onset of chest pain; 2) patients who suffered with recent MI or old MI that happened more than 7 days after the onset of chest pain; 3) patients with collateral formation due to a non-culprit lesion, as seen on the CAG; 4) patients who previously underwent CABG.
2.2. Blood sampling and coronary angiography Immediately before coronary angiography, a blood sample was obtained from each patient through the introducer sheath that was placed in the femoral artery, and this sample was aliquoted in a 10 ml sterile tube (anticoagulant: EDTA) and then processed within 30 min. Standard angiography, with ≥ 4 views of the left coronary system and 2 views of the right coronary artery, was used for interpretation. The collateral scoring system we used was modified from the previously described Thrombolysis In Myocardial Infarction Scoring System [2]. The ranking from 0 to 2 was based on the presence of collateral vessels and opacification of the recipient vessel. A grade of 0 was given for no visible collaterals, a grade of 1 was given for visible collaterals, but there was no filling of the recipient epicardial vessels, and a grade of 2 was given for filling (partial or complete) of the recipient epicardial vessels by the collaterals. A separate angiographer, who was blinded to the initial reading, reviewed the angiograms. For the cases of disagreement, a third angiographer, who was blinded to the initial two readings, served as an arbitrator. 2.3. Measurement of growth factors The whole blood samples were centrifuged at 3000 rpm for 10 min at room temperature. The plasma supernatant was removed, frozen in liquid nitrogen and then stored at − 80 °C in aliquots that were used for the growth factor level assays. Standard enzyme-linked immunosorbent assay kits (R&D Systems, Inc., USA) were used to determine the plasma growth factor levels of VEGF, endostatin, MCP-1 and SDF-1. 2.4. Data collection and statistical analysis The clinical data was obtained from a comprehensive review of each patient's medical record and with using the established criteria for hypertension, diabetes mellitus, hyperlipidemia and myocardial infarction. Current smoking was defined as the active use of tobacco products at the time of enrollment into the study. Analysis between groups for statistically significant differences in the categorical data was performed using the chi-square test. The continuous variables are presented as mean ± standard deviation (SD), and they were compared by Student's T test. A p value below 0.05 was considered statistically significant. 3. Results 3.1. Baseline characteristics and the cardiac enzymes Table 1 summarizes the patient's profiles and the cardiac enzymes by the group. The mean age and the proportion of patients with angina or prior MI were higher in the group with well-developed collateral circulation, but the differences
H.-J. Park et al. / International Journal of Cardiology 130 (2008) 409–413 Table 1 Baseline characteristics and cardiac enzymes
Clinical variables Age, years Male, n (%) Hypertension, n (%) Diabetes, n (%) Smoking, n (%) Hyperlipidemia, n (%) Angina, n (%) Prior MI, n (%) Prior PCI, n (%) Duration from onset of chest pain, (days) Cardiac enzymes CK-MBinitial (ng/ml) CK-MBpeak (ng/ml) Troponin Iinitial (ng/ml) Troponin Ipeak (ng/ml)
Table 2 Angiographic characteristics
Collateral (−) (N = 20)
Collateral (+) (N = 20)
p
57 ± 12 14 (70) 12 (60) 8 (40) 10 (50) 9 (45) 5 (25) 0 (0) 1 (5) 3.5 ± 2.3
64 ± 13 12 (60) 15 (75) 8 (40) 12 (60) 9 (45) 6 (30) 1 (5) 1 (5) 3.8 ± 2.2
0.11 0.51 0.31 1.00 0.53 1.00 0.72 0.31 1.00 0.68
Collateral (−)
46.9 ± 55.1 85.9 ± 95.1 16.4 ± 18.5 29.7 ± 21.6
0.66 0.63 0.74 0.18
were not statistically meaningful. The mean duration from the onset of chest pain to CAG was not different between the two groups. Although the levels of cardiac enzymes such as CKMB and troponin I were lower in the group with welldeveloped collateral circulation than those levels in the other
Collateral (+)
p
Number of diseased vessels a 1, n (%) 9 (45) 2, n (%) 4 (20) 3, n (%) 7 (30)
5 (25) 7 (35) 8 (40)
0.36
Location of culprit lesions LAD, n (%) 8 (40) LCX, n (%) 5 (25) RCA, n (%) 7 (35)
11 (55) 0 (0) 9 (45)
0.06
Number of totally occluded culprit lesions, n (%) 6 (30) 17 (85) a
55.3 ± 64.0 99.3 ± 79.4 18.4 ± 18.9 38.4 ± 17.8
411
b0.001
Defined as N50% stenosis of the lesion according to the angiography.
