Clinic Laboratory Tests in Clinic Laboratory Tests in Cardiac DiseaseCardiac Disease

Prof. Dr. ARZU SEVENProf. Dr. ARZU SEVEN

Cardiac markers should be:Cardiac markers should be: absolutely heart specificabsolutely heart specific highyl sensitivehighyl sensitive able to differentiate irreversible damage from able to differentiate irreversible damage from

reversiblereversible able to detect reocclusion and reinfarctionable to detect reocclusion and reinfarction able to monitor reperfusion therapy able to monitor reperfusion therapy

able to estimate size of infarct and prognosisable to estimate size of infarct and prognosis stablestable able to make measurements rapidlyable to make measurements rapidly easy to performeasy to perform cost effectivecost effective

Ruling out AMI requires a test with high diagnostic Ruling out AMI requires a test with high diagnostic

sensitivity.sensitivity.

Ruling in AMI requires a test with high specificity.Ruling in AMI requires a test with high specificity.

A single test that will quickly and accurately assess A single test that will quickly and accurately assess

AMI (acute myocardial infarction) does not existAMI (acute myocardial infarction) does not exist..

A combination of markers is used :A combination of markers is used :

An early marker that increases within 6 hr. An early marker that increases within 6 hr.

after onset of symptoms after onset of symptoms

A definite marker that increases after 6-9 hrs. A definite marker that increases after 6-9 hrs.

and remains high for several daysand remains high for several days

Enzymes as Cardiac Markers Enzymes as Cardiac Markers Creatine kinase (CK or CPK) Creatine kinase (CK or CPK)

AspartatAspartatee amino transferase (AST) amino transferase (AST)

Lactate dehydrogenase (LDH or LD)Lactate dehydrogenase (LDH or LD)

Creatine KinaseCreatine Kinase A cytoplasmic and mitochondriac enzymeA cytoplasmic and mitochondriac enzyme Total CK is %40 sensitive and %80 specific Total CK is %40 sensitive and %80 specific

CK-1(BB) : BrainCK-1(BB) : Brain CK-2(MB) :MyocardiumCK-2(MB) :Myocardium CK-3(MM) :Skeletal muscle ,heartCK-3(MM) :Skeletal muscle ,heart

CK-3 has 3 isoforms :CK-3CK-3 has 3 isoforms :CK-311, CK-3, CK-322 and CK-3 and CK-333

(posttranslational products)(posttranslational products) CK-2 has 2 isoformsCK-2 has 2 isoforms

Half life :CKHalf life :CK--3311 > CK-3 > CK-322>CK-3>CK-333, CK-2, CK-211>CK>CK--2222

CK-MB (CK-2) has the most specificity for CK-MB (CK-2) has the most specificity for cardiac muscle (>%85)cardiac muscle (>%85)

CK-MB (CK-2) accounts for only 3-20 % of total CK-MB (CK-2) accounts for only 3-20 % of total CK activity in heartCK activity in heart

Normal skeletal muscle contains 1 % CK-2Normal skeletal muscle contains 1 % CK-2

CK-2 is increased inCK-2 is increased in s severe skeletal muscle injury evere skeletal muscle injury (trauma/surgery ),chronic muscle disease (muscula(trauma/surgery ),chronic muscle disease (muscularr dystrophy,dystrophy, polymyositis ) and extreme exercise.polymyositis ) and extreme exercise.

Reason:Regeneration process of muscle (reexpression Reason:Regeneration process of muscle (reexpression of CK-MB genes )of CK-MB genes )

In AMI,CK-MB increases at least 4-6 hr.after onset of In AMI,CK-MB increases at least 4-6 hr.after onset of chest pain,makes a peak at 12-24 hr.chest pain,makes a peak at 12-24 hr. a and returns to nd returns to baseline level in 2-3 days (baseline level in 2-3 days (t t 1/2 is 10-12 hr )1/2 is 10-12 hr )

Factors that might affect the classic Factors that might affect the classic

pattern :pattern :

1-Size of infarction1-Size of infarction

2-CK-2 composition in myocardium2-CK-2 composition in myocardium

3-Concomitant skelatal muscle injury and3-Concomitant skelatal muscle injury and

reperfusionreperfusion

Differentation of increased CK-2 due to heart Differentation of increased CK-2 due to heart or muscle or muscle monoclonic anti CK-2 antibody monoclonic anti CK-2 antibody based assaysbased assays

