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Cardiac Biomarkers by sandip

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Cardica Biomarkers

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Cardiac Biomarkers by sandip

  1. 1. CARDIAC BIOMARKERS BY Mr.Sandip Kanazariya 1
  2. 2. BIOMARKER “A biomarker is a substance used as an indicator of a biologic state”. Morrow and de lomos three criteria for biomarkers – Accurate repeated measurements at reasonable cost – Must provide additional information – Should aid treatment 2
  3. 3. HEART FAILURE Heart failure a major and growing health problem appears to result not only from cardiac overload or injury but also from complex interplay among genetic, inflammatory and biological changes acting on cardiac myocytes, the cardiac interstitium or both. ACUTE MYOCARDIAL INFARCTION A sudden occlusion of a coronary artey by thrombus or by embolisation causes an acute myocardial infarction. 3
  4. 4. CARDIAC BIOMARKERS • Cardiac biomarkers are protein molecules released into the blood stream from damaged heart muscle • Since ECG…… inconclusive ….biomarkers !!!!!????? myocardial injury • These biomarkers have a characteristic rise and fall pattern 4
  5. 5. CHARACTERISTICS OF AN IDEAL CARDIAC MARKER • High cardiac specificity • Pharmacokinetics of cardiac biomarker • Easy diagnosis • Marker should play a designed role in the treatment and management of clinical subject 5
  6. 6. HISTORY OF CARDIAC BIOMARKERS • 1954 - SGOT (AST) • 1955 - LDH • 1960 - CPK • 1972 - CPK isoforms by Electrophoresis • 1975 - CK - MB by immunoinhibition • 1975 - Myoglobin • 1985 - CK - MB Mass immunoassay • 1989 - Troponin T • 1992 - Troponin I 6
  7. 7. CLASSIFICATION OF CARDIAC BIOMARKERS • Biomarkers of myocardial injury – markers of myocardial necrosis – markers of myocardial ischemia • Biomarkers of haemodynamic stress • Inflammatory and prognostic Biomarkers 7
  8. 8. 8
  9. 9. BIOMARKERS OF MYOCARDIAL INJURY • Markers of myocardial necrosis – Creatine kinase – MB – Myoglobin – Cardiac troponins • Markers of myocardial ischemia Ischemia Modified Albumin (IMA) Heart-type fatty acid binding protein (H-FABP) 9
  10. 10. 10
  11. 11. 11
  12. 12. Zones of Ischemia Injury and Infarction with Transmural and Subendocardial Infarction 12
  13. 13. CREATINE KINASE Creatine kinase (CK/CPK) is an enzyme expressed in a number of tissues. Function: it catalyses the conversion of creatine to phosphocreatine degrading ATP to ADP The CK enzyme consists of two subunits, B (brain type) or M (muscle type), Making three different isoenzymes: CK-MM, CK-BB and CK-MB • CK-BB occurs mainly in tissues, rarely of any significance in the bloodstream • Skeletal muscle expresses CK-MM (98%) and low levels of CK- MB (1%) • The myocardium has CK-MM at 70% and CK-MB at ~30% 13
  14. 14. CK-MB • High specificity for cardiac tissue • Begins to rise 4-6 hours after onset of infarction • Peaks at about 12 hours • Returns to baseline at 24-36 hours • Can be used to indicate early re-infarction if level normalizes and then increases again 14
  15. 15. DETECTION • CK-MB now measured via a highly sensitive monoclonal antibody assay • Immunological Sandwich technique using two Abs for different epitopes of CK –MB molecule • The first Ab is rendered immobile on a matrix (e.g. CrO2 particles) • The second Ab conjugate to an enzyme (β- galacto- sidase) • Separated bound sandwiches are reacted with their substrate (e.g. Chlorophenol β- Red Galactopyranoside) • Liberated end product chlorophenol is measured spectrophotometrically and is proportionate to CK-MB amount (not the activity) 15
  16. 16. 16
  17. 17. DETECTION • The CK-MB isoforms may also be analyzed using high- voltage electrophoresis • The ratio of MB2/MB1 is calculated • MB2 released from heart muscle and converted to MB1 • A level of MB2 > or = 1 and a ratio of MB2/MB1 > 1.5 indicates myocardial injury • A result is positive if MB2 is elevated and the ratio is more than 1.5 17
  18. 18. DRAWBACKS • False positive (for MI) CK-MB elevation can be seen in: – Significant skeletal muscle injury – The MB fraction is determined to be expressed during the process of muscle regeneration – Cardiac injury for reason other than MI • Defibrillation • Blunt chest trauma • Cocaine abuse The search for cardiac specificity continues… 18