group, there were no statistically significant differences between them. 3.2. Comparison between the group with the absent collateral circulation and the group with well-developed collateral circulation Fig. 1A shows the representative coronary angiography for a patient with markedly visible collaterals during the early phase of AMI. Although his left anterior descending
Fig. 1. The difference of collateral response between the individual patients. (A) shows a representative coronary angiography for a patient with marked visible collaterals during the early phase of AMI. Although his left anterior descending artery was totally occluded, it was well filled by collaterals that arose from the right coronary artery. On the other hand, (B) shows the coronary angiography for a patient without visible collaterals. Despite total occlusion of the left circumflex artery, there were no visible collaterals on the CAG.
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Fig. 2. Comparison of growth factors between the group without well-developed collateral circulation and the group with well-developed collateral circulation.
artery was totally occluded, it was well filled by collaterals that arose from the right coronary artery. On the other hand, Fig. 1B shows the coronary angiography for a patient without visible collaterals. Despite total occlusion of the left circumflex artery, there were no visible collaterals noted on the CAG. Table 2 shows the angiographic characteristics according to the group. The proportion of patients with more than two-vessel disease was higher in the group with a score of 2 compared to that of the group with a score of 0. However, the number of diseased vessels and the location of the culprit lesions were not statistically different on comparisons between the two groups. There was a significant difference in the number of totally occluded culprit lesions (score 0: n = 6, score 2: n = 17, p b 0.001). Fig. 2 shows the plasma levels of several growth factors according to the group. The plasma MCP-1 levels were significantly higher in the group with a score of 2 compared to those levels of the patients in the group with a score of 0 (262 ± 216 pg/ml vs. 151 ± 88, p = 0.043). However, the plasma levels of VEGF, endostatin and SDF-1 were not different on comparisons between the groups (VEGF; 369 ± 377 vs. 324 ± 363 pg/ml, endostatin; 1.74 ± 1.71 vs. 1.49 ± 1.15 ng/ml, SDF-1; 1806 ± 508 vs. 2091 ± 772 pg/ml, respectively). 4. Discussion The present study shows that plasma levels of MCP-1 were significantly increased in the patients with visible collaterals during the early phase of AMI, as compared with those patients without visible collaterals during the early phase of AMI. However, the plasma levels of VEGF, endostatin and SDF-1 were not different between the two groups. These findings suggest that MCP-1 may play an
important role in the development of collaterals during the early phase of AMI. 4.1. The collateral response during the early phase of AMI As observed in many cases, the collateral growth of an individual may vary from complete to absent during the early phase of AMI. The clinical or environmental factors that influence the development of coronary collaterals in patients with coronary artery disease are the severity of stenosis and the duration of the myocardial ischemic symptoms [13,14]. However, few studies have been conducted to investigate the association between collateral formation and cytokines during the early phase of AMI in human. There are different regulatory mechanisms and associated growth factors involved in the formation of coronary collaterals [6–12]. Immediately after occlusion of a coronary artery, the blood flow is redistributed through the preexisting arterioles that connect a high-pressure area to a