Myocardial damage, inflammation and thrombin inhibition in unstable coronary artery disease

J Oldgrena,*, L Wallentina, L Gripb, R Linderc, B.L Nørgaardd and A Siegbahne

a Department of Medical Sciences, Cardiology, University Hospital, Uppsala, Sweden
b Department of Cardiology, Sahlgrenska University Hospital, Gothenburg, Sweden
c Department of Cardiology, Karolinska Hospital, Stockholm, Sweden
d Department of Medicine and Cardiology, Aarhus University Hospital, Aarhus, Denmark
e Clinical Chemistry, University Hospital, Uppsala, Sweden

revised April 20, 2003; accepted April 24, 2003 * Correspondence: Jonas Oldgren, MD, Department of Medical Sciences, Cardiology, Uppsala University Hospital, SE-751 85 Uppsala, Sweden


    Abstract
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Aim Unstable coronary artery disease (CAD) is a multifactorial disease involving both thrombotic and inflammatory processes. We have assessed the time-course and the influence of thrombin inhibitors on changes in fibrinogen and C-reactive protein levels, and their relation to myocardial ischaemia in unstable CAD.

Methods and results Three hundred and twenty patients were randomized to 72 h infusion with three different doses of inogatran, a direct thrombin inhibitor, or unfractionated heparin. There were no significant differences between the treatment groups in fibrinogen or C-reactive protein levels. Overall, the fibrinogen levels were significantly increased in the first 24–96 h and still elevated at 30 days. The C-reactive protein levels showed a more pronounced increase during the first 24–96 h, but then markedly decreased over 30 days. Troponin-positive compared to troponin-negative patients had higher fibrinogen and C-reactive protein levels up to 96 h, although there was an increase compared to pre-treatment levels in both groups. A high fibrinogen level (pre-treatment top tertile) was associated with an increased rate of death or myocardial (re-)infarction at 30 days, 13% vs 5.6%, P=0.03, and increased long-term mortality. A high C-reactive protein level was related to increased 30-day mortality, 4% vs 0%, P=0.01.

Conclusion Myocardial cell injury was related to a high degree of inflammation, only some of which is an acutephase response due to tissue damage. The rise in fibrinogen was sustained, which might reflect low grade inflammation with long-term risk of thrombosis. The transient elevation of C-reactive protein levels might indicate a propensity to a pronounced inflammatory response and is associated with increased mortality.

Key Words: Unstable coronary artery disease • inflammation • fibrinogen • C-reactive protein • troponin


    Introduction
 Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Unstable coronary artery disease, i.e. unstableangina or non-Q-wave myocardial infarction, is a multi-factorial disease. Exposure of the thrombogenic contents of a ruptured or fissured atherosclerotic plaque triggers platelet and coagulation activation which may subsequently lead to thrombus formation.1 Furthermore, by destabilizing the atherosclerotic plaque and enhancing thrombus formation, inflammatory processes may also beinvolved in the initiation of unstable coronaryartery disease.2,3 At autopsy, active inflammation is evident by the accumulation of macrophages at sites of the plaque rupture.4 Moreover, elevated levels of interleukins,5 acute-phase proteins,6,7activated circulating monocytes8 and lymphocytes9 have been reported from clinical studies in unstable coronary artery disease.

Fibrinogen is an acute-phase protein directly involved both in platelet aggregation by cross-linking the glycoprotein IIb/IIIa-receptors on adjacent platelets,10 and in the coagulation cascade.11 C-reactive protein, another acute-phase protein, has an unclear biological function, but it has been suggested that C-reactive protein may also interact in the atherosclerotic process by activation of the complement system.12 The early levels of fibrinogen and C-reactive protein have in several studies been identified as indicators of increased short- and long-term risk for adverse clinical outcome in unstable coronary artery disease.7,13–17 There is limited knowledge about the time-course and the influence of anticoagulant treatment of changesin fibrinogen and C-reactive protein in unstable coronary artery disease.7,18,19

The Thrombin Inhibition in Myocardial Ischemia (TRIM) study20 enrolled unstable coronary artery disease patients in Scandinavian centres during 1994 and 1995. The patients were randomized to three different doses of inogatran, a low molecular mass direct thrombin inhibitor,21,22 or standardunfractionated heparin, given as intravenous infusion for 72 h. The aim of the present substudy was to assess the degree of inflammatory activity, as reflected by the course of changes in fibrinogen and C-reactive protein levels in serial plasma samples, the influence of unfractionated heparin or different doses of inogatran on these levels, and their relation to manifestations of myocardial ischaemia.


