Cardiac Markers
Unstable angina
prolonged or recurrent pain at rest caused by disruption of an atherosclerotic plaque with superimposed thrombosis Also caused by embolization or vasospasm
Identify five characteristics of cTnT and cTnI that make them useful biomarkers for acute myocardial infarction
1. They are specific for cardiac muscle tissue. 2. They have high values for diagnostic specificity and sensitivity. 3. They possess early release kinetics after an AMI. 4. They remain elevated for a long interval of time. 5. They have extremely low to undetectable concentration in serum from healthy individuals without ACS or CVD.
Which agent is released or secreted after a hemorrhage and causes an increase in renal Na+ reabsorption? A) Aldosterone B) Angiotensin I C) Angiotensinogen D) Antidiuretic hormone (ADH) E) Atrial natriuretic peptide
A) Aldosterone Angiotensin I and aldosterone are increased in response to a decrease in renal perfusion pressure. Angiotensinogen is the precursor for angiotensin I. Antidiuretic hormone (ADH) is released when atrial receptors detect a decrease in blood volume. Of these, only aldosterone increases Na+ reabsorption. Atrial natriuretic peptide is released in response to an increase in atrial pressure, and an increase in its secretion would not be anticpated after blood loss
When myocardial infarction occurs, the first enzyme to become elevated is: a) CK b) LD c) AST d) ALT
A) CK After an acute myocardial infarction (AMI), CK activity increases 4-6 hours after onset of symptoms, peaks at 12-24 hours and returns to normal within 48-72 hours. AST increases 6-8 hours after the infarction. Elevated levels of LD are noted 12-24 hours after the symptoms. ALT activity does not increase with a AMI
When myocardial infarction occurs, the first enzyme to become elevated is: A) CK B) LD C) AST D) ALT
A) CK After an acute myocardial infarction (AMI), CK activity increases 4-6 hours after the symptoms, peaks at 12-24 hours and returns to normal within 48-72 hours. AST increases 6-8 hours after the infarction. Elevated levels of LD are noted 12-24 hours after the symptoms. ALT activity does not increase with an AMI [Bishop 2018, p270]
In the immunoinhibition phase of the CKMB procedure: A) M subunit is inactivated B) B subunit is inactivated C) MB is inactivated D) BB is inactivated
A) M subunit is inactivated In the immunoinhibition technique for CKMB determination, antibodies are directed against the M and B units of the enzymes. Anti-M inhibits all M activity but not B activity. CK activity is measured before and after inhibition. The activity remaining after inhibition is a result of the B subunit for BB and MB activity. [Bishop 2018, p271]
A patient has a plasma CK-MB of 14ug/L at admission and a total CK of 170 IU/L. Serum myoglobin is 130ug/L and TnI is 1.6ug/L. Three hours later, the TnI is 3.0ug/L. Which statement best describes this situation? A) This patient has had an AMI and further testing is unnecessary B) A second CK-MB and myoglobin test should have been performed at 3 hours postadmission to confirm AMI C) These results are consisten with skeletal muscle damage associated with a crush injury that elevated the CK-MB D) Further testing 6-12 hours postadmission is required to establish a diagnosis of AMI
A) This patient has had an AMI and further testing is unnecessary Results on admission indicated strongly that the patient has suffered an AMI. The 3-hour TnI confirms this and rules out the possibiility of a sample collection error for the admission sample. Repeat testing of other cardiac markers at 3 hours was not necessary because admission results were significantly increased for all three markers. Skeletal muscle damage or crush injury does not cause an increase in cardiac TnI.
A healthy 35-year-old man is running a marathon. During the run, there is an increase in splanchnic vascular resistance. Which receptor is responsible for the increased resistance? A) alpha1 receptors B) beta1 receptors C) beta2 receptors D) Muscarinic receptors
A) alpha1 receptors During exercise, the sympathetic nervous system is activated. The observed increase in splanchnic vascular resistance is due to sympathetic activation of alpha1 receptors on splanchnic arterioles.
