BioMed Research International
Volume 2019 (2019), Article ID 4834202, 8 pages
https://doi.org/10.1155/2019/4834202

Review Article

The Biochemical Markers Associated with the Occurrence of Coronary Spasm

Liang Li, Yong-Ping Jin, Shu-Dong Xia, and Chao Feng

Department of Cardiology, The Fourth Affiliated Hospital of Zhejiang University, Yiwu, China

Correspondence should be addressed to Chao Feng; 8013010@zju.edu.cn

Received 29 May 2019; Revised 28 July 2019; Accepted 9 August 2019; Published 17 September 2019

Academic Editor: Nazario Carrabba

Copyright © 2019 Liang Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

Coronary artery spasm (CAS) is one of the mechanisms of angina pectoris. Unlike the diagnosis of acute myocardial infarction which is based on the elevation of cardiac markers, the diagnosis of CAS is difficult and sometimes requires sophisticated and risky provocative test which is not widely accepted in China. There is no well-established biomarker for the diagnosis or prediction of CAS. However, there are some biomarkers proven to be associated with the occurrence of CAS. For example, inflammatory factors including C-reactive protein and cytokines, lipoprotein (a), and cystatin-C might be precipitating factor for CAS. Rho-kinase as a mediator involved in multiple mechanisms of CAS, serotonin, and endothelin-1 as powerful vasoconstrictors leading to vasospasm were all observed being elevated in patients with CAS. Thioredoxin and nitrotyrosine reflected the oxidative status and could be observed to be elevated after the occurrence of CAS. In some cases doubted to be CAS without the evidence of provocative test, the blood test for the biomarkers mentioned above could be useful for the diagnosis of CAS.

1. Background

Coronary artery spasm (CAS) is a transient and reversible vasoconstriction of epicardial coronary artery or coronary microvessel which leads to transient ischemia. CAS is one of the mechanisms of angina pectoris and is not accompanied by the increase of myocardial oxygen demand. Since 1959 when Prinzmetal et al., first described this particular form of angina occurring at rest with ST-segment elevation on electrocardiogram, the pathogenesis of CAS has been studied for decades. Now it is widely believed that the hyper-reactivity of smooth muscle cells (SMC) in coronary arteries to vasoconstrictor agents is the key pathogenesis of CAS. The activity of SMC to vasoconstrictors or the tone of SMC is regulated via complicated mechanisms which involve endothelial function, oxidative stress, eNOS, Rho-kinase activity, and inflammation. Calcium channel blockers (CCB) has been proved to be effective for most CAS. However, unlike the diagnosis of acute myocardial infarction which is based on the elevation of cardiac markers and is accurate and relatively easy to perform, the diagnosis of CAS is not that easy and sometimes need sophisticated and risky provocative approaches. In China, most of the diagnosis of CAS is only based on the history of typical attack of nocturnal or resting angina without provocative tests because of its risk, thus a lot of patients might be misdiagnosed or underdiagnosed. There’s no well-established biochemical marker which could be used to identify or predict the occurrence or forthcoming CAS, however, there are some markers which had been proven to indicate a higher possibility of CAS. In this paper, the authors reviewed the markers which had been reported to be associated with the occurrence of CAS and sought to make a conclusion of their association with CAS and reliability of their potential use in the diagnosis of CAS.

2. Inflammatory Markers

The role of chronic vascular inflammation in atherosclerosis has been established by many studies [1–7]. The elevation of inflammatory markers has been observed in a series of vascular diseases including coronary artery disease, ischemic stroke, and peripheral artery disease [8–18]. C-reaction protein (CRP) was the most common biomarker used to determine the inflammatory status of vascular disease [19]. Some other markers including cytokines, monocyte count, MPO, sCD40L, and MMPs were all reported to be associated with the inflammatory status of atherosclerosis [20].

Inflammation was also widely believed to be potential stimulant of CAS. Post-mortem and animal studies showed the accumulation of inflammatory cells in coronary vasospastic segments [21, 22]. In a recent study, with 18F-FDG PET-CT, Hiroaki Shimokawa, et al. demonstrated that the inflammation in the adventitia and perivascular adipose tissue was more significant in CAS patients [23]. In clinical studies, the elevation of inflammatory markers was also reported, including CRP, IL-6, sCD40L, monocytes and polymorphonuclear neutrophils [24–27]. CRP and sCD40L were reported to be correlated with the presence of both epicardial and microvascular spasm [27]. The specific role of inflammation in the pathogenesis of CAS still remains to be elucidated. Some studies showed that chronic inflammation suppresses the endothelial function and NO activity [28]. Some cytokines including TNF and IL-1 might enhance the expression and activity of RhoA, and lead to the over-sensitization of Ca2+ through the activation of ROCK pathway [29–31].

However, the specificity of inflammation markers in identification of CAS was weak because inflammation is a common predisposing factor for various vascular diseases. A clinical study showed that the plasma hs-CRP was equally increased in both CAS and CAD groups [32]. Besides, as mentioned above, in the study conducted by Hiroaki Shimokawa the results showed that inflammation in the adventitia and perivascular adipose tissue was significant [23], yet it is not clear whether the systemic inflammation was a precipitating factor for CAS or only the local/adjacent inflammatory stimulant contributes to the occurrence of CAS. Furthermore, the results about the predictive value of some inflammatory markers were not totally consistent among clinical studies. For example, although CRP is reported to be associated with CAS by various studies, a Korean study showed that there was no difference of the levels of CRP between patients with and without CAS, while the peripheral monocyte count is an independent marker for predicting CAS [33]. Anyway, more studies are still required to identify whether some inflammatory marker could be used to discriminate CAS from CAD.

