cardiac biomarker

cardiac biomarker of acs and heart failure

1. Dr RAMDHAN KUMAR KAMAT SR CARDIOLOGY IGIMS PATNA CARDIAC

2. Food and Drug Administration (FDA) first defined a biomarker in 1992 as “a laboratory measure or physical sign that is used in therapeutic trials as a substitute for a clinically meaningful end point that is a direct measure of how a patient feels, functions, or survives and is expected to predict the effect of the therapy. ”

3. Biologic marker (biomarker): A characteristic that is objectively measured and evaluated as an indicator of normal biologic processes , pathogenic processes , or pharmacologic responses to a therapeutic intervention. Surrogate endpoint : A biomarker intended to substitute for a clinical endpoint. A surrogate endpoint is expected to predict clinical benefit (or harm) or lack of benefit (or harm) based on epidemiologic, therapeutic, pathophysiologic , or other scientific evidence. Clinical endpoint : A characteristic or variable that reflects how a patient feels, functions, or survives. Biomarker Definitions

4. CARDIAC BIOMARKERS Cardiac biomarkers are protein /enzyme molecules released into the blood stream from damaged heart muscle . These biomarkers have a characteristic rise and fall pattern .

5. 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 / hSTn 2000

6. Types of Biochemical Markers 1- Cardiac Enzymes ( isoenzymes ): Total CK CK-MB activity CK-MB mass 2- Cardiac proteins: Myoglobin Troponins

7. PATHOPHYSIOLOGY BASIS OF BIOMARKERS Biomarkers of inflammation . C-reactive protein / hsCRP , Homocysteine . Myeloperoxidase (MPO) Soluble fragment CD40 ligand ( sCD40L ) Biomarkers of plaque instability/disruption. Pregnancy-associated plasma protein A (PAPP-A) Choline Placental growth factor MMP-9 Myeloperoxidase ( MPO )

8. Biomarkers of myocardial ischemia . Ischemia-modified albumin (IMA) Free fatty acids unbound to albumin (FFAu) Heart-type fatty acid binding protein (H-FABP) (PRE NECROSIS) Myocardial necrosis c Tn , hscTn CK-MB , myoglobin Pump failure,myocardiac stress Nt-PROBNP,GDF-15,ST-2,ET-1

9. 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

10. The ACC/AHA and European Society of Cardiology (ESC) guidelines recommend cTnI or cTnT as the preferred first-line marker. CK-MB (by mass assay ) is an acceptable alternative. If the initial set of markers is negative, another sample should be drawn 3 to 6 hours later ; if a high-sensitivity assay is used, a 1-hour algorithm can be considered.

11. CARDIAC TRO P ONINS Troponin is a protein complex located on the thin filament of striated muscles consisting of the three subunits namely Troponin T (TnT), Troponin I (TnI) and Troponin C (TnC) each having different structure and function . TnT and TnI are being used as the biochemical markers for the diagnosis of myocardial injury . The troponins found in cardiac tissue (cTn) have a d ifferent amino acid sequence that present in troponin of skeletal muscles . This makes cTnT and cTnI more specific for the diagnosis of myocardial injury. These cardiac troponins (cTns) appear in the blood as early as 3-4 hours of the acute episode and remain elevated for 4-14 days.

12. 16 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 99 th percentile value of reference group . To reduce false-positive outcomes , CV of < 10 % at decision limit is recommended .

13. The pattern of release of troponin may be monophasic or biphasic . This release kinetics is related to the distribution of these proteins within the myocardial cell. About 94-97% of these troponins is bound to myofibril and only 2- 3 % of cTnI and 6% -8% of cTnT is free in the cytoplasm When the myocardial damage occurs the cytosolic troponins reach the blood stream quickly resulting in a rapid peak of serum troponin observed during the first few hours.