  19. 19. MYOGLOBIN • Small-size heme protein found in all tissues mainly assists in oxygen transport • It is released from all damaged tissues • Increases often occur more rapidly than TI and CK • Released from damaged tissue within 1 hour • Normal value: 17.4-105.7 ng/ml • Timing: – Earliest Rise: 1-3 hrs – Peak 6-9 hrs – Return to normal: 12 hrs 19
  20. 20. CONDITIONS FOR MYOGLOBIN INCREASE • Acute myocardial infarction • Skeletal muscle damage, muscular dystrophy, inflammatory myopathies • Renal failure, severe uremia • Shock and trauma 20
  21. 21. CLINICAL USEFULNESS OF MYOGLOBIN • Rapid monitor of success of thrombolytic therapy • Negative predictor of MI DRAWBACKS • Due to poor specificity, myoglobin levels do not always predict myocardial injury • Not utilized often for AMI/cardiac damage assessment because of its very rapid metabolism 21
  22. 22. CARDIAC TROPONINS • Troponin is a complex of three regulatory proteins that is integral to non-smooth muscle contraction in skeletal as well as cardiac muscle • Troponin is attached to the tropomyosin sitting in the groove between actin filaments in muscle tissue • Troponin has three subunits, TnC, TnT, and TnI – Troponin-C has calcium binding ability and has no diagnostic value – Troponin-T binds the troponin tropomyosin complex, – Troponin-I is an inhibitory protein 22
  23. 23. 23
  24. 24. Cardiac Troponin Release after MI 24
  25. 25. TROPONIN I 1. Cardiac Troponin I (cTnl) is a cardiac muscle protein with a molecular weight of 24 kilo-Daltons. 2. The cTnl has a additional amino acid residues on its N- terminal that are not exist on the skeletal form. 3. The half life = 2~4 hours. 4. Serum increase = 2-8 hours 25
  26. 26. TROPONIN T 1. Cardiac Troponin T (cTnT) is present in fetal skeletal muscle. 2. In healthy adult skeletal muscle cTnT is absent. 3. The gene of cTnT may be re-expressed in skeletal muscle disease. (Clin Chem. 1999;45:2129-2135) 4. Biological half life and early serum increases of cTnT are similar to that of cTnI. 26
  27. 27. TROPONIN LEVELS • Less than 5% in cytosol • Troponin levels begin to rise 2-3 hours after onset of myocardial injury • Elevations in Troponin-I and Troponin-T can persist for up to 10 days after MI • Remember, CK-MB returns to baseline by 48 hours • Thus far, studies have failed to find a source of Troponin- I outside the heart, but have found some Troponin-T in skeletal muscle 27
  28. 28. COMPARISON NEJM 2002;Vol.346,No.26:2079-82 28
  29. 29. COMPARISON 29
  30. 30. Conditions commonly associated with cardiac troponin elevations • Arrhythmias • Congestive heart failure • Coronary artery disease • Coronary vasospasm • Critically ill patient • Hypertension • Myocarditis • Pericarditis • Pulmonary embolism • Pulmonary hypertension, severe • Renal failure • Sepsis/septic shock • Sepsis-related myocardial dysfunction • Systemic inflammatory diseases • Trauma 30
  31. 31. Increased Troponins • Troponin T and I are not detected in healthy individuals • Significant increase in Troponins reflects myocardial necrosis • ACC/ESC has defined increase in Troponins as a measurement above 99th percentile value of reference group • To reduce false-positive outcomes, CV of 10% at decision limit is recommended 31
  32. 32. TROPONIN ASSAYS • TropT (Roche Diagnostics, Germany) • Trop I (Siemens Healthcare Diagnostics) • Troponin T – 99th percentile limits - 0.01 ng/mL – assay ranges - 0.01-25 ng/mL • (Troponin I) – 99th percentile limits -0.04 ng/mL – assay range -0.04-40 ng/mL • Reference limits based on the 99th percentile for a healthy population are 0.01 ng/mL (Troponin T) and 0.04 ng/mL (Troponin I) 32
  33. 33. DIAGNOSIS BASED ON SENSITIVE TROPONIN I ASSAY They used the concentration of 0.04 ng per mL as the upper reference limit and established the diagnosis of myocardial infarction if one value of more than 0.04 ng per mL was documented, combined with a rise or fall in the value of 30% or more within 6 hours after admission. Patients with troponin rises benefit more from Glycoprotein IIb IIIa inhibitors such as, • Abciximab • Eptifibatin • Clopidogrel 33
  34. 34. IN VETERINARY USE • Most commonly used in dogs and cats Clinical conditions • Congestive heart failure • Percardial disease • Doxorubicin toxicity • Gastric dilatation and volvulus etc,. 34