low-pressure area. This results in an increased flow velocity and also shear stress in the preexisting arterioles, which activates the endothelium. The activated endothelium of the preexisting arterioles upregulates MCP-1 production and the expression of adhesion molecules. It has been observed that the targeted disruption of the MCP-1 receptor in mice prevents all collateral growth [15] but an infusion of MCP-1 into the proximal stump of the occluded femoral artery led to strong arteriogenesis [16]; this suggests that monocyte recruitment and activation, and the upregulation of MCP-1 seem to be very important for the promotion of arteriogenesis. VEGF has been reported to contribute to arteriogenesis, and VEGF affects monocyte chemotaxis via the VEGF receptor-1 [17,18] and it increases endothelial adhesion and transmi-
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gration of monocytes [19]. However, as was shown in our study on comparing the plasma levels of MCP-1 and VEGF according to the grade of collateral development during the early phase of AMI, VEGF did not significantly contribute to the development of visible collaterals, although MCP-1 enhanced arteriogenesis. Endostatin and SDF-1 are other potent factors affecting collateral formation, and these factors may influence arteriogenesis in AMI patients. Endostatin is an antiangiogenic factor and it has been reported to modulate coronary collateral formation in patients with ischemic heart disease [20]. It is interesting that endostatin is increased in patients with AMI before reperfusion therapy as compared with that of the control subjects and it is significantly decreased after reperfusion [21]. While SDF-1 is known to be the ligand for the G-protein coupled receptor CXCR4 and mediate its effect through recruitment of endothelial progenitor cells [22], some studies have reported that SDF1 is significantly upregulated in tissues that are derived from an area of collaterals after acute hindlimb ischemia in mice [23], and systemically administered SDF-1 could enhance arteriogenesis, at least in part, via its direct effects on the endothelium of preexisting arterioles in a rat model of vascular insufficiency [24]. However, we did not find any association between the plasma levels of endostatin and SDF-1 and the development of visible collaterals during the early phase of AMI. Further large scale studies will be required to elucidate the role of endostatin and SDF-1 in the formation of visible collaterals during the early phase of AMI. 4.2. Study limitations First, we did not examine the plasma levels of growth factors in the normal controls and we could not compare these between the patients with AMI and the controls. Second, several growth factors and cytokines are produced locally in ischemic cardiac tissue and they are lower in the systemic circulation because of dilution upon washout. In this study, we used the plasma of arterial samples to measure the concentration of growth factors, and this type of plasma is subject to the influence of washout and so it may not necessarily demonstrate a gradient. References [1] Ishihara M, Inoue I, Kawagoe T, et al. Comparison of the cardioprotective effect of prodromal angina pectoris and collateral circulation in patients with a first anterior wall acute myocardial infarction. Am J Cardiol 2005;95:622–5. [2] Habib GB, Heibig J, Forman SA, et al. Influence of coronary collateral vessels on myocardial infarct size in human. Results of phase I Thrombolysis In Myocardial Infarction (TIMI) trial. The TIMI Investigators. Circulation 1991;83:739–46. [3] Sabia PJ, Powers ER, Ragosta M, Sarembock IJ, Burwell LR, Kaul S. An association between collateral blood flow and myocardial viability in patients with recent myocardial infarction. N Engl J Med 1992;327: 1825–31.