%relative index (%RI)= CK-2 activity /total CK X %relative index (%RI)= CK-2 activity /total CK X %100%100

helpful in the detection of AMIhelpful in the detection of AMI

CK-2CK-222: the predominant isoform in blood : the predominant isoform in blood

collected 2-6 hr. after AMI .It makes a peak collected 2-6 hr. after AMI .It makes a peak

≈10-18 hr.,decreases rapidly 12-24 hr ≈10-18 hr.,decreases rapidly 12-24 hr

concomitantly asconcomitantly as CK-2CK-211 gradually increases. gradually increases.

Following trombolitic therapy in AMI Following trombolitic therapy in AMI patients,patients, greater than two fold increases of greater than two fold increases of CK-2 occur within 90 min. of reperfusion CK-2 occur within 90 min. of reperfusion

The rate of which CK-2 isoform is released from The rate of which CK-2 isoform is released from the myocardium to circulation appears to be the the myocardium to circulation appears to be the more useful index of coronary reperfusionmore useful index of coronary reperfusion

CK2CK222 ∕ CK-2 ∕ CK-211 ratio→best discriminant within ratio→best discriminant within

1 hr. after treatment1 hr. after treatment

Lactate Dehydrogenase (LDH)Lactate Dehydrogenase (LDH) A cytoplasmic enzyme found in skeletal, A cytoplasmic enzyme found in skeletal,

muscle, liver, heart, kidney and red blood cells muscle, liver, heart, kidney and red blood cells

5 izoenzymes, composed of 4 subunit 5 izoenzymes, composed of 4 subunit

peptides of 2 distinct types:M (muscle ),peptides of 2 distinct types:M (muscle ), H H

(heart)(heart)

LDH isoenzyme determination increases LDH isoenzyme determination increases

specificity for cardiac tissue.specificity for cardiac tissue. LD1 (HHHH):moves fastest towards anodeLD1 (HHHH):moves fastest towards anode

LD5 (MMMM):moves closest towards cathodeLD5 (MMMM):moves closest towards cathode

LD2 (HHHM )LD2 (HHHM )

LD3 (HHMM )LD3 (HHMM )

LD4 (HMMM )LD4 (HMMM )

LD1 in heart,kidney(cortex),LD1 in heart,kidney(cortex), red blood cellsred blood cells

LD5 in liver,skeletal muscleLD5 in liver,skeletal muscle

In healthy adults:In healthy adults:

14-26 % LD1 (slow removal )14-26 % LD1 (slow removal )

29-39% LD229-39% LD2

20-26% LD320-26% LD3

8-16 % LD48-16 % LD4

6-16 % LD5 (rapid disappearance ) 6-16 % LD5 (rapid disappearance )

Not a tissue specific enzymeNot a tissue specific enzyme In AMIIn AMI total LD -elevation at 12-18 hrtotal LD -elevation at 12-18 hr

peak at 48-72 hr peak at 48-72 hr return to baseline level after 6-10 daysreturn to baseline level after 6-10 days

LD 1 (heart)LD 1 (heart)

elevation at 10-12 hr elevation at 10-12 hr

clinical specificity 85-90 in patients clinical specificity 85-90 in patients

suspected of AMIsuspected of AMI

peak at 72-144 hrpeak at 72-144 hr

return to normal >10 daysreturn to normal >10 days

Total LD patern ≈LD1 pattern (contrast with Total LD patern ≈LD1 pattern (contrast with

total CK and CK-2 pattern)total CK and CK-2 pattern)

Because of its prolonged half life,Because of its prolonged half life, LD-1 is a LD-1 is a

clinically sensitive (%90) marker for infarction clinically sensitive (%90) marker for infarction

when measured after 24 hr.when measured after 24 hr.

