BLUEGRASS COMMUNITY HOSPITAL

POLICY

/ ORIGINATION DATE: 03/10/04
DEPARTMENT OF ORIGIN:
Laboratory, Med Exec Committee / REVISE DATE:
AFFECTED AREA:
Laboratory, Emergency Department, Med/Surg, Surgery, and other hospital areas / REVIEWED DATE:
SUBJECT: Cardiac Markers for Chest
Pain Evaluation / APPROVED BY:

POLICY: to set recommendations for Cardiac Markers in the triage of patients presenting with chest pain in the Emergency Department or other areas of the hospital in order to improve and aid in their efficiency of evaluation and diagnosis. Cardiac Markers TAT (turn-around time) must be < 1 hour.

PURPOSE: Proper evaluation of patients with acute chest pain is critical for effective diagnosis and treatment. Resources, treatment, and cost must be managed to provide the earliest recognition of a cardiac ischemic event and proper placement in the risk spectrum for acute coronary syndrome (ACS). Myocardial necrosis results in the appearance of blood biochemical proteins released into circulation by the damaged myocytes: myoglobin, cardiac troponins T and I, creatine kinase (CK), CK-MB, lactate dehydrogenase (LD), and others. Myocardial infarction can be diagnosed when specific biochemical cardiac markers such as Troponins, CK-MB, and Myoglobin are detected and increased above upper limits of normal (ULN) for acute ischemia. These cardiac markers indicate damage but not its mechanism. Therefore, an elevated marker in the absence of clinical evidence of ischemia is indicative of other causes of cardiac damage, such as myocarditis.

Common cause of chest pain

Cardiac Pulmonary Others

Ischemic syndromes Bronchitis Vascular

Stable angina Bronchospasm Aortic dissection

Unstable angina Empyema Pulmonary embolism

Variant angina Pleural effusion Pulmonary hypertension

AMI Pleuritis Gastrointestinal

Valvular disease Pneumonia Esophageal spasm

Mitral valve prolapse Pneumothorax Gastroesophageal reflux Aortic stenosis Pulmonary edema Mallory-Weiss tear

Subaortic stenosis Aortic dissection Esophagitis/gastritis

Cardiomyopathy Pulmonary embolism Gastric/duodenal ulcer

Pericarditis Pulmonary hypertension Biliary colic

Musculoskeletal

Costochondritis

Muscle strain/spasm

Cervical radiculopathy

Neurologic

Herpes Zoster

aTaken from Green GB, Green SF. Markers of myocardial injury in the evaluation of the emergency department patient with chest pain. In: Wu et al. ed., Cardiac Markers, Totowa NJ: Humana Press, 1998, p. 77.

CARDIAC (BIOCHEMICAL) MARKERS

TROPONIN (cTnI or LTnI): is the preferred cardiac marker for myocardial damage, risk stratification, and peri- and post-cardiac surgery. Low detectable levels in UA patients with non-ST segment elevation are indicative of increased risk for short-term adverse events: death, AMI (acute myocardial infarction) or urgent coronary events requiring urgent revascularization. It has a greater sensitivity than CK-MB and can detect MI (myocardial infarction) up to 2 weeks after onset and reperfusion. It has low sensitivity in very early phase of MI (< 6 hours after symptom onset) and requires repeat (serial) testing at 8 – 12 hours if initial testing is negative. Troponin has limited ability to detect late minor reinfarction.

AMI Cutoff: 0.6 – 1.5 ng/ml

Risk Stratification: 0.1 – 0.5 ng/ml

Health normal individuals: 0.0 – 0.07 ng/ml

MYOGLOBIN (MYO): is useful in early detection of MI, re-infarction, and reperfusion and monitoring successful reperfusion therapy. In ruling out MI, myoglogin should not be used in cases of trauma or muscular skeletal disease. It may appear in the blood at abnormal levels within 1 – 3 hours after onset of myocardial ischemia. Myoglobin levels that double within 1 – 2 hours after chest pain presentation are highly specific indicators for AMI. It is statistically more sensitive than CK-MB and has an excellent negative predictive value for ruling out AMI in patients with typical or atypical symptoms. Its rapid return to normal values limits its sensitivity for later presentation.