    Methods
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Patients and design
The substudy population consisted of 320 consecutive patients recruited in 19 of the 61 participating centres of the TRIM study. Details of the TRIM study protocol and the main results have previously been reported.20 Eligible for inclusion were men and post-menopausal women between 25 and 80 years of age with unstable angina, defined as new onset of ischaemic chest pain or rapid deterioration in previously stable angina during the last 4 weeks, or suspicion of a non-Q-wave myocardial infarction. This clinical diagnosis had to be supported by either changes in the resting ECG, e.g. ST-depression or T-wave inversion, or previously known coronary artery disease.

Patients were, within 24 h from the qualifying episode of chest pain, randomized to blinded treatment with unfractionated heparin or one of three different fixed doses of inogatran. Low, medium and high dose inogatran patients received intravenous bolus injections of 1.10; 2.75 and 5.50 mg respectively, followed by continuous infusion of 2.0; 5.0 and 10.0mg.h–1respectively. Heparin was administered as a 5000 U intravenous bolus injection followed by infusion with 1200U.h–1. All infusions were to be continued for 72 h. Aspirin was strongly recommended and given to 96% of the patients within the first day, but other platelet inhibitors and oral anticoagulants were notallowed.

Fibrinogen, C-reactive protein andtroponin T
Venous blood samples were obtained, preferably by direct venipuncture, into citrated tubes for analyses of fibrinogen and C-reactive protein and into heparin tubes for analysis of troponin T. Samples for analyses of fibrinogen and C-reactive protein were collected pre-treatment, during study drug infusion at 24 and 72 h and 24 h after cessation of infusion at 96 h, and finally at 30 days follow-up. For the analysis of troponin T, samples were drawn pre-treatment, at 6 and 12 h. The first 2 ml blood were disposed of and the samples were within30 min centrifuged at 2000 g for 20 min. Aliquots of 500 µl plasma in Eppendorf tubes were frozen and stored at –70°C until analysis.

Fibrinogen was analysed by rate nephelometry with a Beckman Array protein system (Beckman Instruments Inc). The assay was performed according to the recommendations of the manufacturer, except that goat antihuman fibrinogen (Atlantic Antibodies) was used. The assay was calibrated against a human plasma standard (Behring Diagnostics GmbH). C-reactive protein was analysed with the Immulite system, a chemiluminescent enzyme-labelled immunometric assay based on a ligand-labelled monoclonal antibody and separationby antiligand-coated solid phase (Immulite CRP, Diagnostic Products Corporation).23

Measurements of troponin T (ELISA Troponin(e) T) were carried out with an ES 300 analyser(Boehringer Mannheim GmbH). The discriminator value for myocardial cell injury recommended by the manufacturer was 0.1µg.l–1,24 but evaluations were also performed using 0.06µg.l–1as cut-off.

End-points
Clinical end-points were a composite of death or nonfatal myocardial (re-)infarction at 72 h (theend of infusion), 7 and 30 days. Myocardial(re-)infarction was diagnozed using standardclinical, ECG and cardiac marker criteria.20 Anindependent end-point committee evaluated all end-points.25

Long-term follow-up data were obtained from 286 of the 320 patients at a median of 29 months (range 12–50 months). This information wasobtained from hospital records and local or national registries. If data in these sources were missing the information was collected by telephone interview.

Statistics
Differences in the levels of inflammation markers were judged with non-parametric tests, between-group comparisons with Mann-Whitney or Kruskal-Wallis tests as appropriate, and within-group differences between different time-points with Wilcoxon signed rank tests. The levels of inflammatory markers and their relation to clinicaloutcome were evaluated for the total substudy population. Fisher exact test (two-sided) or chi2tests as appropriate were used to judge significance of differences in proportions.