  35. 35. Fonflora et al study 120 animals were examined in emergency with cardiac troponin assays, • First group= ctni less than .15ng/ml • Second group= ctni .15-1 ng/ml • Third group= ctni more than 1 ng/ml Prognosis grave in second and third group 35
  36. 36. 36
  37. 37. BIOMARKERS OF MYOCARDIAL ISCHEMIA 37
  38. 38. Ischemia Modified Albumin (IMA) • A novel marker of ischemia, is produced when circulating serum albumin contacts ischemic heart tissues • IMA can be measured by the albumin cobalt binding (ACB) assay that is based on IMA's inability to bind to cobalt • Mechanism- due to structural change in the amino terminal end of albumin • IMA levels rise within 6 hours • remain elevated for 12 hours 38
  39. 39. Drawbacks IMA levels raised in non- cardiac ischemia Modification to n- terminal end may also be induced by extracellular hypoxia, acidosis etc, Conclusion FDA in 2010 has approved a multimarker approach for using the combination of ECG, the cTnI, and the IMA levels achieving a sensitivity of 95% for ACS 39
  40. 40. Heart-type fatty acid binding protein (H-FABP) • H-FABP is a very stable abundant [138] low molecularweight protein (14–15 kDa) in the cytoplasm of myocardial cells • Appearing as early as 90 min after symptom onset and peaking within 6 h • Parameters of kinetic release make it an ideal candidate both for early assessment or exclusion of AMI and for the measurement of a recurrent infarction 40
  41. 41. • A study by Puls et al – the negative predictive value (NPV) of H-FABP was an impressive 100% – its Positive predictive value was 41% which was greater than that of both cTnT (29%) and NT- proBNP (19%). • The myoglobin/heart FABP ratio has been used to differentiate between heart muscle and skeletal muscle injury • Cardiodetect 41
  42. 42. BIOMARKERS OF HAEMODYNAMIC STRESS 42
  43. 43. NATRIURETIC PEPTIDES 43
  44. 44. NATRIURETIC PEPTIDES • The natriuretic peptides (NP) are a group of structurally similar but genetically distinct peptides. • NPs are identified as regulatory diuretic-natriuretic substances responsible for salt and water homeostasis • Lowers blood pressure. 44
  45. 45. • The NP family includes ANP : -atrial natriuretic peptide (28 a.a.) N-terminal proANP (98 a.a.) BNP : brain natriuretic peptide (32 a.a.) N-terminal proBNP (76 a.a.) CNP : C-type natriuretic peptide (22 and 53 a.a.) 45
  46. 46. Fig. Schematic representation of the ANP and BNP precursors with sequence numbering defining low-molecular-mass forms, N-terminal forms and high- molecular-mass precursors 46
  47. 47. NATRIURETIC PEPTIDES • ANP is released primarily in response to atrial wall stretching and intravascular volume expansion. • BNP is mainly secreted by the ventricles • CNP is found predominantly in the brain and also synthesized by vascular endothelial cells 47
  48. 48. BRAIN NATRIURETIC PEPTIDE (BNP) • originally isolated from porcine brain • Subsequently also isolated from human heart • Circulating levels of BNP are raised in patients with cardiovascular or renal disease • More important than ANP in heart failure • Greatest proportion of circulating BNP is thought to come from the ventricles (left) 48
  49. 49. • Synthesis Synthesis in myocytes 49
  50. 50. Natriuretic peptide receptor Three receptors for natriuretic peptides : Natriuretic peptide receptor -A Natriuretic peptide receptor -B Natriuretic peptide receptor -C NPR-A and NPR-B • NPR-A and NPR-B are particulate guanylyl cyclases that catalyses the conversion of GTP to c-GMP • NPR-C They lack the guanyl cyclase domain and may influence the target cell function through inhibitory guanine nucleotide (Gi) protein, and they likely also act as clearance receptors for circulating peptides. 50
  51. 51. RECEPTORS AND METABOLISM NPR-A and NPR-B • NPR- A is the most abundant type in large blood vessels • NPR-B predominate in the brain • Both receptors are present in the adrenal glands and the kidney • Affinity for NPR-A : ANP > BNP > CNP for NPR-B : CNP > BNP > ANP 51
  52. 52. Action of Atrial Natriuretic Peptide at Target Cells 52
  53. 53. FUNCTIONS • ANP and BNP concentrations increase in response to volume expansion and pressure overload of the heart • ANP and BNP have been shown to be physiological antagonists of the effects of (1) angiotensin II on vascular tone (2) aldosterone secretion (3) renal-tubule sodium reabsorption (4) vascular-cell growth 53