3. Lipoprotein (a)

Hyperlipidemia has been well established as one of the major risk factors of atherosclerotic vascular diseases by overwhelming evidences. The level of low-density lipoprotein (LDL) is now a major therapeutic target for CAD and ischemic stroke. Although the mechanism of CAS is quite different from that of exertional angina which is caused by the accumulation of atherosclerotic plaques or unstable plaques, some studies showed that lipoprotein might also play an important role in the pathogenesis of CAS.

In a clinical study conducted by Keiichi Tsuchida, et al, the results showed that serum lipoprotein (a) concentration was significantly higher in those patients who had a higher basal tone at the spastic site of coronary arteries and required a significantly lower ergonovine dose to provoke spasm [34]. Similarly, Masami Nishino reported that patients with CAS had higher level of lipoprotein (a) compared with those without CAS [35]. Lipoprotein (a) might contribute to the occurrence of CAS through regulating the endothelium function. It was reported that elevated concentration of lipoprotein (a) was correlated to the vasoconstrictor response to Ach and could impair receptor-mediated endothelial vasodilation [36, 37]. In addition, lipoprotein (a) might play a role in the genesis of thrombotic coronary occlusion, therefore leads to the occurrence of AMI subsequent to coronary spasm [38]. However, in a recent large-scale clinical study conducted by Ahmed Mashaly, no relationship between the elevated lipoprotein (a) level and the vasospastic response to the intracoronary Ach provocation test was identified [39]. It suggested that the role of lipoprotein (a) in the pathogenesis in CAS is far from reaching a consensus.

4. Cystatin C

Cystatin C is a cysteine protease inhibitor produced in all nucleated cells and freely infiltrated by the glomeruli. Cystatin C has been proven to be a reliable marker of glomerular filtration rate, especially in the preclinical stage of kidney dysfunction [40]. Two studies in Japan and South Korea showed that a high level of cystatin C was independently associated with the prevalence of CAS, and suggested that cystatin C might be a potential biomarker of CAS [41, 42].

The association between cystatin C and CAS might reflect the role of mild renal dysfunction in the pathogenesis of CAS. It was demonstrated that renal dysfunction could lead to deactivation of endothelial NO synthetase, thus was associated with endothelial dysfunction which was the fundamental mechanism of CAS [43]. Besides, renal dysfunction could cause vascular inflammation, oxidative stress, and atherosclerosis [44], all of which were the contributors of CAS. A clinical study showed that chronic kidney disease stage was a modulator on the association between hs-CRP and CAS. According to the result of this study, the hs-CRP level and monocyte count were associated with CAS independently only in stage 1 of CKD, when the level of cystatin C was a reliable marker [45].

However, just as mentioned before, renal dysfunction especially advanced renal dysfunction was also associated with atherosclerosis and CAD. Studies were still required to identify whether cystatin C could be used as a unique biomarker of CAS differently from CAD.

5. Serotonin

Serotonin (5 H-T) is a well-established vasoactive substance released from aggregating platelets. Since it was discovered in 1930s, a series of studies demonstrated its various roles in vascular disease and neuroscience. Most in vitro studies supported its role as a vasoconstrictor while a few studies suggested in some circumstances, serotonin could be a vasodilator [46]. In normal coronary artery system, serotonin has vasodilating effect; when the endothelium is damaged, infused serotonin could lead to strong vasoconstricting effect or spasm as proved by in vitro study [47, 48]. An early clinical study showed that patients with CAS had higher level of serotonin than controls [49]. Another small-size clinical study showed that the level of serotonin was significantly higher in patients with CAS than that in control even during nonischemic interval [50]. A recent study showed that the level of serotonin was significantly higher in patients with CAS and unobstructed arteries [51]. It suggested that serotonin could be identified as a predictive marker of CAS including microvascular spasm. However, most of the studies about the role of serotonin in the pathogenesis of CAS were conducted decades ago. More clinical studies were still required to detect the level of serotonin in different stages of CAS.

6. Endothelin-1

Endothelium is the “gatekeeper” of the vessel health. Physiologically, endothelium responds to humoral, neural, and hemodynamic changes, release vasodilators, and leads to coronary dilation. However, under some pathological condition, vasoconstrictors derived from endothelium overcome and lead to coronary spasm [52]. In 1988, endothelin-1 was identified as the first endothelium-derived contractor by Yanagisawa’s group [53]. Since then, endothelin-1 and endothelial dysfunction have been the focus of CAS-associated research. Matsuyama showed that the level of endothelin-1 was increased in the coronary sinus during spasm [54]. Kaski and Hoffmann showed that the concentration of circulating plasma endothelin-1 level was raised in patients with CAS in their respective studies [55, 56]. Toyo-oka found that the level of endothelin-1 was significantly higher in spasm-provoked patients than that in nonprovoked patients, and was transiently decreased to normal after spasm resolved [57]. Kyriakides confirmed that endothelin-1 contributed to the total vasomotor tone mostly mediated by ET-A receptor [58]. In a case reported by Vermeltfoort, the treatment with endothelin receptor antagonist bosentan successfully reduced the frequency and severity of chest pain in a patient with CAS [59]. The experiment on porcine model also demonstrated that administration of ET-A receptor antagonist is effective to prevent CAS [60]. Now endothelin-1 is widely believed to be one of the most potent endogenous vasoconstrictors which could initiate and maintain both epicardial and microvascular spasm.