    Results
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
There were no significant differences betweenpatients in the four treatment groups in levels of fibrinogen or C-reactive protein either pre-treatment, during the 72 h of anticoagulant treatment, or at 24 h and 30 days thereafter. There were furthermore no significant differences between heparin and the combination of the three inogatran groups, or between any of the three inogatran groups concerning the composite end-point after 7 or 30 days.20

Baseline characteristics
Taking all treatment groups together, patients with high pre-treatment fibrinogen levels, i.e. in the top tertile, were older (median 68 vs 65 years, P=0.003) and had in higher proportion a history of stable angina >4 weeks (74% vs 62%, P=0.04), previous myocardial infarction (55% vs 42%, P=0.03) and congestive heart failure (26% vs 8%, P<0.001). Hypertension and diabetes mellitus were present in 39% and 17% of the patients, respectively, without differences in relation to pre-treatment fibrinogen levels. There were no differences in baseline characteristics in relation to pre-treatment C-reactive protein levels.

Time-course of changes in fibrinogen and C-reactive protein levels
Median time from onset of chest pain to randomization was 12 h, and 20% of the 320 patients were randomized within 6 h of symptom onset. Overall there was a significant increase in fibrinogen during the first 24 h after randomization, which seemed to reach its maximum after 72–96 h (Table 1). After30 days the fibrinogen levels still remained significantly higher than pre-treatment. The increase in C-reactive protein levels was, as compared to changes in fibrinogen levels, more pronounced with a large upward dispersion during the first 24–96 h (Table 1). In contrast to fibrinogen, the levels of C-reactive were markedly decreased from day 4 to day 30, when the level tended to be lower than pre-treatment.


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Table 1 Time-course of changes in fibrinogen and C-reactive protein

 
Fibrinogen and C-reactive protein in relation to troponin T
Pre-treatment elevation of troponin T≥0.1µg.l–1was found in samples from 138 (44%) of the 317 analysed patients. These troponin-positive patients had significantly higher levels of fibrinogen and C-reactive protein pre-treatment and at 24–96 h (Fig. 1). In both troponin-positive and troponin-negative patients there was a significant further increase in levels of fibrinogen and C-reactiveprotein during the first 24–96 h (Fig. 1). Thisincrease in levels of fibrinogen and C-reactive protein in troponin-negative patients was still significant when excluding patients with clinical events, i.e. death or myocardial (re-)infarction during the study.



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Fig. 1 Distribution of (a) fibrinogen or (b) C-reactive protein in relation to pre-treatment levels of troponin T<0.1µg.l–1(white boxes) or ≥0.1µg.l–1(shaded boxes). Box-plots contain median, first and third quartiles and in the whiskers 10th and 90th percentiles. Mann-Whitney test for between-group comparisons, Wilcoxon signed rank test (within-group) compared to pre-treatment, *P<0.05, **P<0.01, ***P<0.001.

 
Similar results were found using 0.06µg.l–1as cut-off limit for pre-treatment troponin T or positive troponin T in serial samples within the first12 h.

Clinical outcome in relation to fibrinogen and C-reactive protein
High fibrinogen levels, i.e. in the pre-treatment top tertile, were related to increased risk of ischaemic events at 30 days (Table 2). However, the rate of adverse ischaemic events tended to be lower during the ongoing anticoagulant treatment in patients with high pre-treatment fibrinogen, but within the first 4 days after cessation of treatment there was a clinical reactivation with a more than doubledischaemic event rate (Fig. 2). Thus, 12 of the 100 patients with pre-treatment levels of fibrinogenin the top tertile (and without ischaemic events during treatment) died or experienced a myocardial (re-)infarction from cessation of treatment to 30-days follow-up, as compared to seven (3.4%) of the 208 patients with lower pre-treatmentfibrinogen levels, P=0.003. Furthermore, a high pre-treatment level of fibrinogen was a predictor of long-term mortality (Fig. 3).


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Table 2 Clinical outcome at 30 days in relation to pre-treatment levels of fibrinogen and C-reactive protein

 


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Fig. 2 Composite of death and myocardial (re-)infarction in relation to pre-treatment levels of fibrinogen or C-reactive protein. Pre-treatment top tertile indicated by a solid line and bottom+middle tertile by a broken line. Vertical line indicates cessation of study drug.