  54. 54. Natriuretic Peptides 54
  55. 55. Figure . Physiology of the natriuretic-peptide family 55
  56. 56. • Clearance factors for natriuretic peptides NPR-C and neutral endopeptidase Endopeptidase • Neutral endopeptidase inactivates all three natriuretic peptides • Present within renal tubular cells and vascular cells 56
  57. 57. Conditions or factors commonly associated with B-type natriuretic peptide or N-terminal-pro-B-type natriuretic peptide elevations • Age • Arrhythmias • Cardiomyopathy: hypertrophic, ischemic, or dilated • Congestive heart failure • Coronary artery disease • Gender • Hypertension • Left ventricular diastolic dysfunction • Pulmonary embolism • Renal failure • Right heart failure • Right ventricular overloading: fluid, or pressure overloading • Sepsis or septic shock • Sepsis-related myocardial dysfunction 57
  58. 58. Breathing Not Properly (BNP) study • Prospective study of 1586 patients presenting to the emergency department with acute dyspnea Outcomes of the study • The predictive value of BNP much superior to previous standards including radiographic, clinical exam, or Framingham Criteria • Bnp cut point was fixed at 100pg/ml and it showed 90% sensitivity and 80% specificity for diagnosing heart failure Veterinary field • Chronic left ventricular systolic and diastolic dysfunction • Cardiac vs non- cardiac dyspnoea • Recent development of ELISA kits for canine and feline NTproBNPby Guildhay Ltd (www. guildhay. Co.uk) 58
  59. 59. Therapeutic potential ANP and BNP infusion • Decrease renin and aldosterone concentration • Increase urinary sodium and water excretion Neutralendopeptidase inhibitor • Nesiritide is a new drug that is a synthetic BNP that vasodilates vessels and serves as a potent diuretic agent 59
  60. 60. BNP for Rx of decompensated heart failure Nesiritide (h-BNP) 32 amino acid sequence Recombinant technology using E-coli D R I M K R G S S S S G L G F C C S S G SGQVM K V L R R H KPS NOTE: hBNP affects assay for BNP, but can still use proBNP or one of the proANP assays 60
  61. 61. BIOMARKERS OF INFLAMMATION PROGNOSTIC MARKERS AND MARKERS OF RISK STRATIFICATION 61
  62. 62. •C-reactive protein •Myeloperoxidase •Homocysteine 62
  63. 63. 63
  64. 64. C-REACTIVE PROTEIN • CRP is an acute-phase protein produced by the liver • Pentameric structure consisting of five 23- kDa identical subunits • Plasma levels can increase rapidly to 10000x levels • High-sensitivity CRP (hs-CRP) assays 64
  65. 65. 65
  66. 66. • CRP previously known to be a marker of high risk in cardiovascular disease • More recent data may implicate CRP as an actual mediator of atherogenesis Mechanism of CRP-mediated atherogenesis: • Once ligand-bound, CRP can: – Activate the classical compliment pathway – Stimulate phagocytosis – Bind to immunoglobulin receptors – Endothelial dysfunction via ↑ NO synthesis – ↑LDL deposition in plaque by CRP-stimulated macrophages 66
  67. 67. 67
  68. 68. 68
  69. 69. Clinical Uses – Screening for cardiovascular risk in otherwise “healthy” individuals – Predictive value of CRP levels for disease severity in pre-existing Coronary artery disease Elevated levels predictive of • Long-term risk of first MI • Ischemic stroke 69
  70. 70. Limitations of CRP • Low specificity • No evidence that lowering CRP levels decreases CV risk Industry and FDA staff guidelines 2005 had given clinical cut off value as less than 1 mg/l as safe levels with hs-CRP tests CRP Risk for CVD Less than 1.0 mg/L Low 1.0-2.9 mg/L Intermediate Greater than 3.0 mg/L High 70
  71. 71. MYELOPEROXIDASE • MPO is an enzyme that aids white blood cells in destroying bacteria and viral particles • MPO catalyzes the conversion of hydrogen peroxide and chloride ions (Cl-) into hypochlorous acid • MPO is released in response to infection and inflammation • EPIC Norfolk Study Sugiyama Am J Pathology 2001 71
  72. 72. • MPO leads to oxidized LDL cholesterol – Oxidized LDL is phagocytosed by macrophages producing foam cells • MPO leads to the consumption of nitric oxide – Vasoconstriction and endothelial dysfunction • MPO can cause endothelial denuding and superficial platelet aggregation • MPO indicates activated immune cells – Activated immune cells and inflammation lead to unstable plaque • Inflammatory plaque is inherently less stable – Thin fibrous cap/fissured/denuded 72
