An update in Cardiac Biomarkers

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1 An update in Cardiac Biomarkers By / Abdelrafi Rigbah Hago MSc, clinical chemistry Karary university Eglal Osman Hussein MSc, clinical chemistry khartoum teaching hospital

2 Objectives by the end of this workshop the participant will be able to : 1- define the term cardiac markers 2- deffirentiate between the different type of cardiac biomarkers 3- clinical use of cardiac biomarkers 4- assays and methods of biomarkers

3 Definition of cardiac markers Defined as biological analytes that are detectable in the blood stream at elevated level during the continuum of CVD or in the immediate aftermath of myocardial damage.

4 Introduction Cardiac markers are biomarkers measured to evaluate heart function. They are often discussed in the context of myocardial infarction, but other conditions can lead to anelevation in cardiac marker level. Most of the early markers identified were enzymes, and as a result, the term "cardiac enzymes" is sometimes used. However, not all of the markers currently used are enzymes. For example, in formal usage, troponin would not be listed as a cardiac enzyme

5 ACUTE CORONARY SYNDROME (ACS) Ischemic heart diseases (acute coronary syndrome) includes: 1-Angina 2-Unstable angina 3-Myocardial infarction: most serious form of ischemia that leads to injury or even death of myocardium. The most common cause of myocardial ischemia is atherosclerosis. Risk factors for Coronary Artery Disease: 1-Age 2-Gender 3-Family history 4-Hyperlipidemia 5-Smoking 6- HTN,7- DM, 8-Obesity

6 The criteria for the diagnosis of myocardial infarction have been redefined recently, as reported in a consensus document of the (ESC) and (ACC), require at least 2of the3 following characteristics: 1- typical symptoms. 2- characteristic rise-and-fall pattern of a cardiac marker (eg, MB isoenzymes of creatine kinase) or, preferably, serum troponins (T or I); or 3- atypical electrocardiogram (ECG) pattern involving the development of Q wave

7 Acute Myocardial Infarction A rapid development of myocardial necrosis caused by prolonged ischemia (a critical imbalance between the oxygen supply and demand of the myocardium) resulting in an irreversible myocardial injury.

8 Biochemical Changes ischemia to myocardial muscles (with low O 2 supply) anaerobic glycolysis increased accumulation of Lactate decrease in ph activate lysosomal enzymes disintegration of myocardial proteins cell death & necrosis clinical manifestations (chest pain) BIOCHEMICAL MARKERS release of intracellular contents to blood ECG changes

9 Blood testing for biomarkers of myocardial injury plays an increasingly important role for the evaluation diagnosis, and triage of patients with chest pain. What were the historical cardiac biomarkers? 1950s the use of cardiac markers in the diagnosis of acute myocardial infarction began early studies focused on use of SGOT(now known as AST). the use of AST was questioned as it was not specific to cardiac injury.

10 1958 Focus then began to change to using LDH as a marker of cardiac injury. useful aid in the diagnosis of myocardial necrosis. The reliability of the test and the time element of the appearance and disappearance of the enzyme in the blood give it advantages over transminase determinations." 1960s Serum alpha hydroxybutyrate dehydrogenase was also studied. The late 1960s saw a shift to the use of serum creatinine kinase activity. CK became the preferred method due to its advantages of earlier increases, as well as higher sensitivity and specificity.

11 . 1970s-early 1980s saw a shift in research towards diagnostic assays for myofibrillar proteins. Myosin light chains, myoglobin, and troponins began being studied 1990s the cardiac biomarkers field emerged into what may be termed the 'era of cardiac troponin'. Currently cardiac troponin (ctn) is the preferred marker for diagnosis and management of suspected MI patients And so troponin has replaced CKMB as the gold standard in diagnosis of myocardial infarction

13 The Ideal Cardiac Biomarker

14 The Ideal Cardiac Biomarker Specific: no false positive (present in the myocardium absent in nonmyocardial tissues) Sensitive: no false negative (produced at high concentrations that can be measurable) Prognostic: relation between plasma level & extent of damage Persists longer: can diagnose delayed admission Reproducible Quick Acceptable (by patient and clinician)

15 The Ideal Cardiac Biomarker The ideal biomarker should be highly specific for cardiac tissues and absent from nonmyocaridal tissue Need to be easily accessible to achieve high diagnostic sensitivity Hence smaller soluble molecules with faster release kinetics and rapid clearance from injured tissue are regarded as the most suitable biomarkers for early diagnosis. However, in the case of late diagnosis, a highly stable biomarker with long half life is essential. Consequently, peak level should be reached reletively quickly and persist in circulation for few hours(ctn I&T)

16 Rapid clearance of biomarker from plasma is a crucial feature of biomarker of recurrent injury it should be also have the ability to differentiate between reversible (ischemia) and irreversible (necrosis) damage.