 


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Fig. 3 Probability of death during long-term follow-up, median 29 months; min 12 months, max 50 months; in relation to pre-treatment levels of fibrinogen or C-reactive protein, top vs bottom+middle tertile. Statistics: Log rank test.

 
Pre-treatment C-reactive protein levels were not related to the composite of death or myocardial (re-)infarction during or after anticoagulant treatment. However, high pre-treatment C-reactive protein, i.e. in the top tertile, was significantly related to increased mortality at 30 days (Table 2) and associated with a trend for increased long-term mortality (Fig. 3).


    Discussion
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 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 
Active inflammation, reflected by elevated levels of interleukins5 and acute-phase proteins, e.g.fibrinogen and C-reactive protein,6,7 in unstable coronary artery disease has previously beenreported. In the present study, the changes in the levels of fibrinogen and C-reactive protein had different time-courses. The fibrinogen level started to rise at 24 h, seemed to reach its maximum after 72–96 h and remained at 30 days higher than before treatment. The initial increase in levels of C-reactive protein occurred somewhat earlier andwas more pronounced. However, the C-reactive protein level at 30 days tended to be lower than before treatment. Neither the time-course of levels of fibrinogen nor C-reactive protein levels seemed affected by the different doses of inogatran or UF heparin treatment. Therefore, the short-termelevation of C-reactive protein seems mainlyrelated to a transient increase in inflammatory activity, with spontaneous resolution, while the continuous elevation of fibrinogen indicates the co-existence of a chronic low-grade inflammatory condition.

There are limited data concerning the inflammatory activity in patients with unstable angina in relation to signs of myocardial cell damage. Consistent with previous studies, the troponin-positive patients had significantly higher levels of fibrinogen and C-reactive protein pre-treatment and up to at least 96 h thereafter in the present study. This enhanced acute-phase reaction is probably induced by the myocardial cell damage.26–28

In a previous study18 of unstable angina patients without troponin elevation, there was no increase in the levels of C-reactive protein up to 96 h after admission, despite ischaemic episodes during 24 h continuous ECG-monitoring in the majority of the patients. In contrast, elevated levels of C-reactive protein despite normal troponin T on admission were reported in another study of unstable angina patients.7 In eight of these 20 patients the C-reactive protein level was doubled at 24–72 h after admission, and all of them had an inhospital major coronary event (death or myocardial infarction) or underwent urgent revascularization. The present study is thus the first to report a significant acute-phase response, with an early increase in fibrinogen and especially C-reactive protein, in a large number of unstable angina patients without any signs of myocardial cell damage. This acute-phase reaction indicates other sources of inflammatory activity than myocardial cell injury in the acute phase of unstable coronary artery disease.12 Recently, polymorphism in exon 2 of the C-reactive protein gene has been described, although noassociation with C-reactive protein regulation or concentration is known.29 One might speculate that differences in the acute-phase response in unstable coronary artery disease might reflect differences in the individual response to inflammatory stimuli.2,30 Interestingly, higher C-reactive protein levels have been reported in the offspring of patients with myocardial infarction.31 Thus, a low grade inflammatory activity, indicated by slight elevation of C-reactive protein and long-lasting fibrinogenelevation, might be associated with a propensity to a pronounced inflammatory response on plaqueruptures and/or thromboembolic myocardialdamage.

Several epidemiological studies have identified elevated levels of markers of inflammation, mainly C-reactive protein, as risk indicators for future cardiovascular events, both in apparently healthy men32–35 and women.36 Furthermore, both fibrinogen and C-reactive protein have been found to indicate increased short- and long-term risk for adverse clinical outcome in unstable coronaryartery disease.7,13–17

