Progressive Care Nursing Certification (PCCN) Practice Exam

What differentiates an NSTEMI from unstable angina?

1. Location of chest pain

2. Elevated cardiac biomarkers

3. ECG changes

4. History of myocardial ischemia

The correct answer is: Elevated cardiac biomarkers

The key differentiator between NSTEMI (non-ST elevation myocardial infarction) and unstable angina lies in the presence of elevated cardiac biomarkers. In NSTEMI, there is actual myocardial injury occurring, which leads to the release of cardiac enzymes such as troponins and creatine kinase-MB (CK-MB) into the bloodstream. These biomarkers indicate that a portion of the heart muscle has been damaged. In contrast, unstable angina does not result in the release of these biomarkers, as there is no significant myocardial necrosis; rather, it reflects a reduction in blood flow to the myocardium that is not sufficient to cause lasting damage. As a result, while patients may experience similar symptoms, such as chest pain or discomfort, and possibly similar ECG changes, the presence of elevated cardiac biomarkers is crucial for distinguishing NSTEMI from unstable angina. Other factors such as the location of chest pain, ECG changes, and the patient’s history of myocardial ischemia can be present in both conditions but do not provide definitive differentiation since they are not unique to NSTEMI alone. Thus, the elevation of cardiac biomarkers is the most reliable and direct measure in clinical practice to distinguish NSTEMI from unstable angina.