Based on the results of the studies above, endothelin-1 could be identified as a potential marker for the identification or even prediction of CAS. However, the sensitivity and specificity of endothelin-1 in the identification of CAS might be limited. As a powerful vasoactive factor, endothelin-1 is also associated with atherosclerosis, pulmonary hypertension, hypertension, and renal failure [61]. Besides, it was reported that the plasma level of endothelin-1 was only 1/100 of that within the vascular wall [62]. Therefore the change of endothelin-1 level tested by serum test might not reflect the pathological change of the vessels directly. Third, it was reported that endothelin-1 could augment the vasoconstriction caused by other substances. Even low concentration of endothelin-1 might lead to spasm through its contractile response to serotonin and norepinephrine [63].

7. Neuropeptide Y

Neuropeptide Y is a bioactive peptide released from sympathetic nervous system along with norepinephrine after sympathetic stimulation, and acts as a co-transmitter and local neuromodulator of several aspects of cardiac function. Neuropeptide has been studied as a potent vasoactive factor for decades. In 1985, Aizawa’s group found that the administration of neuropeptide Y resulted in vasoconstriction of canine coronary artery in a dose-response model [64]. They also identified that calcium-channel blockers could attenuate the vasoconstrictor action of Neuropeptide Y [65]. Preito demonstrated that neuropeptide Y induced the contraction of distal coronary arteries more significantly than that of the proximal epicardial arteries of rats [66]. Later for the first time in clinical trials Clarke showed that the infusion of neuropeptide Y lead to transient typical chest pain and electrocardiographic change in patients without significant coronary stenosis and confirmed the constriction of small vessels rather than epicardial arteries caused by neuropeptide Y by arteriography [67]. Recently, more clinical studies identified that endogenous neuropeptide-Y could cause coronary artery constriction especially coronary microvascular spasm, in both patients without coronary stenosis and patients of ST-elevated myocardial infarction [68–70].

However, by now neuropeptide is mostly studied in the background of high sympathetic drive such as myocardial infarction and hyperventilation test. Few studies compared the basic level of neuropeptide between patients with and without CAS. Although its significant correlation with coronary microvascular spasm has been confirmed, it is still very far away from identifying it as a biomarker to predict or identify the presence of coronary microvascular spasm.

8. Rho-kinase

Rho-kinase is one of the downstream targets of GTP-binding protein Rho [71]. Previous studies demonstrated that Rho-kinase played a pivotal role in the regulation of many cellular functions and in the pathogenesis of vascular disease [72]. The impact of Rho-kinase activity in CAS was also reported by several clinical studies. Kikuchi demonstrated that Rho-kinase activity in circulating neutrophils determined by the extent of phosphorylation of myosin-binding submits was significantly higher in CAS group than that in control. Besides, after treatment with CCB, Rho-kinase activity was significantly decreased in CAS group [73]. It suggested that Rho-kinase activity in circulating neutrophils could be a useful biomarker of both diagnosis and disease activity assessment of CAS. Later a study in Taiwan also showed that leukocyte Rho-kinase activity predicted the presence and severity of CAS [74]. Another study proved that the activity of Rho-kinase had a distinct circadian variation with a peak in the morning, strongly associated with coronary basal tone and vasoconstriction [75].

Actually, long before that it has been reported CAS including coronary microvascular spasm could be suppressed by fasudil which is a well-established inhibitor of Rho-kinase [76, 77]. Some animal studies demonstrated that Rho-kinase could inhibit the myosin-binding subunit of myosin phosphate, then enhance the phosphorylation of myosin light chain and lead to vasospasm [78]. In addition, Rho-kinase could also mediate hypoxia-induced down-regulation of endothelial NO synthase, vascular SMC proliferation and migration, the monocyte adhesion and spreading on endothelium [72, 79, 80]. Thus, Rho-kinase may be a crucial mediator of endothelial function, NO synthase, and inflammation, all of which are involved in the pathogenesis of CAS. Based on the animal and clinical studies, Rho-kinase activity might become a promising biomarker of CAS, if the measurement could be more simplified.

9. Oxidative Stress Markers

Oxidative stress has been identified as a key factor involved in a series of pathological changes including aging, degeneration, cancer, and vascular disease as well. Vascular oxidative stress and subsequent increase of reactive oxygen species (ROS) were proven to be contributors to vascular dysfunction and atherothrombosis through the impairment of endothelial function [81, 82]. There is growing evidence showing that oxidative stress is associated with the occurrence and severity of CAS, and suggest that some oxidative stress markers might be potential biomarkers of CAS [83, 84].

Oxidized-LDL is the oxidized product of LDL and a well-established marker of oxidative distress. The oxidization of LDL leads to the formation of foam cells, proliferation of SMC, and also activation of inflammation. Besides, oxidized-LDL was proven to be an independent determinant of coronary macrovasomotor and microvasomotor responses which were associated with CAS [85]. In a small clinical study, Kugiyama K1 reported that the oxidized-LDL levels in patients with CAS were significantly higher than those in controls and suggested a significant and positive correlation between oxidized-LDL and the vasoconstrictor response of coronary arteries to Ach and impaired vasodilation of endothelium [84]. Malondialdehyde-Modified-LDL as a form of oxidized-LDL was also reported to be associated with the occurrence of CAS [86]. However, the role of oxidized-LDL in the diagnosis the CAS is still controversial. In a study carried out by Yamaguchi, the results showed that the increase of plasma TG-rich lipoproteins and their remnants were more significant markers of CAS than of CAD, while the increase of plasma oxidized-LDL was equal for both CAS and CAD [32].