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[4] Hirai T, Fujita M, Nakajima H, et al. Importance of collateral circulation for prevention of left ventricular aneurysm formation in acute myocardial infarction. Circulation 1989;79:791–6. [5] Antoniucci D, Valenti R, Moschi G, et al. Relation between preintervention angiographic evidence of coronary collateral circulation and clinical and angiographic outcomes after primary angioplasty or stenting for acute myocardial infarction. Am J Cardiol 2002; 89:121–5. [6] Schaper W, Ito W. Molecular mechanisms of coronary collateral vessel growth. Circ Res 1996;79:911–9. [7] Carmeliet P. Mechanisms of angiogenesis and arteriogenesis. Nat Med 2000;6:389–95. [8] Buschmann I, Schaper W. The pathophysiology of the collateral circulation (arteriogenesis). J Pathol 2000;190:338–42. [9] Scholz D, Cai WJ, Schaper W. Arteriogenesis, a new concept of vascular adaptation in occlusive disease. Angiogenesis 2001;4: 247–57. [10] Helisch A, Schaper W. Arteriogenesis: the development and growth of collateral arteries. Microcirculation 2003;10:83–97. [11] Schaper W, Scholz D. Factors regulating arteriogenesis. Arterioscler Thromb Vasc Biol 2003;23:1143–51. [12] Heil M, Schaper W. Influence of mechanical, cellular, and molecular factors on collateral artery growth (arteriogenesis). Circ Res 2004;95: 449–58. [13] Pohl T, Seiler C, Billinger M, et al. Frequency distribution of collateral flow and factors influencing collateral channel development. Functional collateral channel measurement in 450 patients with coronary artery disease. J Am Coll Cardiol 2001;38:1872–8. [14] Piek JJ, Koolen JJ, Hoedemaker G, David GK, Visser CA, Dunning AJ. Severity of single-vessel coronary arterial stenosis and duration of angina as determinants of recruitable collateral vessels during balloon occlusion. Am J Cardiol 1991;67:13–7. [15] Heil M, Ziegelhoeffer T, Wagner S, et al. Collateral artery growth (arteriogenesis) after experimental arterial occlusion is impaired in mice lacking CC-chemokine receptor-2. Circ Res 2004;94:671–7. [16] Ito WD, Arras M, Winkler B, Scholz D, Schaper J, Schaper W. Monocyte chemotactic protein-1 increases collateral and peripheral conductance after femoral artery occlusion. Circ Res 1997;80:829–37. [17] Clauss M, Weich H, Breier G, et al. The vascular endothelial growth factor receptor Flt-1 mediates biological activities: implications for a functional role of placenta growth factor in monocyte activation and chemotaxis. J Biol Chem 1996;271:17629–34. [18] Pipp F, Heil M, Issbrucker K, et al. VEGFR-1 selective VEGF homologue PIGF is arteriogenic: evidence for a monocyte-mediated mechanism. Circ Res 2003;92:378–85. [19] Heil M, Clauss M, Suzuki K, et al. Vascular endothelial growth factor (VEGF) stimulates monocyte migration through endothelial monolayers via increased integrin expression. Eur J Cell Biol 2000;79: 850–7. [20] Panchal VR, Rehman J, Nguyen AT, et al. Reduced pericardial levels of endostatin correlate with collateral development in patients with ischemic heart disease. J Am Coll Cardiol 2004;43:1383–7. [21] Seko Y, Fukuda S, Nagai R. Serum levels of endostatin, vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) in patients with acute myocardial infarction undergoing early reperfusion therapy. Clin Sci 2004;106:439–42. [22] Yamaguchi J, Kusano KF, Masuo O, et al. Stromal cell-derived factor-1 effects on ex vivo expanded endothelial progenitor cell recruitment for ischemic neovascularization. Circulation 2003;107:1322–8. [23] Lee CW, Stabile E, Kinnaird T, et al. Temporal patterns of gene expression after acute hindlimb ischemia in mice — insights into the genomic program for collateral vessel development. J Am Coll Cardiol 2004;43:474–82. [24] Carr AN, Howard BW, Yang HT, et al. Efficacy of systemic administration of SDF-1 in a model of vascular insufficiency: support for an endothelium-dependent mechanism. Cardiovasc Res 2006;69: 925–35.