The differences in magnitude and time-courseof elevations of fibrinogen and C-reactive protein levels observed in the present study might indicate different underlying mechanisms of theirassociations to new ischaemic events in unstable coronary artery disease. A high fibrinogen level was related with a trend towards a lower rate of clinical events during ongoing anticoagulant treatment,but also marked clinical reactivation after cessation of treatment with a significantly higher rate of ischaemic events at 30 days. Fibrinogen is directly involved in the thrombotic process, both in platelet aggregation cross-linking the glycoprotein IIb/IIIa-receptors on adjacent platelets, and in the coagulation cascade where it is cleaved by thrombin to soluble fibrin which subsequently polymerises to form the fibrin network stabilising the platelet clot.11 The sustained high levels of fibrinogenmight thereby be associated with long-term risk of thrombosis and myocardial (re-)infarction.13

On the other hand, the C-reactive protein level was only related to increased mortality and not to myocardial (re-)infarction in the present as in other trials.13,16,37,38 Similar to these results, elevated levels of interleukin-6 have been related toincreased mortality, but not an increase in the combined end-point of death and myocardialinfarction, in patients with unstable coronaryartery disease.39 C-reactive protein is mainly regulated by interleukin-6, which is present in the atherosclerotic plaque and secreted by bothendothelial cells, smooth muscle cells, macrophages and T-cells.40 High levels of interleukin-6 may thereby reflect a greater atheroscleroticburden and/or increased inflammatory activity in the plaques. Thus, these plaques would be more vulnerable and prone to deeper fissuring, causing more severe thrombotic episodes.39 However, the largest increase in C-reactive protein was observed in patients with myocardial cell injury. Also the raised mortality was mainly seen in the top tertile of C-reactive protein. Therefore, much of the relation between the C-reactive protein level and mortality could be explained by an inflammatory reaction in the damaged myocardium.

In conclusion, myocardial cell injury, asdetected by elevated troponins, was associated with a higher degree of inflammation, only in part explained by an acute-phase response due to the tissue damage. The elevation of fibrinogen levels in the acute phase was sustained for at least 30 days, which might reflect a low grade inflammatorycondition in atherosclerotic lesions and a prothrombotic state, thus explaining the association between the fibrinogen level and the long-term risk for thrombosis and new ischaemic events. This risk seems diminished during treatment with thrombin inhibitors, but recurs early after cessation of treatment. The pronounced elevation of C-reactive protein levels in the acute phase was transient, which might indicate a propensity to a pronouncedinflammatory response at plaque ruptures and/or thromboembolic myocardial damage, both of which might be associated with increased mortality. The mechanisms of the inflammatory response in the acute phase of unstable coronary disease need to be further explored in order to understand their association with future cardiovascular incidents.


    Acknowledgments
 
This study was supported by AstraZeneca AB,Mölndal, Sweden and by grants from the Swedish Heart and Lung Foundation, Uppsala CountyAssociation against Heart and Lung Diseases, and the Faculty of Medicine, Uppsala University.We acknowledge Birgitta Fahlström for excellent technical assistance.


    References
 Top
 Abstract
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 Methods
 Results
 Discussion
 References
 