Thioredoxin is small protein consisting of a redox-active dithiol/disulfide in the active side which functions as an important oxidoreductase widely involved in the defense against excessive generation of reactive oxygen species (ROS) and also in the regulation of fundamental cell functions [87]. The synthesis of thioredoxin is activated under oxidative stress-related conditions such as infections and ischemia [87], and under some chronic vascular disease such as hypertension and atherosclerosis as well [88, 89]. Some clinical studies demonstrated that the plasma level of thioredoxin was increased among patients with CAS with the decrease of antioxidant Vitamin E [90, 91]. Besides, the level of thioredoxin was associated with the activity of CAS [90]. However, the elevation of thioredoxin might probably be the result of ischemia-reperfusion caused by CAS, but not the cause of CAS. Therefore, the level of thioredoxin might be used to identify the severity of CAS without any predicting value before the occurrence of CAS.

Nitrotyrosine is generated from the reaction between tyrosine residues and peroxynitrite. As an oxidative stress marker, nitrotyrosine could decrease the bioavailability of NO and the production of prostacyclin, therefore lead to the decrease of vasorelaxation [92, 93]. In a clinical study, the results showed that serum level of nitrotyrosine was significantly increased after the onset of CAS induced by acetylcholine provocation, and suggested that nitrotyrosine could be a potential biomarker for the diagnosis of CAS [94]. However, similarly to thioredoxin, the elevation of nitrotyrosine level is probably the result of CAS-induced ischemia, but not the cause of CAS. Therefore, it could just be used as the marker of the activity of CAS, but not a predictor for the occurrence of CAS.

10. Conclusion

The exploration of the pathogenesis of CAS has lasted for decades. During the exploration, various biochemical markers were studied with several inflammatory markers, oxidative stress markers, lipoprotein (a), cystatin, serotonin, endothelin-1, neuropeptide Y and Rho-kinase identified to be associated with the occurrence of CAS. However, some studies about CRP and lipoprotein (a) showed negative results. We think that the different study design about the time point of blood test before or after the occurrence of CAS, the limited sample size, the difference of races involved in the studies contributed together to the conflicting results. Although the detail of the pathological changes of CAS is not clearly elucidated yet, the roles of the biochemical markers in the pathological changes before and during CAS could be briefly summarized. Inflammation and oxidative stress might be the main background that contributes to the impaired endothelium function and elevated tone of vessels, with lipoprotein (a) and cystatin C also involved in the process of upstream regulation. Rho-kinase might be the key regulator involved in the pathogenesis of CAS. Serotonin and endothelin-1 function as powerful vasoconstrictors and lead to CAS directly. Besides, although the structures of epicardial coronary artery and microvessels are different, the biochemical markers associated with the spasm of different arteries were mostly similar, such as serotonin, endothelin-1, and Rho-kinase. However, neuropeptide Y as a co-transmitter of norepinephrine is the only biochemical marker proven to be associated with microvascular spasm rather than epicardial coronary spasm. It indicates that the pathogenesis associated with epicardial coronary spasm and microvascular spasm might be different to some extent, with the corresponding effective therapies being different too. Among the various biochemical markers associated with the occurrence of CAS, some of them were identified to be elevated after CAS, such as thioredoxin and nitrotyrosine. However, the elevation of them after CAS was not associated with spasm specifically enough. Yet, the blood test for the biomarkers such as serotonin, endothelin-1, Rho-kinase and neuropeptide Y could be useful for the diagnosis of CAS, especially when provocative test is not acceptable or not available. Anyway, more studies are still required to identify their roles and search for new markers for the diagnosis of CAS.

Conflicts of Interest

The authors declare that there is no conflict of interest.

Acknowledgments

This research was supported by grants from the National Natural Science Foundation of China (No. 81600393), the Provincial Natural Science Foundation of Zhejiang (LY15H020003), the Provincial Basic Science and Welfare Research Project of Zhejiang (LGF19H180017) and the Zilong Mountain Young Talent Program of ZJU4H.

References

C. Kasikara, A. C. Doran, B. Cai, and I. Tabas, “The role of non-resolving inflammation in atherosclerosis,” Journal of Clinical Investigation, vol. 128, no. 7, pp. 2713–2723, 2018.

P. Mury, E. N. Chirico, M. Mura, A. Millon, E. Canet-Soulas, and V. Pialoux, “Oxidative stress and inflammation, key targets of atherosclerotic plaque progression and vulnerability: potential impact of physical activity,” Sports Medicine, vol. 48, no. 12, 2018.

P. Raggi, J. Genest, J. T. Giles et al., “Role of inflammation in the pathogenesis of atherosclerosis and therapeutic interventions,” Atherosclerosis., vol. 276, pp. 98–108, 2018.

G. Siasos, A. G. Papavassiliou, and D. Tousoulis, “Editorial: inflammation and atherosclerosis: the role of novel biomarkers (Part-I),” Current Medicinal Chemistry, vol. 22, no. 22, pp. 2616–8, 2015.

B. W. Wong, A. Meredith, D. Lin, and B. M. McManus, “The biological role of inflammation in atherosclerosis,” Canadian Journal of Cardiology, vol. 28, no. 6, pp. 631–641, 2012.

M.-Y. Wu, C.-J. Li, M.-F. Hou, and P.-Y. Chu, “New insights into the role of inflammation in the pathogenesis of atherosclerosis,” International Journal of Molecular Sciences, vol. 18, no. 10, p. 2034, 2017.

H. Yingchun, M. Yahong, W. Jiangping, H. Xiaokui, and Z. Xiaohong, “Increased inflammation, endoplasmic reticulum stress and oxidative stress in endothelial and macrophage cells exacerbate atherosclerosis in ApoCIII transgenic mice,” Lipids in Health and Disease, vol. 17, no. 1, 2018.

G. Brevetti, F. Piscione, P. Cirillo et al., “In concomitant coronary and peripheral arterial disease, inflammation of the affected limbs predicts coronary artery endothelial dysfunction,” Atherosclerosis, vol. 201, no. 2, pp. 440–446, 2008.