17 NECROSIS BIOMARKERS OF THE PAST 1-Lacdehydrogenase (LD) 2-Myosin Light Chains 3-Aspartate aminotransferase (AST)

18 Lacdehydrogenase(LD) Lactate dehydrogenase catalyses the conversion of pyruvate to lactate. LDH-1 isozyme is normally found in the heart muscle and LDH-2 is found predominately in blood serum. A high LDH-1 level to LDH-2 suggest MI. LDH levels are also high in tissue breakdown or hemolysis.

19 myocytes,sktl musc, liver, kidney, platlts & RBCs 5 major LD isoenzymes, LD1 LD5 LD1 & LD2 MI (LD1 > LD2) LD4 & LD5 hepatic or Skletal muscle injury LD2, LD3 & LD4 platelets/lymphatic (Total activity)ld h, peak-3 6 days & Normal in 8 14 days LD1 > LD2 pattern h, peak-2 to 3days & Normal in 7-10 days.

20 Normal vs. MI Normal LD1:LD2 = MI LD1:LD2 > 1

21 Conditions causing flipped LD1/LD2 without AMI Hemolysis Megoblastic & Pernicious Anemia Renal Cortex Infarction Testicular Germ Cell Tumors Small Cell Lung Carcinoma Adenocarcinoma of the Ovary Acute Coronary Insufficiency (Unstable Angina) Exercise Induced Myocardial Ischemia Polymyositis Muscular Dystrophies Well Trained Athletes Rhabdomyolysis

22 Myosin Light Chains cardiac isoform of MLC is muscle also produced by slow-twitch skeletal

23 Myocin light chain are also involved with muscle contraction, They were first thought to be unique Myocardial protein, but recent research has Determined that MLC are not More specific for cardiac injury than CK-MB determination And Troponin. There for remains of limited clinical signifcance as routine cardiac Marker.

24 Aspartate aminotransferase (AST,SGOT) This was the first used. [4] It is not specific for heart damage, and it is also one of the liver function tests. sklt muscle, liver, RBCs & myocardium T½(mitochondrial)- 10 d, (cytoplasmic)- 10 h. Isoenzymes not fractionated for clinical use 6 8 h,peak h, N- 4 to 5 d

25 NECROSIS BIOMARKERS OF THE PRESENT 1- CK 2- CK-MB Isoenzyme 3- ctnt and ctni 4- Myoglobin

26 CK: Total, Isoenzymes 3 major isoenzymes- CK- MM, MB & BB total CK activity sk musc (2500 U/g); hrt (473 U/g); brain (55 U/g). small intest,tongue,diaphragm,uterus &prostate tissue-to-plasma ratio sk muscle & myocard total CK -not recomm for routine MI.

27 CK-MB Isoenzyme The CK-MB isoform of creatine kinase is expressed in heart muscle. It resides in the cytosol and facilitates movement of high energy phosphates into and out of mitochondria. Since it has a short duration, it cannot be used for late diagnosis of acute MI but can be used to suggest infarct extension if levels rise again(ability to detect reinfarction. This is usually back to normal within 2 3 days Disadvantage : low specificity in skletal muscle injury

28 Myoglobin Myoglobin is used less than the other markers. Myoglobin is the primary oxygen-carrying pigment of muscle tissue. It is high when muscle tissue is damaged but it lacks specificity in presence of skletal muscle injury and renal insufficiency. It has the advantage of responding very rapidly, rising and falling earlier than CK-MB or troponine. Early detection of MI, It also has been used in assessing reperfusion after thrombolysis. duration of elevation: 2-24hrs.

29 TROPONINS THE GOLD STANDARD

30 CARDIAC TROPONINS It consists of 3 subunits troponin C, I, and T. The complex regulates the contraction of striated muscle. 1. TnC binds to calcium ions. 2. TnI binds to actin and inhibits actin-myosin interaction. 3. TnT binds to tropomyosin, attaching to thin filament.

31 Structure Associated with tropomyosin, which forms a continuous chain along each actin thin filament A complex of the three subunits: TN-T: tropomyosin binding subunit TN-I: myosin ATPase inhibiting subunit TN-C: calcium binding subunit

32 THE TROPONIN REGULATORY COMPLEX

33 Troponin is released during MI from the cytosolic pool of the myocytes. Its subsequent release is prolonged with degradation of actin and myosin filaments. Isoforms of the protein, T and I, are specific to myocardium. Differential diagnosis of troponin elevation includes acute infarction, severe pulmonary embolism causing acute right heart overload, heart failure, myocarditis.