Coronary collaterals: The role of MCP-1 during the early phase of acute myocardial infarction Hun-Jun Park a,b , Kiyuk Chang a,b,⁎, Chan Seok Park a , Sung Won Jang a , Sang-Hyun Ihm a , Pum Joon Kim a , Sang-Hong Baek a , Ki-Bae Seung a , Kyu-Bo Choi a a b
Division of Cardiology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea Division of Cardiology, Department of Medicine, Uijungbu St. Mary’s Hospital, The Catholic University of Korea, Seoul, Republic of Korea Received 15 February 2007; received in revised form 13 August 2007; accepted 18 August 2007 Available online 26 December 2007
Abstract Background: The collateral growth (arteriogenesis) of an individual may vary from complete to absent during the early phase of acute myocardial infarction (AMI). However, the mechanisms underlying the large differences in the extent and adequacy of collateralization remain unclear. We hypothesized that shear stress-induced activation of monocyte chemoattractant protein-1 could potently contribute to the development of coronary collaterals during the early phase of AMI. Methods: We enrolled forty patients with AMI who did not receive reperfusion therapy within 24 h after the onset of chest pain and who also underwent coronary angiography (CAG) from 1 to 7 days after admission (mean duration: 3.6 ± 2.2 days). The grades of the collateral development were angiographically defined and grouped according to the grade of collaterals as absent (score 0, n = 20) or well-developed (score 2, n = 20) collateral circulation. The plasma concentrations of vascular endothelial growth factor (VEGF), endostatin, monocyte chemoattractant protein-1 (MCP-1), and stromal cell-derived factor-1 (SDF-1) were assessed by enzyme-linked immunosorbent assay and then these values were compared between the two groups. Results: There were no differences in the demographic and angiographic characteristics except for the number of total occlusion in culprit lesion. The plasma MCP-1 levels were significantly higher in the group with well-developed collateral circulation compared to the group with absent collateral circulation (262 ± 216 vs. 151 ± 88 pg/ml, respectively, p = 0.043). However, the plasma levels of VEGF, endostatin and SDF-1 were not different on comparisons between the groups (VEGF; 369 ± 377 vs. 324 ± 363 pg/ml, endostatin; 1.74 ± 1.71 vs. 1.49 ± 1.15 ng/ml, SDF-1; 1806 ± 508 vs. 2091 ± 772 pg/ml, respectively). Conclusion: During the early phase of AMI, the plasma levels of MCP-1 were significantly increased in the patients with well-developed collateral circulation as compared to those patients with absent collateral circulation. These findings suggested that the shear stress-induced overexpression of MCP-1 contributes significantly to the development of coronary collaterals during the early phase of AMI. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Collateral circulation; Arteriogenesis; Myocardial infarction; Monocyte chemoattractant protein-1
1. Introduction The formation of coronary collaterals is an adaptive response of the coronary vascular system to arterial occlusion. ⁎ Correspondence author. Division of Cardiology, Department of Medicine, Uijungbu St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea. Tel.: +82 31 820 3000; fax : +82 31 847 0461. E-mail address: [email protected] (K. Chang). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.08.128
This process is involved in restoring coronary blood flow and salvaging the myocardium at ischemic regions. Previous studies have shown that the presence of collaterals may limit the size of an infarct, preserve the viability, and prevent ventricular aneurysm formation during an episode of acute coronary occlusion [1–4]. During the early phase of acute myocardial infarction (AMI), patients will show marked angiographic heterogeneity in collateral formation that is independent of the status of coronary artery occlusion [5]. However, the mechanism underlying these large differences