M. M. McDermott, J. M. Guralnik, A. Corsi et al., “Patterns of inflammation associated with peripheral arterial disease: the InCHIANTI study,” American Heart Journal, vol. 150, no. 2, pp. 276–281, 2005.

M. Montagnana, C. Fava, E. Arosio et al., “Inflammation and platelet activation in peripheral arterial occlusive disease,” International Journal of Angiology, vol. 16, no. 03, pp. 84–88, 2007.

A. Tuttolomondo, D. Di Raimondo, R. Pecoraro, V. Arnao, A. Pinto, and G. Licata, “Inflammation in ischemic stroke subtypes,” Current Pharmaceutical Design, vol. 18, no. 28, pp. 4289–4310, 2012.

K. Toutouzas, G. Benetos, M. Drakopoulou et al., “Incremental predictive value of carotid inflammation in acute ischemic stroke,” Stroke, vol. 46, no. 1, pp. 272–274, 2015.

S. Shekhar, M. W. Cunningham, M. R. Pabbidi, S. Wang, G. W. Booz, and F. Fan, “Targeting vascular inflammation in ischemic stroke: Recent developments on novel immunomodulatory approaches,” European Journal of Pharmacology, vol. 833, pp. 531–544, 2018.

J. Pei, X. You, and Q. Fu, “Inflammation in the pathogenesis of ischemic stroke,” Frontiers in Bioscience, vol. 20, pp. 772–783, 2015.

M. Ali, S. Girgis, A. Hassan, S. Rudick, and R. C. Becker, “Inflammation and coronary artery disease: from pathophysiology to Canakinumab Anti-Inflammatory thrombosis outcomes study (CANTOS),” Coronary Artery Disease, vol. 29, no. 5, pp. 429–437, 2018.

N. Alie, M. Eldib, Z. A. Fayad, and V. Mani, “Inflammation, atherosclerosis, and coronary artery disease: PET/CT for the evaluation of atherosclerosis and inflammation,” Clinical Medicine Insights: Cardiology, vol. 8, no. Suppl 3, pp. 13–21, 2014.

M. K. Christiansen, S. B. Larsen, M. Nyegaard et al., “Coronary artery disease-associated genetic variants and biomarkers of inflammation,” PloS ONE, vol. 12, no. 7, p. e0180365, 2017.

G. Christodoulidis, T. J. Vittorio, M. Fudim, S. Lerakis, and C. E. Kosmas, “Inflammation in coronary artery disease,” Cardiology in Review, vol. 22, no. 6, pp. 279–288, 2014.

V. Lubrano and S. Balzan, “Consolidated and emerging inflammatory markers in coronary artery disease,” World Journal of Experimental Medicine, vol. 5, no. 1, pp. 21–32, 2015.

K. V. Voudris, J. Chanin, D. N. Feldman, and K. Charitakis, “Novel inflammatory biomarkers in coronary artery disease: potential therapeutic approaches,” Current Medicinal Chemistry., vol. 22, no. 22, pp. 2680–9, 2015.

H. Suzuki, S. Kawai, T. Aizawa et al., “Histological evaluation of coronary plaque in patients with variant angina: relationship between vasospasm and neointimal hyperplasia in primary coronary lesions,” Journal of the American College of Cardiology, vol. 33, no. 1, pp. 198–205, 1999.

K. Nishimiya, Y. Matsumoto, T. Shindo et al., “Association of adventitial vasa vasorum and inflammation with coronary hyperconstriction after Drug-Eluting stent implantation in pigs in vivo,” Circulation Journal, vol. 79, no. 8, pp. 1787–1798, 2015.

K. Ohyama, Y. Matsumoto, K. Takanami et al., “Coronary adventitial and perivascular adipose tissue inflammation in patients with vasospastic angina,” Journal of the American College of Cardiology., vol. 71, no. 4, pp. 414–425, 2018.

J.-J. Li, Y.-P. Zhang, P. Yang et al., “Increased peripheral circulating inflammatory cells and plasma inflammatory markers in patients with variant angina,” Coronary Artery Disease, vol. 19, no. 5, pp. 293–297, 2008.

T. Itoh, Y. Mizuno, E. Harada, M. Yoshimura, H. Ogawa, and H. Yasue, “Coronary spasm is associated with chronic low-grade inflammation,” Circulation Journal, vol. 71, no. 7, pp. 1074–1078, 2007.

A. Mahemuti, K. Abudureheman, F. Schiele et al., “Association between inflammatory markers, hemostatic markers, and traditional risk factors on coronary artery spasm in patients with normal coronary angiography,” Journal of Interventional Cardiology, vol. 27, no. 1, pp. 29–35, 2014.

P. Ong, A. Carro, A. Athanasiadis et al., “Acetylcholine-induced coronary spasm in patients with unobstructed coronary arteries is associated with elevated concentrations of soluble CD40 ligand and high-sensitivity C-reactive protein,” Coronary Artery Disease, vol. 26, no. 2, pp. 126–132, 2015.

B. R. Clapp, A. D. Hingorani, R. K. Kharbanda et al., “Inflammation-induced endothelial dysfunction involves reduced nitric oxide bioavailability and increased oxidant stress,” Cardiovascular Research, vol. 64, no. 1, pp. 172–178, 2004.

R. Singh, B. Wang, A. Shirvaikar et al., “The IL-1 receptor and Rho directly associate to drive cell activation in inflammation,” Journal of Clinical Investigation, vol. 103, no. 11, pp. 1561–1570, 1999.

H. Shimokawa, “Cellular and molecular mechanisms of coronary artery spasm: lessons from animal models,” Japanese Circulation Journal, vol. 64, no. 1, pp. 1–12, 2000.