  73. 73. 73
  74. 74. • In august 2005, FDA approved the first MPO assay, Cardio MPO tm developed by Prognostix,inc. • The test is a sandwich enzyme immuno assay • Normal plasma MPO levels are 51- 633pmol/ml 74
  75. 75. Progression of Biomarkers in ACS ACS, acute coronary syndrome; UA, unstable angina; NSTEMI, non–ST-segment elevation myocardial infarction; STEMI, ST-segment elevation myocardial infarction Adapted from: Apple Clinical Chemistry March 2005 STEMIUA/NSTEMISTABLE CAD PLAQUE RUPTURE MPO CRP IL-6 MPO ICAM sCD40L PAPP-A MPO D-dimer IMA FABP TnI TnT Myoglobin CKMB Inflammation has been linked to the development of vulnerable plaque and to plaque rupture
  76. 76. HOMOCYSTEINE • Intermediary amino acid formed by the conversion of methionine to cysteine • Moderate hyperhomocysteinemia occurs in 5-7% of the population • Recognized as an independent risk factor for the development of atherosclerotic vascular disease and venous thrombosis • Can result from genetic defects, drugs, vitamin deficiencies 76
  77. 77. • Homocysteine implicated directly in vascular injury including: – Intimal thickening – Disruption of elastic lamina – Smooth muscle hypertrophy – Platelet aggregation • Vascular injury induced by leukocyte recruitment, foam cell formation, and inhibition of NO synthesis • Normal levels less than 6micro mol/l 77
  78. 78. • Elevated levels appear to be an independent risk factor, though less important than the classic CV risk factors • Treatment includes supplementation with folate, B6 and B12 78
  79. 79. Stefan Blankenberg, MD; Renate Schnabel, MD; Edith Lubos, MD, et al., Myeloperoxidase Early Indicator of Acute Coronary Syndrome and Predictor of Future Cardiovascular Events 2005 79
  80. 80. 80
  81. 81. BIOMARKERS OF INTEREST, ALTHOUGH THEY ARE NOT CURRENTLY USED ROUTINELY 1. Serum Amyloid Protein A 2. sCD40 Ligand 3. Cytokines 4. Lipoprotein-Associated Phospholipase A2 5. Pregnancy-Associated Plasma Protein A 6. Oxidized LDL 7. Placental Growth Factor 8. Matrix Metalloproteinases 9. Monocyte Chemotactic Protein 10. Tissue Plasminogen Activator Antigen (t-PA) and Plasminogen Activator Inhibitor 1 (PAI-1) 11. Secreted Platelet Granular Substances 12. Isoprostanes 13. Urinary Thromboxane 14. Adhesion Molecules 81
  82. 82. Serum Amyloid Protein A • Serum amyloid protein A, an acute-phase protein and an apolipoprotein, has been used with hsCRP in cross-sectional studies. • It can be synergistic with hsCRP326 but is much less commonly used. • At present, no standardized assays, reference interval studies, nor consistent assay validations are available. 82
  83. 83. sCD40 Ligand • CD40 ligand is a transmembrane protein related to TNF. • It has multiple prothrombotic and proatherogenic effects. • What is usually measured is the soluble form of the receptor, sCD40 ligand, which has been shown to be a predictor of events after acute presentation. • At present, standardized assays, reference interval studies, nor consistent assay validations are not available. 83
  84. 84. Cytokines • A variety of stimulatory and inhibitory interleukins (TNF, IL-1, IL-6, IL-8, IL-12, IL-18) are thought to help mediate the elaboration of CRP and the development of atherosclerosis and acute events.121 These cytokines may stimulate or inhibit leukocytes, often through T cell–mediated processes and effects on monocytes, which are indigenous to atherogenesis. • In some studies, IL-6 is more prognostic than hsCRP. • These cytokines often have inhibitors and/or binding proteins that modulate their effects. At present, standardized assays, reference intervals studies, and consistent assay validations are not available. 84
  85. 85. Lipoprotein-Associated Phospholipase A2 • Phospholipase A2 (Lp-PLA2) is a phospholipase associated with LDL that is thought to be an inflammatory marker. • It was previously known as platelet-activating factor (PAF) acetyl hydrolase. • It is synthesized by monocytes and lymphocytes and is thought to cleave oxidized lipids to produce lipid fragments that are more atherogenic and that increase endothelial adhesion. • An FDA-approved assay for this analyte includes obligatory reference intervals. • It has been shown to be predictive of events in a primary prevention cohort, even when hsCRP is present in the model, suggesting that it measures something different from what is measured by the acute-phase reactants associated with hsCRP. 85