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between individual patients in the extent and adequacy of collateralization remains unclear despite of our increased understanding of the cellular and molecular processes involved in collateral development. The sudden occlusion of an epicardial coronary artery creates a pressure gradient between the arteries proximal to the occlusion and distal from the occlusion, and this increases the blood flow through the preexisting arterioles. This shear stress activates the endothelium of the preexisting arterioles and it stimulates the production of various growth factors and cytokines, including monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and etc [6–12]. This interplay of cells, growth factors and cytokines results in arteriogenesis, which is a process of opening and maturation of preexisting small arterioles; this is thought to play a major role in the formation of angiographically visible collaterals in patients with AMI and who do not undergo reperfusion therapy. Among the various growth factors and cytokines, we hypothesized that MCP-1 activation would more potently contribute to the development of angiographically visible coronary collaterals during the early phase of AMI than any other growth factors and cytokines. Thus, we compared the plasma levels of MCP-1, VEGF, endostatin and stromal cellderived factor-1 (SDF-1) between the patients with angiographically visible collaterals and those patients without collaterals. 2. Methods and materials 2.1. Patient selection Among the patients with AMI at Kangnam St. Mary's hospital who did not receive reperfusion therapy within 24 h after the onset of chest pain, 40 patients who underwent coronary angiography (CAG) from 1 to 7 days after admission (mean duration: 3.6 ± 2.2 days) were selected and they were then divided into 2 groups: group 1 had an angiographically demonstrated absence of collateral circulation (score 0, n = 20) and group 2 had well-developed (score 2, n = 20) collateral circulation. AMI was diagnosed based on chest pain that persisted for 30 min, elevation of the serum creatine kinase-MB fraction (CK-MB) to more than twice the upper limit of normal, and elevation of the serum troponin I level above the upper limit of normal according to the local quantitative or qualitative assays. ST elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI) were included as AMI. The criteria for exclusion from the study were the following: 1) patients with AMI who received thrombolysis or primary percutaneous coronary intervention within 24 h after the onset of chest pain; 2) patients who suffered with recent MI or old MI that happened more than 7 days after the onset of chest pain; 3) patients with collateral formation due to a non-culprit lesion, as seen on the CAG; 4) patients who previously underwent CABG.
2.2. Blood sampling and coronary angiography Immediately before coronary angiography, a blood sample was obtained from each patient through the introducer sheath that was placed in the femoral artery, and this sample was aliquoted in a 10 ml sterile tube (anticoagulant: EDTA) and then processed within 30 min. Standard angiography, with ≥ 4 views of the left coronary system and 2 views of the right coronary artery, was used for interpretation. The collateral scoring system we used was modified from the previously described Thrombolysis In Myocardial Infarction Scoring System [2]. The ranking from 0 to 2 was based on the presence of collateral vessels and opacification of the recipient vessel. A grade of 0 was given for no visible collaterals, a grade of 1 was given for visible collaterals, but there was no filling of the recipient epicardial vessels, and a grade of 2 was given for filling (partial or complete) of the recipient epicardial vessels by the collaterals. A separate angiographer, who was blinded to the initial reading, reviewed the angiograms. For the cases of disagreement, a third angiographer, who was blinded to the initial two readings, served as an arbitrator. 2.3. Measurement of growth factors The whole blood samples were centrifuged at 3000 rpm for 10 min at room temperature. The plasma supernatant was removed, frozen in liquid nitrogen and then stored at − 80 °C in aliquots that were used for the growth factor level assays. Standard enzyme-linked immunosorbent assay kits (R&D Systems, Inc., USA) were used to determine the plasma growth factor levels of VEGF, endostatin, MCP-1 and SDF-1. 2.4. Data collection and statistical analysis The clinical data was obtained from a comprehensive review of each patient's medical record and with using the established criteria for hypertension, diabetes mellitus, hyperlipidemia and myocardial infarction. Current smoking was defined as the active use of tobacco products at the time of enrollment into the study. Analysis between groups for statistically significant differences in the categorical data was performed using the chi-square test. The continuous variables are presented as mean ± standard deviation (SD), and they were compared by Student's T test. A p value below 0.05 was considered statistically significant. 3. Results 3.1. Baseline characteristics and the cardiac enzymes Table 1 summarizes the patient's profiles and the cardiac enzymes by the group. The mean age and the proportion of patients with angina or prior MI were higher in the group with well-developed collateral circulation, but the differences