I. Hunter, H. J. Cobban, P. Vandenabeele, D. J. MacEwan, and G. F. Nixon, “Tumor necrosis factor-alpha-induced activation of RhoA in airway smooth muscle cells: role in the Ca2+ sensitization of myosin light chain20 phosphorylation,” Molecular Pharmacology, vol. 63, no. 3, pp. 714–721, 2003.

H. Yamaguchi, Y. Homma, and S. Handa, “Biochemical markers of vasospastic coronary artery disease,” Nutrition, Metabolism and Cardiovascular Diseases, vol. 13, no. 6, pp. 365–371, 2003.

K. H. Yun, S. K. Oh, E. M. Park et al., “An Increased Monocyte Count Predicts Coronary Artery Spasm in Patients with Resting Chest Pain and Insignificant Coronary Artery Stenosis,” The Korean Journal of Internal Medicine, vol. 21, no. 2, pp. 97–102, 2006.

K. Tsuchida, T. Hori, N. Tanabe et al., “Relationship between serum lipoprotein(a) concentrations and coronary vasomotion in coronary spastic angina,” Circulation Journal, vol. 69, no. 5, pp. 521–525, 2005.

M. Nishino, N. Mori, T. Yoshimura et al., “Higher serum uric acid and lipoprotein(a) are correlated with coronary spasm,” Heart and Vessels, vol. 29, no. 2, pp. 186–190, 2014.

Y. Tsurumi, H. Nagashima, K. Ichikawa, T. Sumiyoshi, and S. Hosoda, “Influence of plasma lipoprotein (a) levels on coronary vasomotor response to acetylcholine,” Journal of the American College of Cardiology, vol. 26, no. 5, pp. 1242–1250, 1995.

V. Schachinger, M. Halle, J. Minners, A. Berg, and A. M. Zeiher, “Lipoprotein(a) selectively impairs receptor-mediated endothelial vasodilator function of the human coronary circulation,” Journal of the American College of Cardiology, vol. 30, no. 4, pp. 927–934, 1997.

K. Miwa, K. Nakagawa, N. Yoshida, Y. Taguchi, and H. Inoue, “Lipoprotein(a) is a risk factor for occurrence of acute myocardial infarction in patients with coronary vasospasm,” Journal of the American College of Cardiology, vol. 35, no. 5, pp. 1200–1205, 2000.

A. Mashaly, S. W. Rha, B. G. Choi et al., “Impact of serum lipoprotein(a) on endothelium-dependent coronary vasomotor response assessed by intracoronary acetylcholine provocation,” Coronary Artery Disease, vol. 29, no. 6, pp. 516–525, 2018.

E. J. Lamb, “Cystatin C: why clinical laboratories should be measuring it,” Annals of Clinical Biochemistry, vol. 52, no. 6, pp. 709–711, 2015.

A. Funayama, T. Watanabe, T. Tamabuchi et al., “Elevated cystatin C levels predict the incidence of vasospastic angina,” Circulation Journal, vol. 75, no. 10, pp. 2439–2444, 2011.

S. N. Lee, D. I. Shin, M. H. Jung et al., “Impact of cystatin-C level on the prevalence and angiographic characteristics of vasospastic angina in korean patients,” International Heart Journal, vol. 56, no. 1, pp. 49–55, 2015.

S. Koga, S. Ikeda, T. Nakata et al., “Low Glomerular Filtration Rate Is Associated With High Prevalence of Vasospastic Angina,” Circulation Journal, vol. 75, no. 7, pp. 1691–1695, 2011.

G. A. Kaysen and J. P. Eiserich, “The role of oxidative stress-altered lipoprotein structure and function and microinflammation on cardiovascular risk in patients with minor renal dysfunction,” Journal of the American Society of Nephrology, vol. 15, no. 3, pp. 538–548, 2004.

H. J. Hsu, C. H. Yen, K. H. Hsu et al., “Chronic kidney disease stage Is a modulator on the association between high-sensitivity C-Reactive protein and coronary vasospastic angina,” The Scientific World Journal, vol. 2014, pp. 1–9, 2014.

S. W. Watts, “Oh,the places you'll go! My many colored serotonin (apologies to Dr. Seuss),” American Journal of Physiology-Heart and Circulatory Physiology, vol. 311, no. 5, pp. H1225–H1233, 2016.

P. Golino, F. Piscione, J. T. Willerson et al., “Divergent effects of serotonin on coronary-artery dimensions and blood flow in patients with coronary atherosclerosis and control patients,” New England Journal of Medicine, vol. 324, no. 10, pp. 641–648, 1991.

E. P. McFadden, J. G. Clarke, G. J. Davies, J. C. Kaski, A. W. Haider, and A. Maseri, “Effect of intracoronary serotonin on coronary vessels in patients with stable angina and patients with variant angina,” The New England journal of medicine, vol. 324, no. 10, pp. 648–54, 1991.

J. Figueras, E. Domingo, J. Cortadellas et al., “Comparison of plasma serotonin levels in patients with variant angina pectoris versus healed myocardial infarction,” The American Journal of Cardiology, vol. 96, no. 2, pp. 204–207, 2005.

Y. Murakami, Y. Ishinaga, K. Sano et al., “Increased serotonin release across the coronary bed during a nonischemic interval in patients with vasospastic angina,” Clinical Cardiology, vol. 19, no. 6, pp. 473–476, 1996.

Y. Odaka, J. Takahashi, R. Tsuburaya et al., “Plasma concentration of serotonin is a novel biomarker for coronary microvascular dysfunction in patients with suspected angina and unobstructive coronary arteries,” European Heart Journal., vol. 38, no. 7, p. ehw448, 2017.