In a nonmyocardial as opposed to a myocardial cause of an increased serum or plasma CK-MB, which would be expected? A) an increase in CK-MB that is persistent B) an increase in the percent CK-MB as well as concentration C) The presence of increased TnI D)A more modest increase in total CK than CK-MB
A) an increase in CK-MB that is persistent Plasma CK-MB becomes abnormal 4 hours postinfarction, peaks in 16-20 hours, and usually returns to normal within 48 hours. In some noncardiac causes of elevated plasma CK-MB such as muscular dystrophy, there is a persistent elevation of both total CK and CK-MB. TnI and TnT are cardiac specific markers. They become elevated slightly before CK-MB when a CK-MB URL of 4ug/L is used, remain elevated for 7-10 days following an AMI, and are not increased in muscular dystrophy, malignant hyperhtermia, or crush injuries that are associated with an increase in the concentration of CK-MB. Absolute CK-MB increases are evaluated cautiously, when CK-MB is less than 2.5% of total enzyme because noncardiac sources may be responsible.
An electrophoretic seperation of lactate dehydrogenase isoenzymes that demonstrates an elevation in LD-1 and LD-2 in a "flipped" pattern is consistent with: A) myocardial infarction B) viral hepatitis C) pancreatitis D) renal failure
A) myocardial infarction The major LDH isoenzymes in the serum of healthy persons are LD2, accounting for 29-39% of the total activity and LD1=14-26% of enzyme activity. In a myocardial infarction the pattern is changed. The activity of the LD1 is greater than LD2 and the ratio of LD1 to LD2 is >1. This is known as a "flipped pattern". The normal ratio is 0.45-0.74 [Bishop 2018, p273]
Identify a significant advantage and disadvantage of measuring serum myoglobin in patients complaining of chest pain with a suspected AMI
Advantage: Myoglobin is released early in the blood following an AMI and rises quickly above normal concentrations in such events. Disadvantage: Myoglobin is found in many other tissues throughout the body, including skeletal muscle, so it is not a highly specific test for a possible AMI.
Which of the following represents the correct sequence for the rise and fall of myoglobin, CK-MB, and cTnI after an AMI? a. CK-MB, cTnI, myoglobin b. cTnI, CK-MB, myoglobin c. Myoglobin, CK-MB, cTnI d. CK-MB, myoglobin, cTnI
C
A patient's CK-MB is reported as 18 μg/L and the total CK as 560 IU/L. What is the CK relative index (CKI)? A) 0.10% B) 3.2% C) 10.0% D) 30.0%
B) 3.2% The CKI is an expression of the percentage of the total CK that is attributed to CK-MB. CKI = [ (CK-MB in ug/L)/ (Total CK in IU/L) ] X 100 The reference range is 0%-2.5%. Values above 2.5% point to an increase in CK-MB from cardiac muscle.
What is the HDL cholesterol cutpoint recommend by NCEP? A) < 30mg/dL B) <40mg/dL C) <30mg/dL for males and <40mg/dL for females D) <45 mg/dL for males and <50mg/dL for females
B) <40mg/dL The HDL cholesterol cutpoint recommended by NCEP is <40mg/dL regardless of sex. A result below 40mg/dL counts as a risk factor for coronary artery disease. Conversely, if the HDL cholesterol is >60mg/dL, then one risk factor is subtracted from the total number. The therapeutic goal for someone with low HDL cholesterol is still reduction of LDL cholesterol (if elevated), weight loss, and increased exercise.