34 Troponins can also calculate infarct size but the peak must be measured in the 3rd day. After myocyte injury, troponin is released in 2 4 hours and persists for up to 7 days. The most sensitive and specific test for myocardial damage. Because it has increased specificity compared with CK-MB, troponin is a superior marker for myocardial injury.

35 Cardiac troponin T Advantage : Tool for risk stratification, detection of MI up to 2 weeks Highly specific for cardiac tissue (gold standard Disadvantage not an early marker of myocardial necrosis limited ability to detect re-infarction Duration of elevation (10-14 days)

36 Cardiac proponin I Adrantage, tool for risk stratification, detection of MI up to detection of MI up to 7 days, highly specific for eaidiac tissue Disadrantage : Non an early marker of M yocardial necrosis No analytical refrance standard Limited ability to detect re-infarction Duration of elevation 4-7 days

37 Serial Sampling When initial results are negative Serial sampling at presentation, 6 9 h later, and after 12 h is recommended if the earlier results are negative and clinical suspicion remains high

39 SPECIFICITY OF CARDIAC MARKERS % 92% 90 87% % TROPONIN-I CK-MB TOTAL CK MYOGLOBIN

40 Markers of heart failure 1-Atrial natiuretic peptide (ANP) 2-type (brain) peptide 3-N-terminal pro-b-typre natriuretic peptide (N-T-pro-BNP)

41 BNP : 32 AAs plypeptide functions as a cardiac hormone secreted from the cardiac venticles against venticular overloted and pressure volume expansion. BNP ; PG-ml NT-PRO-BNP : Pg-ml The use of plasma BNP testing to confirm the diagnosis of HF in patient presenting with signs and symptoms that are either ambiguous or confounding certain disease states (COPD)

42 Natriuretic Peptides Present in two forms, atrial (ANP) and brain (BNP) Both ANP and BNP have diuretic, natriuretic and hypotensive effects Both inhibit the renin-angiotensin system and renal sympathetic activity BNP is released from the cardiac ventricles in response to volume expansion and wall stress

44 BNP Assay Approved by the FDA for diagnosis of cardiac causes of dysnpea. Currently measured via a rapid, bedside immunofluorescence assay taking 10 minutes. Especially useful in ruling out heart failure as a cause of dyspnea given its excellent negative predictive value.

45 BNP Came to market in 2000 based on data from many studies, primarily the Breathing Not Properly (BNP) study Prospective study of 1586 patients presenting to the ER with acute dyspnea The predictive value of BNP much superior to previous standards including radiographic, clinical exam, or Framingham Criteria

46 . Biomarkers of inflammation and prognosis : 1- C- Reactive protein 2- Myeloperoxidase 3- homocystiene up to half of the events associated with CVD occur in asymptomatic individuals Inflammation process play prominent role the development and mature athermanous plaque and also contribute to the destabilization of vulnerable plaque resulting in (ACS).

47 C-Reactive Protein Pentameric structure consisting of five 23-kDa identical subunits Produced primarily in hepatocytes Plasma levels can increase rapidly to 1000x baseline levels in response to acute inflammation Positive acute phase reactant

48 C. Reactive protein : CRP is an acute phase reactant, produced in the liver in response to interleukin-6 (IL6) it is highly stable pentameric protein and its serum concentration can increase during acute phase. loss of the pentameric symmetry of CRP result in modified or monomeric form (M-CRP) which may be the major promoter of the pro inflammatory response in coronary arteries. Plays an active role in atherogenesis.

49 CRP and CV Risk Elevated levels predictive of: 1. Long-term risk of first MI 2. Ischemic stroke 3. All-cause mortality

50 Natriuretic peptides Atrial natriuretic peptide (ANP) B type natriuretic peptide (BNP) C type natriuretic peptide D type natriuretic peptide All hormones function in the homeostasis of sodium and water retention

51 Myeloperoxidase Released by activated leukocytes at elevated levels in vulnerable plaques Predicts cardiac risk independently of other markers of inflammation May be useful in triage of ACS (levels elevate in the 1 st two hours) Also identifies patients at increased risk of CV event in the 6 months following a negative troponin

52 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, or smoking

53 Homocysteine 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

54 Homocysteine Elevated levels appear to be an independent risk factor, though less important than the classic CV risk factors Screening recommended in patients with premature CV disease (or unexplained DVT) and absence of other risk factors Treatment includes supplementation with folate, B6 and B12

55 Glycogen phosphorylase BB (GPBB) Heart and brain tissue Because of the blood brain barrier, GP-BB can be heart muscle specific A rapid rise in blood levels can be seen in myocardial infarction and unstable angina. GP-BB elevated 1 3 hours after process of ischemia. Early diagnosis in acute coronary syndrome. High specificity and sensitivity

56 Plaque rupture markers 1- soluble CD 40 ligand 2- placental growth factor 3- pregnancy assciated plasma protien

57 1- soluble CD40 ligand rapidly regulated in fresh thrombus. > 95 percent drived from platelets. Associated with increased risk in apparently healthy woman. Chronic elevations possible due to shedding into plasma from unstable atherosclerotic plaque.