14. Studies have shown that cardiac troponins should replace CKMB The reasons being : Troponins are highly cardiospecific especially the TnI (100%). The prolonged elevation ( 4-14 days ) make it a good marker for patients admitted to the hospital after several days of MI. cTns have greater sensitivity for minor degrees of myocardial injury due to the cardiospecificity and their very low concentration in serum of normal individuals. These are excellent prognostic indicator in patients with unstable angina and is a very useful parameter for stratifying risk in acute coronary syndrome(ACS). Rottbauer W, Greten T, Muller-Bard off M et al. Troponin T:A

15. A single measurement of serum cTnT at the time corresponding to the slow continuous release after AMI (~72 hours after onset ) can be used as a convenient and cost effective non-invasive estimate of infarct size whereas CKMB requires repetitive sampling . The early serial measurements of cTnI are a more accurate predictor of early coronary artery reperfusion after thrombolytic therapy as compared to CKMB and myoglobin .

16. According to U.S. National Academy of Clinical Biochemistry (NACB) and Joint European Society of Cardiology and American College of Cardiology (ESC/ ACC) guidelines cTns are the most specific and sensitive biochemical markers.

17. cTnT Versus cTnI Both cTnT and cTnI are almost equally good markers and it is difficulty to say which is better because both have some positive and negative points . cTnI is 100% cardiospecific and it is not elevated in chronic renal disease , trauma and skeletal muscle disease . The overall diagnostic specificity and efficiency of cTnI is better than cTn T.

18. 24 TROPONIN T Cardiac Troponin T (cTnT) is present in fetal skeletal muscle . In healthy adult skeletal muscle cTnT is absent. The gene of cTnT may be re-expressed in skeletal muscle disease. (Clin Chem. 1999;45:2129-2135) Biological half life and early serum increases of cTnT are similar to that of cTnI.

19. cTnI : 100 % cardiac specific With greater sensitivity for diagnosing minor damage of MI. Appears in blood within 4 hours after onset of infarction peak: around 24 hours Disappears from blood after 7-10 days (stays longer). So, useful for diagnosis of delayed admission cases Prognostic marker (relation between level in blood & extent of cardiac damage)

20. 6-8% 2-3%

21. 27 Cardiac Troponin Release after MI

22. COMPARISON NEJM 2002;Vol.346,No.26:2079-82 28

23. The other advantage of cTnI may be its greater specificity in patients of ESRD . However, the important advantage of cTnT is that due to international patent restrictions there is only one assay for its measurement, thus cTnT demonstrates a high degree of precision at the low end of measurement range and a relatively uniform cut-off concentration . In contrast, at least 18 different commercial assays for cTnI are available leading to considerable variation in the cut-off concentrations in the definition of a myocardial infarction by cTnI values . Thus, a clinician should be aware of the cTnI cut-off values specifically associated with the particular assay used by the laboratory.

24. The life-time of cTnT in blood ( 10 - 14 days) is some what more than that of cTnI ( 7 -10 days). Although cardiac troponins are extremely specific for myocardial necrosis , but they do not discriminate between ischaemic and non- ischaemic etiologies of myocardial injury . The recommended time course for collection of blood samples for cTn is at hospital admission, 6 and 12 hours later but when it is used along with an early marker like myoglobin (two-marker strategy) then at hospital admission, 4 , 8 and 12 .

25. WASH-OUT PHENOMENON . Patients with ST-segment elevation myocardial infarction who achieve an effective reperfusion have a greater and earlier peak plasma concentration of troponin, followed by a faster return to normal – the so-called “wash-out phenomenon ” – compared with those patients having no significant reperfusion . In this event, two blood samples should be collected – at the time of the patient's admission to hospital, and 90 min later – and the enzyme plasma concentrations compared . The ratio between the concentrations at these two points can be used to discriminate between successful and unsuccessful reperfusion. In general, the greater the ratio (at least 5), the more likely it is that reperfusion has occurred.

26. AFTER CABG Increase more than 10 x 99 percentile URL during first 72 hrs 5

27. Tn IN ESRD The cardiac troponin especially cTnT pose diagnostic challenges in patients of chronic renal failure . Frequent cTnT elevations ( 30 to 70% of end stage renal disease (ESRD) patients compared with <5% in similar patients of cTnI ) are seen in patients of renal failure in the absence of clinical suspicion of ACS . The putative mechanisms for chronic elevation of troponin in chronic renal disease patients include : endothelial dysfunction, acute cardiac stretch, microinfarction and left ventricular hypertrophy . uremic toxicity

28. Increasing evidence suggests that chronically elevated troponin levels indicate a worse long-term prognosis for cardiovascular outcomes in this patient population False positives have been reported with use of troponin- T in ESRD patients but not as much with troponin-I CK: plasma concentrations are elevated in 30-70% of dialysis patients at baseline, likely secondary to 1. skeletal myopathy , 2. intramuscular injections and 3. reduced clearance. CK-MB : 30- 5 % of dialysis patients exhibit an elevation in the MB fraction . Therefore, the most specific marker for suspected AMI in ESRD patients is Troponin-I .