Which statement accurately describes serum transaminase levels in AMI? A) ALT is increased 5- to 10-fold after an AMI B) AST peaks 24-48 hours after an AMI and returns to normal within 4-6 days C) AST levels are usually 20-50 times the upper limit of normal after an AMI D) Isoenzymes of AST are of greater diagnostic utility than the total enzyme level
B) AST peaks 24-48 hours after an AMI and returns to normal within 4-6 days ALT may be slightly elevated after an AMI. AST levels can be up to 5-10 times the URL after AMI, but elevations of this range are also seen in patients with muscular dystrophy, crush injury, pulmonary embolism, infectious mononucleosis, and cancer of the liver
The presence of which of the following isoenzymes indicates acute myocardial damage? A) CKMM B) CKMB C) CKBB D) none
B) CKMB The 3 CK isoenzymes are CK1 or CKBB, CK2 or CKMB, CK3 or CKMM. CKMB is primarily located in myocardial tissue. Damage to the myocardial tissue will cause an elevation of the CKMB level. [Bishop 2018, p268-270]
Which statement best describes the clinical utility of plasma homocysteine? A) Levels are directly related to the quantity of LDL cholesterol in plasma B) High plasma levels are associated with atherosclerosis and increased risk of thrombosis C) Persons hwo ahve an elevated plasma homocysteine will also have an increased plasm Lp(a) D) Plasma levels are increased only when there is an inborn error of amino acid metabolism
B) High plasma levels are associated with atherosclerosis and increased risk of thrombosis Homocysteine includes the monomeric amino acid as well as the dimers such as homocystine that contain homocysteine. Plasma levels are measured as an independent risk factor for coronary artery disease. High levels of homocysteine are toxic to vascular endothelium and promote inflammation and plaque formation. Plasma levels are independent of LDL and other cholesterol fractions and help explain why approximately 35% of people with first-time AMI have LDL cholesterol levels <130mg/dL.
A 56-year-old man with a history of stable angina was seen in the emergency department 1 hour following the onset of unrelenting substernal pain not relieved by nitroglycerin. An electrocardiogram (ECG) revealed deep Q waves across the precordium, ST segment elevations, and inverted T waves. Serum levels of creatine kinase MB (CK-MB) and cardiac troponin I (cTn-I) were within normal range. What is the best explanation for these findings? A) Lactate dehydrogenase (LDH) should have been ordered rather than CK-MB and cTn-I B) The diagnosis is acute myocardial infarction (MI), and CK-MB and cTn-I were determined too early in the course of the disease C) The diagnosis is unstable angina rather than acute MI D) The findings are indicative of a dissecting aneurysm (dissecting hematoma) of the aorta E) CK-MB alone can be misleading, and more definitive information would have been expected from total CK determination.
B) The diagnosis is acute myocardial infarction (MI), and CK-MB and cTn-I were determined too early in the course of the disease Persistent chest pain unrelieved by nitroglycerin and the abnormal ECG findings are diagnostic of MI. It would be unusual to observe significant elevations of CK-MB and cTn-I as early as 1 hour following an MI. These markers rise in parallel and are weakly positive in about 6 hours and reach peak levels in about 10 to 15 hours following an MI. CK-MB returns to normal in 3 to 7 days cTnI can remain elevated a week or longer.
What is the recommended troponin T and I cutoff (upper limit of normal) for detecting myocardial infarction? A) The cutoff varies with the method of assay but should be no lower than 0.2ng/mL B) The upper 99th percentile or lowest level that can be measured with 10% CV C) The concentration corresponding to the lowest level of calibrator used D) The highest value fitting under the area of the curve for the 95% confidence interval
B) The upper 99th percentile or lowest level that can be measured with 10% CV The American College of Cardiology recommends the cutoff for an abnormal troponin test be set at the 99th percentile of the normal population, 0.013ng/mL, or if the assay precision at this level is >10% then the cutoff should be the lowest valuable measurable with a CV of 10% (typically 0.03ng/mL) An abnormal result (0.04ng/mL or higher) in a patient with other evidence of ischemic changes indicates cardiac damage. This typically occurs when a pattern of increasing troponin concentration is seen over the first 6 hours after initial testing.