58 2- placental groth factor (PCGF) PCGF stimulates angiogenesis vascular groth factor (VEGF). Play an essential role in both physiologic and pathologic angiogenesis. key role in atheroma expansion. Upregulated in ischemic myocardium.

59 3-Pregnancy assocoiated plasma prenecrosis protien ischemia ( PAPP-A) markers 1- free fatty acids unboud to albumin Abundantly expressed in eroded and ruptured plaques. FFAU Increased level in hyper cholineesterolemia cholineand WBCHO coronary atherosclerosis, even in asymptomatic patients 2- whole blood choline and plasma 3- ischemia modified albumine IMA

60 whole blood choline and plasma choline WBCHO Increased rapidly after stimulation of Phospholipase of plaque destabilization For AMI : Sens : 40 % Speci : 78 % For unstable angina Sens : 86 % Speci : 86 %

61 Ischemia-Modified Albumin (IMA) Under conditions of ischemia, albumin undergoes a conformational change, so that it can no longer bind to transitional metals such as copper or cobalt Albumin cobalt binding (ACB) test Using the albumin cobalt binding test, the proportion of albumin modified by ischemia can be estimated A

62 AMI rises within minutes of ischemia, stays up for 6-12 hrs. normal within 24 hrs. low specificity and sensitivity, also found in ca, liver disease, ESRD, brian ischemia. predictor of long-term outcome in patients with acute myocardial infarction

63 IMA is a marker of ischemia

64 Ischemia-Modified Albumin (IMA)

65 BIOCHEMICAL MARKERS IN ACS: RELEASE, PEAK AND DURATION OF ELEVATION Marker start Peak Duration of elevation LD h h 7 10 days Total CK 3 8 h h 3 4 days CK-MB 4 6 h 24 h h CK-MB isoforms 2 3 h 18 h < 24 h ctni 6 h 24 h 7 10 days ctnt 6 h h 7 10 days Myoglobin 2 h 6 7 h 24 h IMA Few minutes 2 4 h 6 h

66 The Future of Cardiac Biomarkers Many experts are advocating the move towards a multimarker strategy for the purposes of diagnosis, prognosis, and treatment design

67 Why do we need multiple Markers? No single ideal marker exists for ACS Complicated diseases are not likely to be associated with single markers Multiple markers define disease categories Multi-marker panels can aid in differential diagnosis

68 assays for cardiac biomarkers group discussion from your own practice and knowledge state the different assays, methodology and equipments used at the past and present

69 past assays enzyme activity, photometric present: troponin,immunological immunofluorescence assay

70 CASE STUDY A 48-year-old woman was seen by her primary physician for a routine physical examination.her father and his brother died before the age of 55 with AMI and another uncle had CABG surgery at age of 52. Because of this family history, she requested any testing that might indicate a predisposition or increased risk factors for early cardiac disease. She does not smoke, does not have any hypertension, is approximately 20Ib overweight, and exercises moderately. The following test results were obtained.

71 Total cholesterol (<200 mg/dl) 187 mg/dl HDL cholesterol (30-75 mg/dl) LDL cholesterol ( mg/dl) Lipoprotein (a) (<30 mg/dl) Triglycerides ( mg/dl) Glucose ( mg/dl) Total CK ( IU/L) CK-MB (<8 IU/L) % CK-MB (0%-6%) Homocysteine (<15 µmol/l) Fibrinogen (2-4.5 mg/dl) D-dimer (0-250 µg/ml( hscrp ( mg/dl) 52 mg/dl 95 mg/dl 34 mg/dl 203 mg/dl 83 mg/dl 65 IU/L 1.9 IU/L 3 18 µmol/l 4.3 mg/dl 160 µg/ml 0.91 mg/dl

72 Questions 1 Do any of the results obtained indicate a high risk for development of cardiac disease? If so, which result? 2 Does this patient have risk factors for early cardiac disease that can be modified by diet or lifestyle modifications? 3 Is there any specific treatment that can be instituted to reduce this patient s risk? 4 How should this patient be monitored?

Biomarkers of myocardial infarction. Dr. Mamoun Ahram Cardiovascular system, 2013

Biomarkers of myocardial infarction Dr. Mamoun Ahram Cardiovascular system, 2013 References This lecture Hand-outs Acute Myocardial Infarction A rapid development of myocardial necrosis caused by prolonged