P. A. Cahill and E. M. Redmond, “Vascular endothelium – Gatekeeper of vessel health,” Atherosclerosis, vol. 248, pp. 97–109, 2016.

M. Yanagisawa, A. Inoue, T. Ishikawa et al., “Primary structure, synthesis, and biological activity of rat endothelin, an endothelium-derived vasoconstrictor peptide.,” Proceedings of the National Academy of Sciences, vol. 85, no. 18, pp. 6964–6967, 1988.

K. Matsuyama, H. Yasue, K. Okumura et al., “Increased plasma level of endothelin-1-like immunoreactivity during coronary spasm in patients with coronary spastic angina,” The American Journal of Cardiology, vol. 68, no. 10, pp. 991–995, 1991.

J. C. Kaski, P. M. Elliott, O. Salomone et al., “Concentration of circulating plasma endothelin in patients with angina and normal coronary angiograms,” Heart J., vol. 74, no. 6, pp. 620–624, 1995.

E. Hoffmann, P. Assennato, M. Donatelli, I. Colletti, and T. M. Valenti, “Plasma endothelin-1 levels in patients with angina pectoris and normal coronary angiograms,” American Heart Journal, vol. 135, no. 4, pp. 684–688, 1998.

T. Toyo-oka, T. Aizawa, N. Suzuki et al., “Increased plasma level of endothelin-1 and coronary spasm induction in patients with vasospastic angina pectoris.,” Circulation, vol. 83, no. 2, pp. 476–483, 1991.

Z. S. Kyriakides, D. T. Kremastinos, E. Bofilis, D. Tousoulis, A. Antoniadis, and D. J. Webb, “Endogenous endothelin maintains coronary artery tone by endothelin Type A receptor stimulation in patients undergoing coronary arteriography,” Heart., vol. 84, no. 2, pp. 176–182, 2000.

I. A. Vermeltfoort, P. G. Raijmakers, and P. W. Kamphuisen, “Improved myocardial perfusion preceding clinical response on bosentan treatment for coronary vasospasm,” Acta Cardiologica., vol. 64, no. 3, pp. 415–417, 2009.

T. Osugi, S. Saitoh, K. Matumoto et al., “Preventive effect of chronic endothelin Type A receptor antagonist on coronary microvascular spasm induced by repeated epicardial coronary artery endothelial denudation in pigs,” Journal of Atherosclerosis and Thrombosis, vol. 17, no. 1, pp. 54–63, 2010.

E. Thorin and D. J. Webb, “Endothelium-derived endothelin-1,” Pflügers Archiv- European Journal of Physiology, vol. 459, no. 6, pp. 951–958, 2010.

R. M. Kedzierski and M. Yanagisawa, “Endothelin system: the double-edged sword in health and disease,” Annu Rev Pharmacol Toxicol., vol. 41, pp. 851–76, 2001.

E. Thorin, T. D. Nguyen, and A. Bouthillier, “Control of vascular tone by endogenous endothelin-1 in human pial arteries,” Stroke, vol. 29, no. 1, pp. 175–180, 1998.

Y. Aizawa, M. Murata, M. Hayashi, T. Funazaki, S. Ito, and A. Shibata, “Vasoconstrictor effect of neuropeptide Y (NPY) on canine coronary artery,” Japanese Circulation Journal, vol. 49, no. 6, pp. 584–588, 1985.

M. Hayashi, Y. Aizawa, M. Satoh, K. Suzuki, and A. Shibata, “Effect of nifedipine on neuropeptide Y-induced coronary vasoconstriction in anesthetized dogs,” Japanese Heart Journal, vol. 27, no. 2, pp. 251–257, 1986.

D. Prieto, S. Benedito, U. Simonsen, and N. C. Nyborg, “Regional heterogeneity in the contractile and potentiating effects of neuropeptide Y in rat isolated coronary arteries: modulatory action of the endothelium,” British Journal of Pharmacology, vol. 102, no. 3, pp. 754–758, 1991.

J. G. Clarke, G. J. Davies, R. Kerwin et al., “Coronary artery infusion of neuropeptide Y in patients with angina pectoris,” The Lancet, vol. 329, no. 8541, pp. 1057–1059, 1987.

G. M. C. Rosano, D. Tousoulis, E. McFadden, J. Clarke, G. J. Davies, and J. C. Kaski, “Effects of neuropeptide Y on coronary artery vasomotion in patients with microvascular angina,” International Journal of Cardiology, vol. 238, pp. 123–127, 2017.

N. Herring, N. Tapoulal, M. Kalla et al., “Neuropeptide-Y causes coronary microvascular constriction and is associated with reduced ejection fraction following ST-elevation myocardial infarction,” European Heart Journal, vol. 40, no. 24, pp. 1920–1929, 2019.

F. Cuculi, N. Herring, A. R. De Caterina et al., “Relationship of plasma neuropeptide Y with angiographic, electrocardiographic and coronary physiology indices of reperfusion during ST elevation myocardial infarction,” Heart, vol. 99, no. 16, pp. 1198–1203, 2013.

T. Ishizaki, M. Maekawa, K. Fujisawa et al., “The small GTP-binding protein Rho binds to and activates a 160 kDa Ser/Thr protein kinase homologous to myotonic dystrophy kinase.,” The EMBO Journal, vol. 15, no. 8, pp. 1885–1893, 1996.

H. Shimokawa, S. Sunamura, and K. Satoh, “RhoA/Rho-Kinase in the cardiovascular system,” Circulation Research, vol. 118, no. 2, pp. 352–366, 2016.