Which of the following cardiac markers is consistently increased in persons who exhibit unstable angina? A) Troponin C B) Troponin T C) CK-MB D) Myoglobin
B) Troponin T Persons with unstable angina (angina at rest) who have an elevated TnT or TnI are at 8 times greater risk of having an MI within the next 6 months. This property is being used to identify short-term risk patients whoe shoudl be considered for coronary angioplasty. The reference range for troponin is very low (0---0.03ng/mL); persons with unstable angina usually have values between 0.04 and 0.1ng/mL without clinical evidence of AMI. CK-MB and myoglobin have not been useful in identifying persons with unstable angina
A 65-year-old man on the fifth day of hospitalization for an acute anterior myocardial infarction has recurrence of chest pain and an increase in both CKMB and troponins I and T. Examination of the heart and lungs is normal. Which of the following is most likely responsible for the laboratory test abnormalities? A) Myocardial rupture B) Papillary muscle dysfunction C) Reinfarction D) Right ventricular infarction E) Ventricular aneurysm
C) (reinfarction is correct). CK-MB isoenzymes, a marker for acute myocardial infarction, are usually gone by 3 days. Therefore, the reappearance of CK-MB after 3 days indicates reinfarction or further extension of an existing myocardial infarction. Troponin I and T are the gold standard for diagnosing an acute myocardial infarction. However, Troponin I remains increased for a week, while Troponin T remains increased for 10 to 14 days; therefore, they cannot be used to diagnose a reinfarction. (myocardial rupture) is incorrect. Rupture of the myocardium either produces a murmur (e.g., mitral regurgitation from posteromedial papillary muscle infarction) or cardiac tamponade with muffling ot the heart sounds and jugular neck vein distension. These are not present in the patient. (papillary muscle dysfunction) is incorrect. The posteromedial papillary muscle is supplied by the right coronary artery. Dysfunction or infarction due to thrombosis of the artery should produce the pansystolic murmur of mitral valve regurgitation. Cardiac examination is normal in the patient. (ventricular aneurysm) is incorrect. Ventricular aneurysms are a late finding in an acute myocardial infarction. They do not produce reappearance of CK-MB
Which of the following statements regarding total CK is true? A) Levels are unaffected by strenuous exercise B) Levels are unaffected by repeated intramuscular injections C) Highest levels are seen in Duchenne's muscular dystrophy D) The enzyme is highly specific for heart injury
C) Highest levels are seen in Duchenne's muscular dystrophy Total CK is neither senisitive nor specific for AMI. AN infarct can occur without causing an elevated total CK. Exercise and intramuscular injections cause a significant increase in total CK. Crush injuries and muscular dystrophy can increase the total CK up to 50 times the URL.
Which statement best describes the clinical utility of B-type natriuretic peptide (BNP)? A) Abnormal levels may be caused by obstructive lung disease B) A positive test indicates prior myocardial damage caused by AMI that occurred within the last 3 months C) A normal test result (<100pg/mL) helps rule out congestive heart failure in persons with symptoms associated with coronary insufficiency D) A level above 100pg/mL is not significant if evidence of congestive heart failure is absent
C) A normal test result (<100pg/mL) helps rule out congestive heart failure in persons with symptoms associated with coronary insufficiency B-type natriuretic peptide is a hormone produced by the ventricles in response to increased intracardiac blood volume and hydrostatic pressure. It is formed in the heart from a precursor peptide (preproBNP) by enzymatic hydrolysis, first forming proBNP follwoed by BNP and NT (N-terminal) proBNP which is not physiologiclaly active. Both BNP and NT-proBNP are increased in persons with congestive heart failure (CHF). Levels are not increased in pulmonary obstruction, hypertension, edema associated with renal insufficiency, and other conditions that cause physical limitation and symptoms that overlap CHF. At a cutoff of <100pg/mL the BNP test is effective in ruling out CHF. Diagnostic accuracy in distinguishing CHF from nonCHF ranges from 83-95%. In addition, persons with ischemia who have an increased BNP are at greater risk for MI. The NTpro-BNP assay is similar in clinical value, and can be used for persons being treated with nesiritide, a recombinant form of BNP used to treat CHF.