LD1∕LD2 >1,0 →FLIPPED PATLD1∕LD2 >1,0 →FLIPPED PATTTERN ERN

(clinical sensitivity %75 ,(clinical sensitivity %75 , clinical specificity clinical specificity

85-90 in patients suspected of AMI)85-90 in patients suspected of AMI)

if CK-2 values are diagnostic for AMI,if CK-2 values are diagnostic for AMI, cancel LD cancel LD

isoenzyme test requestisoenzyme test request,, because LD isoenzyme because LD isoenzyme

results don’t increase the clinical specificity of results don’t increase the clinical specificity of

diagnostic CK-2 results for AMIdiagnostic CK-2 results for AMI

As with CK-2 in skeletal muscle, the heart As with CK-2 in skeletal muscle, the heart

specific LD-1 isoenzyme in skeletal muscle can specific LD-1 isoenzyme in skeletal muscle can

increase twofold during a 9-wk exercise increase twofold during a 9-wk exercise

training,training, with paralel decreases in LD-5with paralel decreases in LD-5

LD and isoenzymes play no role in unstable LD and isoenzymes play no role in unstable

and stable angina.and stable angina.

Aspartate aminotransferase (AST )Aspartate aminotransferase (AST ) WWidely distributed in many tissuesidely distributed in many tissues Highest concentrations are found in cardiac Highest concentrations are found in cardiac

tissue,tissue, liver and skeletal muscle.liver and skeletal muscle. Clinical utility in hepatocellular disorders and Clinical utility in hepatocellular disorders and

skeletal involvement.skeletal involvement. Unuseful in diagnosis of AMIUnuseful in diagnosis of AMI Beginsto rise within 6-8 hr.Beginsto rise within 6-8 hr. Makes a peak at 24 hr.Makes a peak at 24 hr. Generally returns to normal within 5 days.Generally returns to normal within 5 days.

MyoglobinMyoglobin OO22 binding protein of cardiac and skeletal muscle. binding protein of cardiac and skeletal muscle.

Low molecular weight and cytoplasmic location-Low molecular weight and cytoplasmic location-early appearance in circulation after muscle injuryearly appearance in circulation after muscle injury

Cleared rapidly by kidney→unreliable as a long Cleared rapidly by kidney→unreliable as a long term marker of cardiac damageterm marker of cardiac damage

Cardiac muscle trauma, skeletal muscle trauma, Cardiac muscle trauma, skeletal muscle trauma, Crush injury and AMI cause an increase in Crush injury and AMI cause an increase in myoglobin levels.myoglobin levels.

serum myoglobserum myoglobiin methods are unable to n methods are unable to distinguish the tissue of origindistinguish the tissue of origin

referrefereence intervals vary according to age,nce intervals vary according to age, rate rate and sexand sex

1. age 1. age myoglobulin myoglobulin

2. male > female2. male > female

3. black > white3. black > white

very sensitive very sensitive early diagnosticearly diagnostic marker for AMI marker for AMI (%90-100) ,poor clinical specificity (%60-95)(%90-100) ,poor clinical specificity (%60-95)

rises as early as 1 hr. after AMI, peaks in 4-12 hr rises as early as 1 hr. after AMI, peaks in 4-12 hr reflects the early course of myocardial reflects the early course of myocardial necrosis, lasts for 24 hr.necrosis, lasts for 24 hr.

the role of myoglobthe role of myoglobiin in the detection of AMI is n in the detection of AMI is within 0-4hr. (CK-2 is within its reference within 0-4hr. (CK-2 is within its reference level).level).

To improve clinical specificity,carbonic anhydrase To improve clinical specificity,carbonic anhydrase

III (CAIII)III (CAIII) should be measured. should be measured.

After AMI,After AMI, CK-2 and myoglobin increase,but CA III CK-2 and myoglobin increase,but CA III

remains unchanged.In severe skeletal muscle remains unchanged.In severe skeletal muscle

trauma (exercise,trauma (exercise, shock and i.m injection ),shock and i.m injection ), CK-2,CK-2,

myoglobin and CAIII increase.myoglobin and CAIII increase.

If myoglobin remains If myoglobin remains unchanged unchanged and within reference and within reference

levels on multiple,early samplings within 3-6 hr. levels on multiple,early samplings within 3-6 hr. aafter fter

onset of chest pain,there is 100 %certainty that onset of chest pain,there is 100 %certainty that

muscle (either skeletal or cardiac ) injury has muscle (either skeletal or cardiac ) injury has NOTNOT

occurred occurred recently—Negative predictorrecently—Negative predictor

Myoglobin/total CK Myoglobin/total CK >>5 reperfusion indicator (clinical 5 reperfusion indicator (clinical

sensitivity 75 %,clinical specificity 96 % )sensitivity 75 %,clinical specificity 96 % )