Y. Kikuchi, S. Yasuda, K. Aizawa et al., “Enhanced Rho-Kinase activity in circulating neutrophils of patients with vasospastic angina,” Journal of the American College of Cardiology, vol. 58, no. 12, pp. 1231–1237, 2011.

M.-J. Hung, W.-J. Cherng, M.-Y. Hung et al., “Increased leukocyte Rho-associated coiled-coil containing protein kinase activity predicts the presence and severity of coronary vasospastic angina,” Atherosclerosis, vol. 221, no. 2, pp. 521–526, 2012.

T. Nihei, J. Takahashi, R. Tsuburaya et al., “Circadian variation of Rho-Kinase activity in circulating leukocytes of patients with vasospastic angina,” Circulation Journal, vol. 78, no. 5, pp. 1183–1190, 2014.

A. Masumoto, M. Mohri, H. Shimokawa, L. Urakami, M. Usui, and A. Takeshita, “Suppression of coronary artery spasm by the Rho-kinase inhibitor fasudil in patients with vasospastic angina,” Circulation., vol. 105, no. 13, pp. 1545–1547, 2002.

M. Mohri, H. Shimokawa, Y. Hirakawa, A. Masumoto, and A. Takeshita, “Rho-kinase inhibition with intracoronary fasudil prevents myocardial ischemia in patients with coronary microvascular spasm,” Journal of the American College of Cardiology, vol. 41, no. 1, pp. 15–19, 2003.

J. K. Liao, M. Seto, and K. Noma, “Rho kinase (ROCK) inhibitors,” Journal of Cardiovascular Pharmacology, vol. 50, no. 1, pp. 17–24, 2007.

M. Takemoto, J. Sun, J. Hiroki, H. Shimokawa, and J. K. Liao, “Rho-kinase mediates hypoxia-induced downregulation of endothelial nitric oxide synthase,” Circulation, vol. 106, no. 1, pp. 57–62, 2002.

B. Wojciak-Stothard, L. Williams, and A. J. Ridley, “Monocyte adhesion and spreading on human endothelial cells is dependent on Rho-regulated receptor clustering,” The Journal of Cell Biology, vol. 145, no. 6, pp. 1293–1307, 1999.

Y. Higashi, K. Noma, M. Yoshizumi, and Y. Kihara, “Endothelial function and oxidative stress in cardiovascular diseases,” Circulation Journal, vol. 73, no. 3, pp. 411–418, 2009.

Z. S. Nedeljkovic, N. Gokce, and J. Loscalzo, “Mechanisms of oxidative stress and vascular dysfunction,” Postgraduate Medical Journal, vol. 79, no. 930, pp. 195–200, 2003.

Y. Hoshino, S. Yamada, S.-I. Saitoh et al., “Age-related oxidant stress with senescence marker protein-30 deficiency plays a pivotal role in coronary artery spasm,” Coronary Artery Disease, vol. 24, no. 2, pp. 110–118, 2013.

K. Kugiyama, S. Sugiyama, H. Soejima et al., “Increase in plasma levels of oxidized low-density lipoproteins in patients with coronary spastic angina,” Atherosclerosis, vol. 154, no. 2, pp. 463–467, 2001.

T. Matsumoto, H. Takashima, N. Ohira et al., “Plasma level of oxidized low-density lipoprotein is an independent determinant of coronary macrovasomotor and microvasomotor responses induced by bradykinin,” Journal of the American College of Cardiology, vol. 44, no. 2, pp. 451–457, 2004.

T. Oumi, T. Nozato, A. Sakakibara et al., “Malondialdehyde-modified low density lipoprotein as oxidative-stress marker in vasospastic angina patients,” International Heart Journal, vol. 58, no. 3, pp. 335–343, 2017.

J. Lu and A. Holmgren, “The thioredoxin antioxidant system,” Free Radical Biology and Medicine, vol. 66, pp. 75–87, 2014.

D. F. Mahmood, A. Abderrazak, K. El Hadri, T. Simmet, and M. Rouis, “The thioredoxin system as a therapeutic target in human health and disease,” Antioxidants & Redox Signaling, vol. 19, no. 11, pp. 1266–1303, 2013.

T. Ebrahimian and R. M. Touyz, “Thioredoxin in vascular biology: role in hypertension,” Antioxidants & Redox Signaling, vol. 10, no. 6, pp. 1127–1136, 2008.

S. Miyamoto, H. Kawano, T. Sakamoto et al., “Increased Plasma Levels of Thioredoxin in Patients with Coronary Spastic Angina,” Antioxidants & Redox Signaling, vol. 6, no. 1, pp. 75–80, 2004.

K. Miwa, C. Kishimoto, H. Nakamura et al., “Increased oxidative stress with elevated serum thioredoxin level in patients with coronary spastic angina,” Clinical Cardiology, vol. 26, no. 4, pp. 177–181, 2003.

G. Peluffo and R. Radi, “Biochemistry of protein tyrosine nitration in cardiovascular pathology,” Cardiovascular Research, vol. 75, no. 2, pp. 291–302, 2007.

A. J. Kozak, F. Liu, P. Funovics, A. Jacoby, R. Kubant, and T. Malinski, “Role of peroxynitrite in the process of vascular tone regulation by nitric oxide and prostanoids–a nanotechnological approach,” Prostaglandins, Leukotrienes and Essential Fatty Acids, vol. 72, no. 2, pp. 105–113, 2005.

K. Tanabe, Y. Kawai, M. Kitayama et al., “Increased levels of the oxidative stress marker, nitrotyrosine in patients with provocation test-induced coronary vasospasm,” Journal of Cardiology, vol. 64, no. 2, pp. 86–90, 2014.