What is the typical time course for plasma myoglobin following an AMI? A) Abnormal before 1 hour; peaks within 3 hours; returns to normal in 8 hours B) Abnormal within 3 hours; peaks within 6 hours; returns to normal in 18 hours C) Abnormal within 2 hours; peaks within 12 hours; returns to normal in 36 hours D) Abnormal within 6 hours; peaks within 24 hours; returns to normal in 72 hours
C) Abnormal within 2 hours; peaks within 12 hours; returns to normal in 36 hours Afer AMI, myoglobin usually rises above the cutoff within 1-2 hours, peak within 8-12 hours and returns to normal within 36 hours. Typically levels reach a peak concentration that is 10-fold the upper reference limit. Since myoglobin is the first marker to become abnormal after an AMI, it should be measured on admission and if negative, again 2 hours later. If both samples are below the cutoff, the probability of an AMI having occurred is low. If the myoglobin is above the cutoff, a cardiac specific marker such as TnI or TnT must be performed at some point to confirm the diagnosis
What is the typical timecourse for plasma TnI or TnT following an AMI? A) Abnormal within 3 hours; peaks within 12 hours; returns to normal in 24 hours B) Abnormal within 4 hours; peaks within 18 hours; returns to normal in 48 hours C) Abnormal within 4 hours; peaks within 24 hours; returns to normal in 1 week D) Abnormal within 6 hours; peaks within 36 hours; returns to normal in 5 days
C) Abnormal within 4 hours; peaks within 24 hours; returns to normal in 1 week Troponin is a complex of three polypeptides that function as a regulator of actin and tropomyosin. The three subunits are designated TnC, TnI, and TnT. All are present in both cardiac adn some skeletal muscles, but cardiac and skeletal isoforms of TnI and TnT can be differentiated by specific antisera. TnI and TnT cardiac isoforms in plasma will at least double within 4-6 hours after MI, peak within 24 hours and usually remain elevated for 7-10 days. TnI and TnT have the same sensitivity, but TnT is more commonly elevated in renal failure patients. Both are increased slightly in unstable angina (chest pain while at rest) and cardiac ischemia.
Which of the following is the most effective serial sampling time for ruling out AMI using both myoglobin and a cardiac specific marker in an emergency department environment? A) Admission and every hour for the next 3 hours or until positive B) Admission, 2 hours, 4 hours, and 6 hours or until positive C) Admission, 3 hours, 6 hours, and a final sample within 12 hours D) Admission and one sample every 8 hours for 48 hours
C) Admission, 3 hours, 6 hours, and a final sample within 12 hours Since the time between the onset of symptoms and arrival in the emergency department is often speculative, serial measurement of cardiac markers is required in order to rule out AMI. Since myoglobin is the first marker to rise after AMI, if used it should be measured on admission. Since TnI, TnT, and CK-MB are more cardiac specific, at least one should be measured starting at 3 hours postadmission. If all results are negative to this point, a final assay should be performed 6-12 hours postadmission to conclusively rule out the possibility of AMI and evaluate the short term risk of AMI
Which of the following laboratory tests is a marker for ischemic heart diseasse? A) CK-MB isoforms B) Myosin light chain 1 C) Albumin cobalt binding D) Free fatty acid binding protein
C) Albumin cobalt binding When heart muscle suffers reversible damage as a result of oxygen deprivation, free radicals are released from the cells and bind to circulating albumin. The albumin is modified at the N-terminus, causing a reduced ability to bind certain metals. This ischemia-modified albumin can be measured by its inability to bind cobalt. An excess of cobalt is incubated with plasma followed by addition of dithioreitol. The sulfhydryl compound complexes with the free cobalt, forming a colored complex. The absorbance of the reaction mixture is directly proportional to the ischemia-modified albumin concentration. In addition to ischemia-modified albumin, glycogen phosphorylase-BB is a marker for ischemia because it is released form heart muscle during an ischemic episode. Myosin light chains and fatty acid-binding protein are released form necrotic heart tissue in the early stages of AMI.
Which of the following statements regarding the clinical use of CK-MB (CK-2) is true? A) CK-MB becomes elevated before myoglobin after an AMI B) CK-MB levels are usually increased in cases of cardiac ischemia C) CK-MB is more specific than myoglobin D) An elevated CK-MB is always accompanied by an elevated total CK
C) CK-MB is more specific than myoglobin Serum myoglobin becomes abnormal within 1-2 hours after an acute myocardial infarction (AMI) before troponin and CK-MB. CK-MB becomes abnormal shortly after troponin I (cTnI) or troponin T (cTnT) when a URL of 4ug/L is used, and peaks at around the same time following AMI. However, cardiac troponins remain elevated significantly longer than CK-MB after AMI, and are not increased in crush injuries. There is less than 5ug/L CK-MB in the serum of healthy adults, while the total CK ranges from 10-110 U/L. Consequently an abnormal CK-MB can occur in the absence of an elevated total CK.