Cardiac TroponinsCardiac Troponins Contractile proteins found in muscle that play role Contractile proteins found in muscle that play role

in actin-myosin interactionin actin-myosin interaction

Complex of 3 protein subunits :Complex of 3 protein subunits :

1. troponin C: calcium binding component1. troponin C: calcium binding component

2. troponin I: inhibitory component2. troponin I: inhibitory component

3. troponin T:tropomyozin_binding component3. troponin T:tropomyozin_binding component

Subunits exist in many isoforms like CKSubunits exist in many isoforms like CK Distribution of these isoforms varies between Distribution of these isoforms varies between

cardiac muscle and slow/fast twitch skeletal cardiac muscle and slow/fast twitch skeletal musclemuscle

Only 2 major isoforms of troponin C are found in Only 2 major isoforms of troponin C are found in human heart and skeletal musclehuman heart and skeletal muscle

Troponin is located in ;Troponin is located in ;

1. myofibril (%94-97)1. myofibril (%94-97)

2. cytoplasm (%3-6)2. cytoplasm (%3-6)

Cardiac troponin I and T have different amino acid Cardiac troponin I and T have different amino acid sequences sequences

Human cTn I has an additional 3I AA residue Human cTn I has an additional 3I AA residue compared to skeletal muscle Tn I (cardiac compared to skeletal muscle Tn I (cardiac specificity)specificity)

11 AA residue gives troponin T unique cardiac 11 AA residue gives troponin T unique cardiac specificity specificity

Early release kinetics of both cTnI and cTnT are Early release kinetics of both cTnI and cTnT are similiar to CK-2 after AMI similiar to CK-2 after AMI

EElevation at 4-8 hr.levation at 4-8 hr.

RRemains elevated at 4-10 days (replaces LD emains elevated at 4-10 days (replaces LD

isoenzyme assay in the detection of patients isoenzyme assay in the detection of patients

presenting late after AMIpresenting late after AMI))

CCardiac specificity of troponin I and T eliminate ardiac specificity of troponin I and T eliminate

the false clinical impression of AMI in patients with the false clinical impression of AMI in patients with

high CK-2 after skeletal muscle injury high CK-2 after skeletal muscle injury

Troponin T (cTnT)Troponin T (cTnT) CClinical sensitivity is similiar to that of CK-2 in the linical sensitivity is similiar to that of CK-2 in the

48 hr. after the onset of pain (%50-65)48 hr. after the onset of pain (%50-65) RRises within a few hrs. after chest pain,peaks by ises within a few hrs. after chest pain,peaks by

day 2 →Like CK-2, cTnT is insufficient for effective day 2 →Like CK-2, cTnT is insufficient for effective early diagnosis early diagnosis

HHowever cTnT remains high for a longer time (up owever cTnT remains high for a longer time (up to 7-10 days) giving high clinical sensitivity (>to 7-10 days) giving high clinical sensitivity (>%90) up to 5-7 days after AMI .%90) up to 5-7 days after AMI .

When AMI patients are grouped separately from When AMI patients are grouped separately from

other cardiovascular pathologies other cardiovascular pathologies Clinical specificity for cTnT Clinical specificity for cTnT %40-60 %40-60 “ “ “ “ “ “ CK-2 CK-2 %75-80 %75-80

When AMI patients are grouped with unstable When AMI patients are grouped with unstable

angina and minor myocardial injury angina and minor myocardial injury specificity specificity

for cTnT improves to >%80for cTnT improves to >%80

Troponin I (cTnI)Troponin I (cTnI) CComparable to CK-2 for diagnostic sensitivity of omparable to CK-2 for diagnostic sensitivity of

AMI in the first 48-72 hr.AMI in the first 48-72 hr.