29. 36 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)

30. hsTn Experts recommend that the term high-sensitivity troponin ( hsTn ) be reserved for assays that can detect cardiac troponin in more than 50% of an apparently healthy population. As high-sensitivity troponin ( hsTn ) assays that can detect ultralow concentrations of troponin .

31. HIGH-SENSITIVITY CARDIAC TROPONIN. High-sensitivity assays deliver more precise measurement of very low concentrations of cardiaospecific troponin . Such assays have greater sensitivity than previous-generation assays, but also have diminished clinical specificity .

32. High-sensitivity assays likely detect troponin release much earlier than older-generation assays. HsTn assays have improved overall diagnostic accuracy and enabled earlier detection of myocardial injury. Moreover, hsTn assays facilitate the adoption of criteria for rapidly changing concentration of troponin over periods as short as 1 to 3 hours that aid in discriminating acute myocardial injury from chronically elevated values caused by underlying structural heart disease (e.g., left ventricular hypertrophy)

33. Fourth-generation cTn assays currently used in the United States are less sensitive than hsTn assays available in some European countries. Thus, two negative cTn assays at least 6 hours apart are needed to exclude MI with these less sensitive assays.

34. Newer hsTn assays (approved in the United States in 2017), it is possible with a single measurement at presentation of less than 5 ng /L to classify “very low risk” for MI or cardiac death in the next 30 days ( negative predictive value [NPV], 99.6%).

35. Absolute changes in hsTn greater than 9.2 ng /L are even more predictive of acute MI than a single measure or relative changes between two measurements. Use of absolute changes in hsTn allow for rapid protocols as brief as 1 hour to rule in or rule out MI.

36. Rapid Rule-Out of AMI: Serial hscTnT measurements at 0 and 2 hours to evaluate those patients with possible AMI. With hscTnT , the following most often can rule out AMI: Values less than or equal to the sex-specific 99th percentile that we advocate (10 ng /L for women and 15 ng /L for men)

37. Ruling In AMI A rising pattern with at least one value above the 99th percentile URL in patients with evidence of acute ischemia is necessary for the diagnosis of AMI. Individualization is necessary in the elderly, women , and diabetic and postoperative patients who may be pauci -symptomatic. An absolute baseline cut-off value of hscTnT of 52 ng /L has been advocated in the rapid algorithms for the diagnosis of acute myocardial injury. This criterion is reasonable for patients with chest pain, but it will be too low for patients with chronic elevations , the elderly , and those who are critically ill. Cut-off value of 100 ng /L as diagnostic for acute myocardial injury in the absence of end-stage renal disease.

38. Change criteria have also been advocated to diagnose acute myocardial injury. A change of 50% or more predicated on the reference change interval (the change in values that guarantees the change is not due to variation alone) has been suggested when baseline values are near the 99th percentile URL. However, when the baseline value is elevated , changes of only 20% are recommended to maintain sensitivity. 

39. DRAWBACK

40. CK - MB If a cardiac-specific troponin assay is not available , CK-MB measured with a mass assay is the best alternative. Cardiac muscle contains both the MM and the MB isoenzyme of CK. Other tissues can contain small quantities of CK-MB, including the small intestine , tongue, diaphragm , uterus , and prostate . Strenuous exercise, particularly in trained long-distance runners or professional athletes , can elevate both total CK and CK-MB. Because CK-MB can be detected in the blood of healthy persons, the cutoff value for abnormal elevation of CK-MB is usually set a few units above the upper reference limit .