Treatment recommendations for patients with coronary heart disease are based upon measurement of which analyte? A) HDL cholesterol B) Apo-B100 C) LDL cholesterol D) Total cholesterol
C) LDL cholesterol NECP has identified LDL cholesterol as the target of therapy for reducing the risk of heart attack becuase lowering LDL cholesterol has proven to be an effective intervention. The greater the risk of coronary heart disease, the lower the cutpoint fo intervention For persons at high risk ( a 10-year risk of heart attack >20%) the cutpoint is 100mg/dL for initiation of statin therapy. For highest-risk persons (those that have acute coronoary syndrome, and multiple or uncontrolled risk factors) the treatment goal is LDL cholesterol below 70mg/dL
A 45-year-old African American female has been diagnosed and treated for type 2 diabetes for the past five years. She maintains good control of her blood glucose with medication but does not exercise and has gained 12 pounds over the past year. At her next appointment, her physician orders hs-CRP along with blood assays to monitor her diabetes. Laboratory Result: hs-CRP 2.8 mg/L A) At no risk for cardiovascular disease B) Low risk for cardiovascular disease C) Moderate risk for cardiovascular disease D) High risk for cardiovascular disease
C) Moderate risk for cardiovascular disease In 2003 the American Heart Association and the CDC published a set of clinical guidelines for the use of hs-CRP as a marker for cardiovascular disease (CVD) risk. hs-CRP <1 mg/L represents low risk of CVD hs-CRP 1.0-3.0 mg/L represents moderate risk of CVD hs-CRP >3.0 represents high risk of CVD In our case, a hs-CRP of 2.8 mg/L indicates a moderate risk of CVD (1.0-3.0 mg/L).
Situation: An EDTA sample for TnI assay gives a result of 0.04ng/mL (reference range 0---0.03ng/mL). The test is repeated 3 hours later on a new specimen and the result is 0.06ng/mL. A third sample collected 6 hours later gives a result of 0.07ng/mL. The EKG showed no evidence of ST segment elevation (STEMI). What is the most likely explanation? A) A false-positive result occurred due to matrix interference B) Heparin should have been used instead of EDTA, which causes false positives C) The patient has suffered cardiac injury D) The patient has had an ischemic episode without cardiac injury
C) The patient has suffered cardiac injury EDTA is the additive of choice for troponin assays because it avoids microclots that can lead to false positive results when serum of heparinized plasma is used. Spurious false positive caused by matrix effects usually revert to normal when the test is repeated on a new sample. An AMI will cause the TnI to increase in subsequent tests. Results between 0.04-0.10ng/mL are the result of cardiac injury, and indicate either AMI or an increased short-term risk of AMI.
An EDTA blood sample is collected from a nonfasting person for a CBC. The physician collected the sample from the femoral vein because venipuncture from the arm was unsuccessful, he called the lab 15 mins after the sample arrived and requested a lipid study including triglyceride, total cholesterol, HDL, and LDL. Which test results should be used to evaluate the patients risk for Coronary artery disease? A) Total cholesterol and LDL cholesterol B) LDL Cholesterol and triglyceride C) Total cholesterol and HDL cholesterol D) Total cholesterol and triglyceride
C) Total cholesterol and HDL cholesterol NCEP recommends a 12-hour fasting sample when screening patients for risk of coronary artery disease. However, if a fasting sample is unavailable, NCEP recommends performing the total cholesterol and HDL cholesterol becuase these tests are least affected by recent ingestion of food If the total cholesterol is > 200mg/dL or the HDL cholesterol is < 40mg/dL, then testing for LDL cholesterol and triglycerides should be performed when a fasting sample can be obtained. An EDTA plasma sample is acceptable for most enzymatic cholesterol and triglyceride assays
Why is CK-MB less useful than cTnI or cTnT as a biomarker for AMI?