H.-J. Park et al. / International Journal of Cardiology 130 (2008) 409–413 Table 1 Baseline characteristics and cardiac enzymes
Clinical variables Age, years Male, n (%) Hypertension, n (%) Diabetes, n (%) Smoking, n (%) Hyperlipidemia, n (%) Angina, n (%) Prior MI, n (%) Prior PCI, n (%) Duration from onset of chest pain, (days) Cardiac enzymes CK-MBinitial (ng/ml) CK-MBpeak (ng/ml) Troponin Iinitial (ng/ml) Troponin Ipeak (ng/ml)
Table 2 Angiographic characteristics
Collateral (−) (N = 20)
Collateral (+) (N = 20)
p
57 ± 12 14 (70) 12 (60) 8 (40) 10 (50) 9 (45) 5 (25) 0 (0) 1 (5) 3.5 ± 2.3
64 ± 13 12 (60) 15 (75) 8 (40) 12 (60) 9 (45) 6 (30) 1 (5) 1 (5) 3.8 ± 2.2
0.11 0.51 0.31 1.00 0.53 1.00 0.72 0.31 1.00 0.68
Collateral (−)
46.9 ± 55.1 85.9 ± 95.1 16.4 ± 18.5 29.7 ± 21.6
0.66 0.63 0.74 0.18
were not statistically meaningful. The mean duration from the onset of chest pain to CAG was not different between the two groups. Although the levels of cardiac enzymes such as CKMB and troponin I were lower in the group with welldeveloped collateral circulation than those levels in the other
Collateral (+)
p
Number of diseased vessels a 1, n (%) 9 (45) 2, n (%) 4 (20) 3, n (%) 7 (30)
5 (25) 7 (35) 8 (40)
0.36
Location of culprit lesions LAD, n (%) 8 (40) LCX, n (%) 5 (25) RCA, n (%) 7 (35)
11 (55) 0 (0) 9 (45)
0.06
Number of totally occluded culprit lesions, n (%) 6 (30) 17 (85) a
55.3 ± 64.0 99.3 ± 79.4 18.4 ± 18.9 38.4 ± 17.8
411
b0.001
Defined as N50% stenosis of the lesion according to the angiography.
group, there were no statistically significant differences between them. 3.2. Comparison between the group with the absent collateral circulation and the group with well-developed collateral circulation Fig. 1A shows the representative coronary angiography for a patient with markedly visible collaterals during the early phase of AMI. Although his left anterior descending
Fig. 1. The difference of collateral response between the individual patients. (A) shows a representative coronary angiography for a patient with marked visible collaterals during the early phase of AMI. Although his left anterior descending artery was totally occluded, it was well filled by collaterals that arose from the right coronary artery. On the other hand, (B) shows the coronary angiography for a patient without visible collaterals. Despite total occlusion of the left circumflex artery, there were no visible collaterals on the CAG.
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Fig. 2. Comparison of growth factors between the group without well-developed collateral circulation and the group with well-developed collateral circulation.
artery was totally occluded, it was well filled by collaterals that arose from the right coronary artery. On the other hand, Fig. 1B shows the coronary angiography for a patient without visible collaterals. Despite total occlusion of the left circumflex artery, there were no visible collaterals noted on the CAG. Table 2 shows the angiographic characteristics according to the group. The proportion of patients with more than two-vessel disease was higher in the group with a score of 2 compared to that of the group with a score of 0. However, the number of diseased vessels and the location of the culprit lesions were not statistically different on comparisons between the two groups. There was a significant difference in the number of totally occluded culprit lesions (score 0: n = 6, score 2: n = 17, p b 0.001). Fig. 2 shows the plasma levels of several growth factors according to the group. The plasma MCP-1 levels were significantly higher in the group with a score of 2 compared to those levels of the patients in the group with a score of 0 (262 ± 216 pg/ml vs. 151 ± 88, p = 0.043). However, the plasma levels of VEGF, endostatin and SDF-1 were not different on comparisons between the groups (VEGF; 369 ± 377 vs. 324 ± 363 pg/ml, endostatin; 1.74 ± 1.71 vs. 1.49 ± 1.15 ng/ml, SDF-1; 1806 ± 508 vs. 2091 ± 772 pg/ml, respectively). 4. Discussion The present study shows that plasma levels of MCP-1 were significantly increased in the patients with visible collaterals during the early phase of AMI, as compared with those patients without visible collaterals during the early phase of AMI. However, the plasma levels of VEGF, endostatin and SDF-1 were not different between the two groups. These findings suggest that MCP-1 may play an