41. Creatine kinase (CK) is a cytosolic enzyme CK is a dimer composed of two subunits B ( brain type) and M (muscle type), resulting in three isoenzyme: CK-BB (CK1) : is of brain origin, found in blood only when BBB is damaged . CK-MB (CK2) : it is relatively specific for myocardial origin . CK-MM (CK3) : it is found primarily in skeletal muscle . CK - MB

42. Total CK (sum of CK-MM, CK-MB & CK-BB) non specific to cardiac tissue (available in skeletal ms. ) CK-MB ( CK-2 ) activity More specific than total CK BUT : less specific than troponin I (available in sk. Ms) Appears in blood: within 4-6 hours of onset of attack Peak: 12 - 24 hours Returns to normal: within 2 - 3 days (no long stay in blood) Advantages : - useful for early diagnosis of MI - useful for diagnosis reinfarction Disadvantages : not used for delayed admission (more than 2 days) Not 100% specific (elevated in sk.ms damage )

43. CK-MB mass - appears one hour earlier than CK-MB activity ( more sensitive ) - So, useful for diagnosis of early cases & reinfarction . - BUT: not for diagnosis of delayed admission cases & less specific than troponin I Relative index = CK-MB mass / Total CK X 100 more than 5 % is indicative for MI

44. 52 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…

45. Small-size heme protein found in all tissues mainly assists in oxygen transport It is released from all damaged tissues Its level rises more rapidly than cTn and CK-MB. Released from damaged tissue within 1 Hr Normal value: 17.4-105.7 ng/ml T iming: Earliest Rise: Peak Return to normal: 1-4 hrs 6-9 hrs 12 hrs Myoglo b in

46. CONDITIONS FOR MYOGLOBIN INCREASE : Acute myocardial infarction Skeletal muscle damage, muscular dystrophy, inflammatory myopathies Renal failure, severe uremia Shock and trauma

47. Clinical usefulness of myoglobin : I f myoglobin concentration remains within the reference range 8 hours after the onset of chest pain, AMI can be ruled out essentially . DRAWBACKS Due to poor specificity, myoglobin levels do not always predict myocardial injury

48. 2 3 4 7 6 5 myogl o b i n CK-MB cTnT cTnI C OMPARISON OF C T N , CK-MB , M B 1 0 4 8 1 2 1 6 2 2 4 2 8 3 2 3 6 4 4 4 48 Time after onset of AMI (hours) Χ upper limit of reference interval

49. Other Biomarkers C-reactive protein (CRP) rises substantially in the setting of STEMI as a result of the inflammatory response to myocyte necrosis and is associated with the subsequent risk for death or HF. Natriuretic peptides reflect the hemodynamic impact of the MI and are associated with prognosis. Although both natriuretic eptides and CRP enhance risk assessment , no clear guidance is available on how to direct specific therapeutic maneuvers in the setting of STEMI based on these biomarkers.

50. Growth differentiation factor-15 , ST2 , fibroblast growth factor-23 , and galectin-3 are also biomarkers that may putatively reflect myocardial ischemia or its consequences and have been associated with CV outcomes in clinical studies of patients with SIHD. Other novel biomarkers of hemodynamic stress , such as midregional pro- adrenomedullin (MR- proADM ) and midregional pro– atrial natriuretic peptide .

51. Biomarkers of inflammation, such as interleukin-6, myeloperoxidase , growth factors , cytokines , and metalloproteinases , remain under study as potential biomarkers.

52. Genetic and Transcriptomic Biomarkers It is now also possible to study multigene expression from peripheral blood cells, so called transcriptomics . For example, a peripheral blood gene expression score based on expression values for 23 genes from peripheral blood cells has been developed and validated to assess the risk for obstructive CAD ; a high negative predictive value (NPV) with a very low rate of major adverse cardiac events (MACE) over a 1-year period was demonstrated in patients with a low gene expression SCORE

53. Multimarker approaches (e.g., simultaneous assessment of cTn , hs -CRP , and BNP ) can further improve risk stratification of patients with NSTE ACS. While lipid measurements are less helpful for individual prognostication assessment of the low-density lipoprotein cholesterol (LDL-C) and triglycerides , along with glucose or hemoglobin ( Hb ) A1c can identify uncontrolled risk factors that with proper management, could reduce the risk of future CV events.