  86. 86. Pregnancy-Associated Plasma Protein A • Pregnancy-associated plasma protein A (PAPP-A) is a metalloproteinase that is thought to be expressed in plaques that may be prone to rupture. • The literature in this regard is mixed at present concerning its use. • At present, standardize assays, reference interval studies, and consistent assay validations are not available. • Recent data suggest that heparin administration in MI patients is associated with increased PAPP-A concentrations; this may limit its prognostic role. 86
  87. 87. Oxidized LDL • Oxidized LDL has been attributed a key role in the development of atherosclerosis. • Several methods have been used to measure it, but they yield potentially different data. • Some have correlated malondialdehyde LDL with the development of atherosclerosis and short- term events. • Direct identification with antibodies suggests that oxidized LDL may be released from vessels and may colocalize with lipoprotein a [Lp(a)] after acute events. 87
  88. 88. Placental Growth Factor • Placental growth factor is an angiogenic factor related to vascular endothelial growth factor (VEGF), which stimulates smooth muscle cells and macrophages. • It also increases TNF and MCP-1. A novel assay for this analyte is thought to provide additional prognostic information on patients who present with ACS. • At present, standardized assays, reference interval studies, and consistent assay validations are not available. 88
  89. 89. Matrix Metalloproteinases • Matrix metalloproteinases (MMPs) can degrade the collagen matrix in coronary artery or myocardium. • They are integral to remodeling of the coronary artery and/or the heart after acute events. • Elaboration of MMP-9, a gelatinase, is thought to be important in plaque destabilization; thus some have tried to measure it as a prognostic index. • Other MMPs participate in the elaboration of extracellular matrix in the heart. • Many MMPs also have inhibitors [tissue inhibitors of metalloproteinase (TIMPs)] that modulate their effects. • At present, standardized assays, reference intervals studies, and • consistent assay validations are not available. 89
  90. 90. Monocyte Chemotactic Protein • Monocyte chemotactic protein (MCP-1) is a chemokine that is thought to be responsible for the recruitment of monocytes into atherosclerotic plaque. • It has been reported to be elevated in patients with ACS and to have long-term predictive value. • However, at present, standardized assays, reference interval studies, and consistent assay validations are not available 90
  91. 91. Tissue Plasminogen Activator Antigen (t-PA) and Plasminogen Activator Inhibitor 1 (PAI-1) • t-PA is the body’s physiologic fibrinolytic activator. • PAI-1, its endogenous inhibitor, binds to t-PA. • Inhibition of fibrinolysis has been suggested to be a reason for recurrent infarction; the fact that maximal inhibition usually occurs in the early morning hours provides a potential explanation for the circadian variability of AMI. • It may also be the reason why persons with diabetes have such unstable disease; the growth factor properties of insulin stimulate increases in PAI-1. • An accurate assessment of this system includes both t- PA and PAI-1, along with some assessment of bound versus free levels. 91
  92. 92. Secreted Platelet Granular Substances • Both platelet factor 4 (PF4) and beta thromboglobulin (BTG) are secreted when platelets aggregate. • PF4 has a short half-life and is released by heparin. • BTG is not released by heparin and has a longer half- life. • Both markers have been used to assess platelet aggregation. • BTG is by far the more reliable. • At present, standardized assays, reference interval studies, and consistent assay validations are not available. 92