  1. Falk E, Shah PK, Fuster V. Coronary plaque disruption. Circulation. 1995;92:657–671[Free Full Text]
  2. Ross R. Atherosclerosis-an inflammatory disease. N Engl J Med. 1999;340:115–126[Free Full Text]
  3. Maseri A, Liuzzo G, Biasucci LM. Pathogenic mechanisms in unstable angina. Heart. 1999;82(Suppl 1):12–14
  4. van der Wal AC, Becker AE, van der Loos CM, et al. Site of intimal rupture or erosion of thrombosed coronary atherosclerotic plaques is characterized by an inflammatoryprocess irrespective of the dominant plaque morphology. Circulation. 1994;89:36–44[Abstract]
  5. Biasucci LM, Vitelli A, Liuzzo G, et al. Elevated levels of interleukin-6 in unstable angina. Circulation. 1996;94:874–877[Abstract/Free Full Text]
  6. Berk BC, Weintraub WS, Alexander RW. Elevation of C-reactive protein in ‘active’ coronary artery disease. Am J Cardiol. 1990;65:168–172[ISI][Medline]
  7. Liuzzo G, Biasucci LM, Gallimore JR, et al. The prognostic value of C-reactive protein and serum amyloid A protein in severe unstable angina. N Engl J Med. 1994;331:417–424[Abstract/Free Full Text]
  8. Jude B, Agraou B, McFadden EP, et al. Evidence for time-dependent activation of monocytes in the systemic circulation in unstable angina but not in acute myocardial infarction or in stable angina. Circulation. 1994;90:1662–1668[Abstract]
  9. Neri Serneri GG, Prisco D, Martini F, et al. Acute T-cell activation is detectable in unstable angina. Circulation. 1997;95:1806–1812[Abstract/Free Full Text]
  10. Ruggeri ZM, Dent JA, Saldivar E. Contribution of distinct adhesive interactions to platelet aggregation in flowing blood. Blood. 1999;94:172–178[Abstract/Free Full Text]
  11. Furie B, Furie BC. Molecular and cellular biology of blood coagulation. N Engl J Med. 1992;326:800–806[ISI][Medline]
  12. Lagrand WK, Visser CA, Hermens WT, et al. C-reactive protein as a cardiovascular risk factor: more than an epiphenomenon? Circulation. 1999;100:96–102[Abstract/Free Full Text]
  13. Toss H, Lindahl B, Siegbahn A, et al. Prognostic influence of increased fibrinogen and C-reactive protein levels in unstable coronary artery disease. FRISC Study Group. Fragmin during Instability in Coronary Artery Disease. Circulation. 1997;96:4204–4210[Abstract/Free Full Text]
  14. Becker RC, Cannon CP, Bovill EG, et al. Prognostic value of plasma fibrinogen concentration in patients with unstable angina and non-Q-wave myocardial infarction (TIMI IIIB Trial). Am J Cardiol. 1996;78:142–147[CrossRef][ISI][Medline]
  15. Haverkate F, Thompson SG, Pyke SD, et al. Production of C-reactive protein and risk of coronary events in stable and unstable angina. European Concerted Action on Thrombosis and Disabilities Angina Pectoris Study Group. Lancet. 1997;349:462–466[CrossRef][ISI][Medline]
  16. Heeschen C, Hamm CW, Bruemmer J, et al. Predictive value of C-reactive protein and troponin T in patients with unstable angina: a comparative analysis. CAPTURE Investigators. Chimeric c7E3 AntiPlatelet Therapy in Unstable angina REfractory to standard treatment trial. J Am Coll Cardiol. 2000;35:1535–1542[CrossRef][ISI][Medline]
  17. Lindahl B, Toss H, Siegbahn A, et al. Markers of myocardial damage and inflammation in relation to long-term mortality in unstable coronary artery disease. FRISC Study Group. Fragmin during Instability in Coronary Artery Disease. N Engl J Med. 2000;343:1139–1147[Abstract/Free Full Text]
  18. Liuzzo G, Biasucci LM, Rebuzzi AG, et al. Plasma protein acute-phase response in unstable angina is not induced by ischemic injury. Circulation. 1996;94:2373–2380[Abstract/Free Full Text]
  19. Ferreiros ER, Boissonnet CP, Pizarro R, et al. Independent prognostic value of elevated C-reactive protein in unstable angina. Circulation. 1999;100:1958–1963[Abstract/Free Full Text]
  20. The TRIM study group. A low molecular weight, selective thrombin inhibitor, inogatran, vs heparin for unstablecoronary artery disease. Eur Heart J. 1997;18:1416–1425[Abstract]
  21. Gustafsson D, Elg M, Lenfors S, et al. Effects of inogatran, a new low-molecular-weight thrombin inhibitor, in rat models of venous and arterial thrombosis, thrombolysis and bleeding time. Blood Coagul Fibrinolysis. 1996;7:69–79[Medline]