54. BIOMARKERS OF HEART FAILURE (HF)

55. Biomarkers Used in Assessing Patients with Heart Failure

56. Inflammatory Mediators and Markers of Oxidative Stress : Toll-like receptor molecule: The increased into the circulation of toll-like receptor molecules makes them potentially useful as biomarkers that can be used to assess risk and to provide important insights into the mechanisms involved in the pathogenesis of HF. Cytokines: The mediators that have proved most useful as biomarkers in HF include the proinflammatory cytokines, t umor necrosis factor-alpha , interleukin (IL)-1, IL-6 , growth differentiation factor 15 ( GDF-15 ), and C-reactive protein (CRP). Suppressor of tumorgenicity 2 (ST2) concentrations are elevated in HF. Galectin-3 (gal-3), a β- galactoside –binding lectin member of the galectin family, is another biomarker of inflammatory response in HF. BIOMARKERS FOR PREVENTION, ASSESSMENT, AND MANAGEMENT OF HEART FAILURE

57. Myocyte Injury and Stress: Release of troponin T ( TnT ) and troponin I ( TnI ) occurs in HF in the absence of an acute coronary event. BNP and its amino terminal NT-BNP are released into circulation directly from the myocardium as a result of end-diastolic stress as results of increases in volume or pressure.

58. Assessing Risk of Incident HF BNP and NT- proBNP have the best predictive value. In community-based populations, measurement of natriuretic peptides (BNP or NT- proBNP ) or markers of myocardial injury ( TnI or TnT ) alone adds prognostic information to standard risk factors for predicting new-onset HF. Renal dysfunction as reflected by creatinine or cystatin -C is a strong predictor of new-onset HF. Gal-3, sST2 , and GDF-15 collectively have shown to have additive prognostic value in risk models for new-onset HF. Therefore, measurement of several new biomarkers, including sST2 , Gal-3, GDF-15 , and markers of renal function, alone or in a multimarker strategy , may be useful for providing additional risk stratification.

59. Biomarkers for Diagnosis of HF: BNP diagnoses HF in patients presenting to the emergency department with shortness of breath, with a sensitivity of 90% and specificity of 76% at a cut-off value of 100 pg/ml ; the proposed rule-in cutoff is >400 pg/ml. For NT- proBNP to improve, positive predictive value age-related cut-offs of 450 pg/ml for <50 years, 900 pg/ml for 50-75 years, and 1800 pg/ml for >75 years are recommended. Cautious interpretation of concentrations is important in the presence of confounders such as age; obesity; and cardiac, pulmonary, and renal disease.

60. Circulating levels of natriuretic peptides are elevated in HF with preserved ejection fraction ( HFpEF ), but are lower in concentrations than in patients with HFrEF . To support the diagnosis of HFpEF , partition values for diagnosis are a BNP ≥100 pg/ml and NT- proBNP ≥800 pg/ml . Changes in microRNA 29a, and 133a are associated with myocardial fibrosis in patients with HFpEF , but these have not been applied as diagnostic or prognostic biomarkers in such patients.

61. Biomarkers for Prognosis of Chronic HF: Elevated BNP or NT- proBNP parallel HF disease severity, assessment of New York Heart Association (NYHA) class, elevated filling pressures, or worse hemodynamics are suggestive of worse clinical outcomes and mortality in HF. Each increase in BNP by 100 pg/ml is associated with a 35% increase in relative risk of mortality (95% confidence interval [CI], 22-49; p = 0.096). Detectable levels of hs-Tn level predict worse outcomes including mortality (hazard ratio, 2.08; 95% CI, 1.72-2.52) at 2 years.

62. Biomarkers for Prognosis of Acute HF In patients with acutely decompensated HF , measurement of BNP or NT- proBNP and cardiac Tn at the time of presentation is useful for establishing prognosis or disease severity. Predischarge BNP and NT-pro-BNP are stronger markers of post-discharge outcomes than either baseline or percent change in BNP during hospitalization.

63. Outpatient Management of HF Biomarker–guided, with either BNP- or NT- proBNP , HF therapy is of uncertain benefit in clinical practice and therefore not advised. The utility of serial measurement of BNP or NT- proBNP to reduce HF hospitalization or mortality is not well established .