CK-MB is less useful because it is not as specific for heart mus- cle as is cardiac troponin I. CK-MB is found in numerous tissues throughout the body other than the heart.
Angina pectoris
episodic chest pain caused by inadequate oxygenation of the myocardium
Which test becomes abnormal in the earliest stage of the acute coronary syndrome? A) Myosin light chain 1 B) CK-MB isoforms C) Myoglobin D) High-sensitivity C-reactive protein
D) High-sensitivity C-reactive protein The acute coronary syndrome (ACS) refers to the evolution of coronary artery events that lead up to AMI. Coronary artery disease (CAD) begins with formation of a plaque comprised of lipid from dead epithelium that proliferates into the artery lumen. The plaque becomes disrupted and the vessel wall inflamed in the asymptomatic stage of CAD. IF platelet activation occurs and results in thrombosis, blood flow becomes significantly reduced, resulting in angina. This signals the transition to more advanced disease in which ischemia to heart muscle occurs and eventually to AMI. Myoglobin and CK-MB isoforms are not increased until the end stage of ACS. High-sensitivity C-reactive protein (hs-CRP) is an ultrasensitive CRP assay that accurately measures CRP below 1 mg/L. CRP is an acute-phase protein increased in inflammation. Levels of CRP between 3.2-10mg/L signal low-grade inflammation, which occurs in the asymptomatic phase of ACS. Such inflammation occurs when coronary artery plaques become disrupted, and therefore, persons with CAD have a mildly increased CRP are at high risk of diesase progression. Glycogen phosphorylase-BB and albumin cobalt binding are increased by ischemia. Troponins are increased when there is unstable angina and ischemic injury, and indicate an increased risk for AMI.
Which of the following cardiac markers derived from neutrophils predicts an increased risk for myocardial infarction? A) Phospholipase A2 (PLA2) B) Glycogen phosphorylase BB (GPBB) C) Soluble CD40 ligand (sCD40l) D) Myeloperoxidase (MPO)
D) MPO All of the answer choices are markers for acute coronary syndrome and increased risk of AMI. MPO is released from neutrophils and is thought to destabilize the arterial plaque by oxidizing both LDL and HDL and reducing nitric oxide levels in the coronary arteries. Levels in the upper third quartile predict an increased risk of a coronary event even when troponinin is normal. GPBB is released from myocytes early in ischemic episode and becomes abnormal 2 hours after an AMI sCD40l is released from activated platelets and indicates unstable plaque. PLA2 is produced by the arterial wall. It removes a fatty acid from phospholipids and increases the amount of oxidized LDL, leading to foam cell formation. Like hs-CRP, it is a marker for an inflamed plaque
A patient has a plasma myoglobin of 10ug/L at admission. Three hours later, the myoglobin is 14ug/L and the troponin I is 0.02ug/L (reference range 0---0.03ug/L). These results are consistent with which condition? A) Skeletal muscle injury B) Acute myocardial infarction C) Unstable angina D) No evidence of myocardial or skeletal muscle injury
D) No evidence of myocardial or skeletal muscle injury This person displays very low plasma myoglobin (reference range for females is approximately 17-75ug/L). The TnI result is also within normal limits. These results are consistent with baseline levels and no evidence of cardiac or skeletal muscle injury. TnI cutpoints for diagnosis of AMI are dependent upon the method, and may be higher than the upper limit of normal. Troponin results above the upper reference limit but below the cutpoint for AMI indicate myocardial injury and increased risk for AMI.