Healthy normal individuals: 10 – 92 ng/ml

AMI cutoff: 2x baseline within 1 –2 hours of presentation

Negative Predictive Value of Selected Cardiac Markers:


CK-MB (MB): used as an aid in diagnosis of AMI and detecting re-infarction. CK-MB is not specific to the myocardium and can be present due to non-cardiac events such as skeletal muscle injury or disease including surgery. It also has low sensitivity during early MI with elevation not seen until 6 – 8 hours after symptom onset and for minor myocardial damage. Troponin has basically replaced CK-MB for MI and cell damage.

AMI cutoff: > 5.0 ng/ml

Healthy normal individuals: 0 – 3.6 ng/ml

Kinetics of Cardiac Marker Release in Blood

Plot of the appearance of cardiac markers in blood vs time after onset of symptoms. Peak A, early release of myoglobin after AMI; Peak B, cardiac troponin after AMI; Peak C, CK-MB after AMI; Peak D, cardiac troponin after unstable angina. Data are plotted on a relative scale, where 1.0 is set at the AMI cutoff concentration.

Kinetic Characteristics
Beginning / Peak / Duration
Myoglobin / 0.5 – 2 hours / 5 – 12 hours / 12 – 14 hours
Troponin I / 4 – 8 hours / 12 – 14 hours / 7 – 14 hours
CK-MB / 3 – 8 hours / 10 – 18 hours / 24 – 36 hours

Recommendation I: Initial Evaluation and Management

  1. Patient presentation in ED or other hospital area obtain:

a.  history

b.  physical examination

c.  12 – lead ECG (within 10 minutes of presentation if possible)

d. 




cardiac markers (myoglobin and troponin I with TAT < 1 hour)


























  1. Cardiac Marker Collection Recommendations: Myoglobin and Troponin should be repeated at 0, 3, 6, and 12 hours to rule – out possible AMI if the levels for Myoglobin are < 0.6 ng/ml and for Troponin < 0.1 ng/ml or > 0.1 ng/ml but < 0.6 ng/ml. At 12 hours, if cardiac marker results are exhibiting a negative response, other clinical conditions such as unstable angina should be investigated for cause of chest pain.

Time (Hours) / 0 hrs (onset) / 3 hrs / 6 hrs / 12 hrs
Myoglobin / Ö (< 0.6) / Ö (< 0.6) / Ö (< 0.6) / Ö (< 0.6)
Troponin / Ö (< 0.1) / Ö (< 0.1) / Ö (< 0.1) / Ö (< 0.1)

Definition of MI Criteria for acute, evolving or recent MI:

Typical rise and gradual fall (troponin) or more rapid rise and fall (myoglobin) of biochemical markers for myocardial necrosis with at least one of the following:

·  Ischemic symptoms

·  Devolopment of pathologic Q waves on ECG

·  ECG changes indicative of ischemia (ST ­ or ST ¯)

·  Coronary artery intervention ( e.g. coronary angioplasty)

·  Pathologic findings of an acute MI

Thygesen K, et al, JACC 2000, 36:959-969. Note: Joint ESC/ACC Committee.

References:

Robert H. Christenson, PhD, DABCC, FACB; James de Lemos, MD. (2003). Troponin, the Natriuretic Peptides and Other Biochemical Markers: Understanding Heart Disease, CAP’03, Ed. Course: CP104, pg 1-202, 09/13/03.

Thygesen K, et al, JACC 2000, 36:959-969. Note: Joint ESC/ACC Committee.

Biosite Diagnostics (2000). Cardiac Teleconference, Biosite Diagnostics, Inc., April 25, 2000.

Bayer Diagnostics (

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