important role in the development of collaterals during the early phase of AMI. 4.1. The collateral response during the early phase of AMI As observed in many cases, the collateral growth of an individual may vary from complete to absent during the early phase of AMI. The clinical or environmental factors that influence the development of coronary collaterals in patients with coronary artery disease are the severity of stenosis and the duration of the myocardial ischemic symptoms [13,14]. However, few studies have been conducted to investigate the association between collateral formation and cytokines during the early phase of AMI in human. There are different regulatory mechanisms and associated growth factors involved in the formation of coronary collaterals [6–12]. Immediately after occlusion of a coronary artery, the blood flow is redistributed through the preexisting arterioles that connect a high-pressure area to a low-pressure area. This results in an increased flow velocity and also shear stress in the preexisting arterioles, which activates the endothelium. The activated endothelium of the preexisting arterioles upregulates MCP-1 production and the expression of adhesion molecules. It has been observed that the targeted disruption of the MCP-1 receptor in mice prevents all collateral growth [15] but an infusion of MCP-1 into the proximal stump of the occluded femoral artery led to strong arteriogenesis [16]; this suggests that monocyte recruitment and activation, and the upregulation of MCP-1 seem to be very important for the promotion of arteriogenesis. VEGF has been reported to contribute to arteriogenesis, and VEGF affects monocyte chemotaxis via the VEGF receptor-1 [17,18] and it increases endothelial adhesion and transmi-
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gration of monocytes [19]. However, as was shown in our study on comparing the plasma levels of MCP-1 and VEGF according to the grade of collateral development during the early phase of AMI, VEGF did not significantly contribute to the development of visible collaterals, although MCP-1 enhanced arteriogenesis. Endostatin and SDF-1 are other potent factors affecting collateral formation, and these factors may influence arteriogenesis in AMI patients. Endostatin is an antiangiogenic factor and it has been reported to modulate coronary collateral formation in patients with ischemic heart disease [20]. It is interesting that endostatin is increased in patients with AMI before reperfusion therapy as compared with that of the control subjects and it is significantly decreased after reperfusion [21]. While SDF-1 is known to be the ligand for the G-protein coupled receptor CXCR4 and mediate its effect through recruitment of endothelial progenitor cells [22], some studies have reported that SDF1 is significantly upregulated in tissues that are derived from an area of collaterals after acute hindlimb ischemia in mice [23], and systemically administered SDF-1 could enhance arteriogenesis, at least in part, via its direct effects on the endothelium of preexisting arterioles in a rat model of vascular insufficiency [24]. However, we did not find any association between the plasma levels of endostatin and SDF-1 and the development of visible collaterals during the early phase of AMI. Further large scale studies will be required to elucidate the role of endostatin and SDF-1 in the formation of visible collaterals during the early phase of AMI. 4.2. Study limitations First, we did not examine the plasma levels of growth factors in the normal controls and we could not compare these between the patients with AMI and the controls. Second, several growth factors and cytokines are produced locally in ischemic cardiac tissue and they are lower in the systemic circulation because of dilution upon washout. In this study, we used the plasma of arterial samples to measure the concentration of growth factors, and this type of plasma is subject to the influence of washout and so it may not necessarily demonstrate a gradient. References [1] Ishihara M, Inoue I, Kawagoe T, et al. Comparison of the cardioprotective effect of prodromal angina pectoris and collateral circulation in patients with a first anterior wall acute myocardial infarction. Am J Cardiol 2005;95:622–5. [2] Habib GB, Heibig J, Forman SA, et al. Influence of coronary collateral vessels on myocardial infarct size in human. Results of phase I Thrombolysis In Myocardial Infarction (TIMI) trial. The TIMI Investigators. Circulation 1991;83:739–46. [3] Sabia PJ, Powers ER, Ragosta M, Sarembock IJ, Burwell LR, Kaul S. An association between collateral blood flow and myocardial viability in patients with recent myocardial infarction. N Engl J Med 1992;327: 1825–31.
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