AAfter 72-96 hr cTnI sensitivity increases fter 72-96 hr cTnI sensitivity increases

HHas serial rise and fall kinetics similiar to CK-2 as serial rise and fall kinetics similiar to CK-2

after AMI during 48-72 hr, remains elevated 3-7 after AMI during 48-72 hr, remains elevated 3-7

days days

In patients with high CK-2 concentrations due to In patients with high CK-2 concentrations due to

acute skeletal muscle injury following marathon acute skeletal muscle injury following marathon

racing, Duchenne’s muscular dystrophy, chronic renal racing, Duchenne’s muscular dystrophy, chronic renal

failure requiring dialysis,failure requiring dialysis, cTncTn I I is NOTis NOT elevated elevated cTncTn I should be measured in patients with I should be measured in patients with falsely falsely

increased CK-2 valuesincreased CK-2 values for the detection of cardiac for the detection of cardiac

injury injury cTncTn I hasI has (+) predictive value (%95) and (-) predictive (+) predictive value (%95) and (-) predictive

value (%100value (%100))

cTnI is successful:cTnI is successful: in ruling out AMI patients with cocaine induced in ruling out AMI patients with cocaine induced

chest painchest pain

in accurately detecting cardiac injury in patients in accurately detecting cardiac injury in patients

with blunt chest traumawith blunt chest trauma

in accurately determining high incidin accurately determining high incideence of nce of

cardiac injury in critically ill patientscardiac injury in critically ill patients

in risk stratification analysis in risk stratification analysis

neither cTnneither cTn I nor cTnI nor cTn T offered advantages over T offered advantages over

myoglobin in the early (< 2 hr) screening for myoglobin in the early (< 2 hr) screening for

AMI, both troponins could identify AMI > 6 hr AMI, both troponins could identify AMI > 6 hr

after presentation.after presentation.

elevation of troponin T or I within 6 hr of elevation of troponin T or I within 6 hr of

symptomssymptoms increased risk of complicationincreased risk of complication

need for intervention need for intervention

increased cTnI in unstable angina predicts a increased cTnI in unstable angina predicts a

poorer clinical outcomepoorer clinical outcome

to determine the effects of reperfusion, cTnT to determine the effects of reperfusion, cTnT

should be measured at the time of trombolytic should be measured at the time of trombolytic

therapy initiation and 90 min. after therapytherapy initiation and 90 min. after therapy

BNP and NT – pro BNP BNP and NT – pro BNP

(Brain natriuretic peptide)(Brain natriuretic peptide)

To diagnose congestive heart failureTo diagnose congestive heart failure To grade the severity of heart failureTo grade the severity of heart failure To differentiate between heart failure and lung diseaseTo differentiate between heart failure and lung disease To monitor the effects of therapy for heart failureTo monitor the effects of therapy for heart failure

NT pro BNP is a marker in the blood for BNP, a hormone NT pro BNP is a marker in the blood for BNP, a hormone

that rises during cardiac stressthat rises during cardiac stress

Homocysteine Homocysteine An amino acid An amino acid Too much homocysteine in the blood is Too much homocysteine in the blood is

related to a higher risk of coronary heart related to a higher risk of coronary heart diseases, stroke and peripheral vascular diseases, stroke and peripheral vascular diseases.diseases.

Has an effect on atherosclerosis.Has an effect on atherosclerosis. High levels of homocysteine are the High levels of homocysteine are the

result of lack of certain B result of lack of certain B Vitms. ,inheritance or dietary excess and Vitms. ,inheritance or dietary excess and have been implicated in vascular wall have been implicated in vascular wall injury.injury.

Testing for plasma homocysteine Testing for plasma homocysteine levels can improve the assessment of levels can improve the assessment of risk, particularly in patients with a risk, particularly in patients with a personal family history of personal family history of cardiovascular disease.cardiovascular disease.

CRPCRP Sensitive marker of acute and chronic Sensitive marker of acute and chronic

inflammation and infection and in such inflammation and infection and in such cases is increased several hundred- fold.cases is increased several hundred- fold.

Useful in predicting the risk for a Useful in predicting the risk for a thrombotic event ( a blood clot causing MI thrombotic event ( a blood clot causing MI ))

Heart patients who have persistant CRP Heart patients who have persistant CRP levels between 4-10 mg/dl with clinical levels between 4-10 mg/dl with clinical evidence of low grade inflammation evidence of low grade inflammation should be considered to be at increased should be considered to be at increased risk for thrombosis. risk for thrombosis.

CRP protein results may be affected by CRP protein results may be affected by the use of the use of

-oral contraceptives-oral contraceptives-NSAID’s-NSAID’s-steroids-steroids-salicylates-salicylates-IUD-IUDHomocysteine levels may be affected byHomocysteine levels may be affected by-smoking -smoking -DM-DM-coffee -coffee