  93. 93. Isoprostanes • Isoprostanes are the end breakdown products of lipid peroxidation, and urinary levels have been used to assess the level of oxidative stress. • It is thought that oxidation of LDL is essential for the development of atherosclerosis, and that HDL and other antioxidants work by antagonizing this oxidative stress. • Urinary isoprostanes give some assessment of this critical process. • The most commonly measured are F2-isoprostanes, but a large number of others are available for measurement. • It does appear that they will eventually be helpful in assessing oxidative stress. 93
  94. 94. Urinary Thromboxane • Urinary thromboxane is the end metabolite of thromboxane A2, which is a measure of platelet aggregation. • Urinary levels are elevated in patients with unstable coronary disease, in keeping with the known participation of platelets in the pathogenesis of CAD. This level is difficult to ascertain, and collecting urine in the acute situation is at times problematic. 94
  95. 95. Adhesion Molecules • Adhesion molecules are a wide variety of molecules that can potentially be measured as a way of assessing the adherence of leukocytes and/or platelets or other adhesive proteins to the endothelial matrix. Some are receptors. Examples • include PECAM-1 (platelet-endothelial adhesion molecule 1), P-selectin, e-selectin, and VCAM-1 (vascular cell adhesion molecule 1). • At times, the receptor itself is measured, but often it is a soluble portion that circulates that is measured. • At present, standardized assays, reference interval studies, and consistent assay validations are not available 95
  96. 96. Choline • Choline is released after stimulation by phospholipase D and has been touted as a test of prognosis in patients with chest discomfort. • At present, standardized assays, reference interval studies, and consistent assay validations are not available. 96
  97. 97. Unbound Free Fatty Acid • Unbound free fatty acid (uFFA)39 has also been touted as a marker of ischemia. • Most fatty acid is bound, and ischemia is thought to increase the small unbound fraction. • Initial studies have reported mixed results. • At present, standardized assays, reference interval studies, and consistent assay validations are not available. 97
  98. 98. Nourin • Nourin I is a small protein released rapidly by “stressed myocytes.” • It induces changes in a variety of inflammatory cytokines and attracts neutrophils. • Preliminary studies have been done to attempt to validate its use. • At present, standardized assays, reference interval studies, and consistent assay validations are not available. 98
  99. 99. Copeptin • Copeptin, a 30 amino acid glycoprotein constituting the C-terminal portion of arginine vasopressin, has been shown to be a prognostic biomarker in hemorrhagic and septic sepsis. • More recently, data have shown that measurement of copeptin serves as a rapid and early rule-out biomarker for AMI at presentation in patients with symptoms suggestive of ACS with a normal cTn value. • An assay measuring copeptin (CT-proAVP) has been described using the Brahms Kryptor Immunology Analyzer, Diamond Diagnostics Holliston, MA. • Additional clinical and analytical validation studies will be necessary, especially head-to-head comparisons of copeptin versus the new hs-cTn assays. 99
  100. 100. References • Changes in brain natriuretic peptide and norepinephrine over time and mortality and morbidity in the Valsartan Heart FailureTrial (Val-HeFT). Circulation 2003;107: 1278-83. • Kameda K, Matsunaga T, Abe N, et al. Correlation of oxidative stress with activity of matrix metalloproteinase in patients with coronary artery disease. Eur Heart J 2003;24:2180-5. • Berry CE, Hare JM. Xanthine oxidoreductase and cardiovascular disease: molecular mechanisms and pathophysiological implications. J Physiol 2004;555: 589-606. • Kittleson MM, St. John ME, Bead V, et al. Increased levels of uric acid predict haemodynamic compromise in patients with heart failure independently of B-type natriuretic peptide levels. Heart 2007;93: 365-7. • Anker SD, Doehner W, Rauchhaus M, et al. Uric acid and survival in chronic heart failure: validation and application in metabolic function, and hemodynamic staging. Circulation 2003;107:1991-7. • Pfeffer MA, Braunwald E. Ventricular remodeling following myocardial infarction: experimental observations and clinical implications. Circulation 1990;81:1161- 72. 100
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  106. 106. THANK U 106

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