A 45-year-old male is seen in your office after discharge from the hospital. He suffered an anterior myocardial infarction and is asking you about modifying his risk factors. Which of the following is true? A) smoking is not a risk factor for development of atherosclerotic coronary disease B) hypertension is not a risk factor for development of atherosclerotic coronary disease C) a fasting lipid profile is not important and risk factor modification D) the goal of LDL-lowering should be to a value less than 100 mg/dL E) Diabetes mellitus does not need to be closely monitored
D) the goal of LDL-lowering should be to a value less than 100 mg/dL The goal of LDL-lowering should be less than 100 mg/dL. Risk factor modification for atherosclerotic coronary artery disease is a crucial part of management of any patient who has suffered a myocardial infarction. This patient's risk factor modification would be classified as secondary, because he already has known disease, given the fact that he is severed in infarction. Primary prevention refers to preventing the first event Modifiable risk factors for atherosclerosis include discontinuation of smoking, alteration of obesity, treatment of lipid disorders, treatment of hypertension, and aggressive treatment of diabetes mellitus. Unmodifiable risk factors include age, genetics (family history), and gender. Cholesterol goals for secondary prevention are straightforward. The LDL goal of any patient who has known atherosclerotic coronary disease is to lower the LDL to less than 100 mg/dL. The total cholesterol goal is currently to lower the total cholesterol to less than 200 mg/dL. The benefit of a lower LDL has been clearly shown in multiple large outcome trials. In addition to addressing lipid levels (several therapeutic choices exist, the most effective is the statin drugs), the physician also must aggressively address smoking post myocardial infarction, hypertension, and diabetes mellitus. Control of all these factors can substantially decrease this patient's incidence of a second myocardial infarction. Several medications have been associated with decreased risk of a second myocardial infarction; the most important to our simple aspirin therapy and beta blockade therapy. These drugs must be included in any discussion with the patient of a decreasing his risk factor for a second myocardial infarction. [Braunwald, 15/e, pp 1382-1383 ]
Prinzmental angina
intermittent chest pain at rest caused by vasospasm
Which of the following associations is correct? A) Hypokalemia: shortened Q-T interval B) Hypercalcemia: long Q-T interval C) Hypercalcemia: flattened T waves D) Hypocalcemia: U waves E) Hyperkalemia: Peaked T waves
E) Hyperkalemia: Peaked T waves Electrolyte abnormalities affect various portions of the service ECG. Both hypercalcemia and hypocalcemia affect ventricular repolarization and are thus represented by changes in the QT interval. Hypercalcemia results in a shortened QT interval, whereas hypocalcemia results in a prolonged QT interval. Calcium does not affect the T wave; it specifically changes the ST portion of the QT interval. Hyperkalemia may be represented by very tall Peaked T waves as potassium affects ventricular repolarization. Hypokalemia may be represented by U waves, which are small deflections following the T wave.
Risk for Coronary Heart Disease (CHD) markedly reduced when?
LDL < 100mg/dL
Stable angina
pain that is precipitated by exertion caused by severe narrowing of atherosclerotic coronary vessels
The troponin complex consists of which of the following? a. Troponin A, troponin C, and troponin T b. Troponin I, troponin C, and troponin T c. Troponin M and troponin H d. Troponin MM, troponin MB, and troponin
b
TnT
binds Troponin to tropomyosin, thus attaching the trop complex to the thin filament.
A 65-year old man on the fifth day of hospitalization for an acute anterior myocardial infarction has recurrence of chest pain and an increase in both CK-MB and Troponins I and T. Examination of the heart and lungs is normal. Which of the following is most likely responsible for the laboratory test abnormalities? a) Myocardial rupture b) Papillary muscle dysfunction c) Reinfarction d) Right ventricular infarction e) Ventricular aneurysm
c) Reinfarction CK-MB isoenzymes, a marker for acute myocardial infarction, are usually gone by 3 days. Therefore, reappearance of CK-MB after 3 days indicates reinfarction or further extension of an existing myocardial infarction. Troponins I and T are the gold standard for diagnosing an acute myocardial infarction. However, troponin I remains increased for a week, while troponin T remains increased for 10-14 days; therefore, they cannot be used to diagnose a reinfarction. [Goljian Rapid Review 2010, p285]
Premature atherosclerosis can occur when which of the following becomes elevated: a) chylomicrons b) prostaglandins c) low-density lipoproteins d) high-density lipoproteins
c) low-density lipoproteins Atherosclerosis is characterized by a thickening and hardening of the arterial walls by cholesterol paqes in the lining o fthe arteries. Elevated levels of cholesterol are associated with the development of the plaques. One of the roles of LDL is to transport cholesterol esters to the cells for metabolism Elevated LDL levels are also associated with development of atherosclerosis. [Bishop 2018, p321]