  22. Teger-Nilsson AC, Bylund R, Gustafsson D, et al. In vitro effects of inogatran, a selective low molecular weight thrombin inhibitor. Thromb Res. 1997;85:133–145[CrossRef][Medline]
  23. Babson AL, Olson DR, Palmieri T, et al. The IMMULITE assay tube: a new approach to heterogeneous ligand assay. Clin Chem. 1991;37:1521–1522[Free Full Text]
  24. Müller-Bardorff M, Hallermayer K, Schroder A, et al. Improved troponin T ELISA specific for cardiac troponin T isoform: assay development and analytical and clinical validation. Clin Chem. 1997;43:458–466[Abstract/Free Full Text]
  25. Naslund U, Grip L, Fischer-Hansen J, et al. The impact of an end-point committee in a large multicentre, randomized, placebo-controlled clinical trial: results with and without the end-point committee in a large multicentre, randomized, placebo-controlled clinical trial: results with and without the end-point committee's final decision on end-points. Eur Heart J. 1999;20:771–777[Abstract/Free Full Text]
  26. de Beer FC, Hind CR, Fox KM, et al. Measurement of serum C-reactive protein concentration in myocardial ischaemia and infarction. Br Heart J. 1982;47:239–243[Abstract]
  27. Pietila K, Harmoinen A, Poyhonen L, et al. C-reactive protein in subendocardial and transmural myocardial infarcts. Clin Chem. 1986;32:1596–1597[Medline]
  28. Hoffmeister HM, Büttcher E, Ehlers R, et al. Troponin release is associated with activation of an acute phase inflammatory reaction in unstable angina pectoris (Abstr Suppl). Eur Heart J. 2000;21:P2836 : 522
  29. Cao H, Hegele RA. Human C-reactive protein (CRP) 1059G/C polymorphism. J Hum Genet. 2000;45:100–101[CrossRef][ISI][Medline]
  30. Yoshimoto T, Nakanishi K, Hirose S, et al. High serum IL-6 level reflects susceptible status of the host to endotoxin and IL-1/tumor necrosis factor. J Immunol. 1992;148:3596–3603[Abstract/Free Full Text]
  31. Margaglione M, Cappucci G, Colaizzo D, et al. C-reactive protein in offspring is associated with the occurrence of myocardial infarction in first-degree relatives. Arterioscler Thromb Vasc Biol. 2000;20:198–203[Abstract/Free Full Text]
  32. Thompson SG, Kienast J, Pyke SD, et al. Hemostatic factors and the risk of myocardial infarction or sudden death in patients with angina pectoris. European Concerted Action on Thrombosis and Disabilities Angina Pectoris Study Group. N Engl J Med. 1995;332:635–641[Abstract/Free Full Text]
  33. Ridker PM, Cushman M, Stampfer MJ, et al. Inflammation, aspirin, and the risk of cardiovascular disease in apparently healthy men. N Engl J Med. 1997;336:973–979[Abstract/Free Full Text]
  34. Koenig W, Sund M, Frohlich M, et al. C-Reactive protein, a sensitive marker of inflammation, predicts future risk of coronary heart disease in initially healthy middle-aged men: results from the MONICA (Monitoring Trends and Determinants in Cardiovascular Disease) Augsburg Cohort Study, 1984 to 1992. Circulation. 1999;99:237–242[Abstract/Free Full Text]
  35. Danesh J, Whincup P, Walker M, et al. Low grade inflammation and coronary heart disease: prospective study and updated meta-analyses. BMJ. 2000;321:199–204[Abstract/Free Full Text]
  36. Ridker PM, Buring JE, Shih J, et al. Prospective study of C-reactive protein and the risk of future cardiovascular events among apparently healthy women. Circulation. 1998;98:731–733[Abstract/Free Full Text]
  37. Koukkunen H, Penttila K, Kemppainen A, et al. C-reactive protein, fibrinogen, interleukin-6 and tumour necrosisfactoralpha in the prognostic classification of unstableangina pectoris. Ann Med. 2001;33:37–47[ISI][Medline]
  38. James S, Armstrong P, Califf R, et al. C-reactive protein is independently related to mortality but not to myocardial infarction in unstable coronary artery syndrome. (Abstr Suppl)Eur Heart J. 2001;22:P2827 :517
  39. Lindmark E, Diderhom E, Wallentin L, et al. Relationship between interleukin-6 and mortality in patients with unstable coronary artery disease. Effects of an early invasive or non-invasive strategy. JAMA. 2001;286:2107–2113[Abstract/Free Full Text]
  40. Schieffer B, Schieffer E, Hilfiker-Kleiner D, et al. Expression of angiotensin II and interleukin 6 in human coronary atherosclerotic plaques: potential implications for inflammation and plaque instability. Circulation. 2000;101:1372–1378[Abstract/Free Full Text]