What markers should be ordered for a patient presenting with angina pectoris?

Markers to Order for Angina Pectoris

Cardiac-specific troponin (troponin T or I) is the preferred and essential biomarker that must be measured in all patients presenting with angina pectoris, with repeat measurement at 8-12 hours if initial values are negative within 6 hours of symptom onset. 1

Essential Cardiac Biomarkers

Primary Marker - Cardiac Troponin (Class I Recommendation)

• Cardiac troponin T (cTnT) or troponin I (cTnI) should be measured on admission in all patients with chest discomfort consistent with acute coronary syndrome 1
• Troponin is the preferred marker due to superior sensitivity and specificity compared to CK-MB, and can detect myocardial damage in approximately one-third of patients with unstable angina who have normal CK-MB 1
• Repeat troponin measurement is mandatory at 8-12 hours after symptom onset if initial biomarkers drawn within 6 hours are negative 1
• Troponin remains elevated for up to 2 weeks, allowing detection of recent myocardial infarction 1

Secondary Marker - CK-MB

• CK-MB mass remains an acceptable alternative diagnostic test when troponin is unavailable 1
• CK-MB has lower sensitivity and specificity than troponins but is familiar to most clinicians 1
• Elevated CK-MB (e.g., >99th percentile) indicates intermediate to high risk 1

Risk Stratification Based on Cardiac Markers

High-Risk Features

• Elevated cardiac troponin >0.1 ng/mL indicates high risk for death or nonfatal MI 1
• These patients require hospital admission and aggressive management 1

Intermediate-Risk Features

• Slightly elevated troponin (0.01-0.1 ng/mL) indicates intermediate risk 1
• Warrants close observation and serial marker measurements 1

Low-Risk Features

• Normal cardiac markers suggest lower immediate risk but do not exclude unstable angina 1
• Serial measurements remain necessary to exclude evolving myocardial injury 1

Optional Early Markers (Class IIb Recommendations)

For Patients Presenting Within 6 Hours of Symptom Onset

• Myoglobin in conjunction with troponin may be considered for early detection 1
• Myoglobin has high early sensitivity (22-53% at 0-2 hours) but very low specificity, particularly with skeletal muscle injury 1
• 2-hour delta CK-MB mass in conjunction with 2-hour delta troponin may be considered 1
• Myoglobin with CK-MB or troponin measured at baseline and 90 minutes may be considered 1

Critical caveat: Myoglobin should never be used alone to exclude MI due to declining sensitivity after 6 hours and lack of cardiac specificity 1

Additional Risk Assessment Marker

• B-type natriuretic peptide (BNP) or NT-pro-BNP may be considered to supplement global risk assessment 1
• This provides prognostic information beyond traditional cardiac injury markers 1

Timing of Biomarker Measurements

Initial Assessment

• 12-lead ECG within 10 minutes of emergency department arrival 1
• Immediate cardiac biomarker measurement at presentation 1

Serial Measurements

• Repeat at 8-12 hours if initial markers negative and symptoms began within 6 hours 1
• Exact timing should account for uncertainties in symptom onset, assay sensitivity/precision, and marker release kinetics 1
• Serial ECGs at 15-30 minute intervals if initial ECG non-diagnostic but high clinical suspicion persists 1

After Recurrent Chest Pain

• Repeat troponin and/or CK-MB measurements after any further episodes of severe chest pain 1

Comparative Marker Performance

Troponin demonstrates superior diagnostic accuracy: In a study of 109 PCI patients, cTnI detected myocardial damage in 58 patients versus 38 for cTnT and only 28 for CK-MB, with all three markers providing equally reliable prognostic information for major adverse cardiac events 2

The sensitivity of markers increases with time from symptom onset: at 8-10 hours, CK-MB reaches 90-98%, troponin T 87-95%, and troponin I 92-93% sensitivity 1