What are the symptomatic differences between ST-Elevation Myocardial Infarction (STEMI) versus Non-ST-Elevation Myocardial Infarction (NSTEMI) versus Unstable Angina?

From the Guidelines

The primary difference in symptoms between STEMI, NSTEMI, and unstable angina lies in the severity and duration of chest pain, with STEMI typically presenting with more severe and prolonged pain, while NSTEMI and unstable angina have less severe and more intermittent pain, as noted in the 2020 ESC guidelines for the management of acute coronary syndromes 1.

Symptomatic Differences

• STEMI: typically presents with intense, crushing chest pain that may radiate to the arms, neck, or jaw, and is usually accompanied by other symptoms such as shortness of breath, nausea, and vomiting.
• NSTEMI: may have similar symptoms, but the chest pain is often less severe and may be more intermittent.
• Unstable Angina: typically presents with new-onset or worsening angina that occurs at rest or with minimal exertion, but without the same level of severity as STEMI, as described in the ACC/AHA 2007 guidelines for the management of patients with unstable angina/non ST-elevation myocardial infarction 1.

Diagnostic Considerations

The distinction in symptoms is largely due to the extent of coronary artery occlusion, with STEMI resulting from a complete occlusion, NSTEMI from a partial occlusion, and unstable angina from a transient or incomplete occlusion, as discussed in the National Academy of Clinical Biochemistry laboratory medicine practice guidelines 1.

Clinical Presentations

The three principal presentations of unstable angina are:

• Rest angina: angina occurring at rest and prolonged, usually greater than 20 min.
• New-onset angina: new-onset angina of at least CCS class III severity.
• Increasing angina: previously diagnosed angina that has become distinctly more frequent, longer in duration, or lower in threshold, as outlined in the ACC/AHA 2007 guidelines 1. The symptoms of NSTEMI are distinguished from unstable angina by the detection of cardiac markers indicative of myocardial necrosis in NSTEMI and the absence of abnormal elevation of such biomarkers in patients with unstable angina, as noted in the ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction 1.

From the Research

Symptomatic Differences

The symptomatic differences between ST-Elevation Myocardial Infarction (STEMI), Non-ST-Elevation Myocardial Infarction (NSTEMI), and Unstable Angina are as follows:

• STEMI typically presents with severe, crushing chest pain that may radiate to the arms, back, or jaw, and is often accompanied by nausea, dyspnea, or diaphoresis 2.
• NSTEMI may present with similar symptoms to STEMI, but the ECG changes are not as pronounced, and cardiac troponin levels are elevated 2, 3.
• Unstable Angina (UA) is characterized by chest discomfort or angina that occurs at rest, is anginal in character, and may radiate to the arms, back, or jaw, but without elevated cardiac troponin levels 2, 3.

Clinical Presentation

The clinical presentation of these conditions can be similar, making diagnosis challenging:

• All three conditions can present with chest pain or discomfort, but the characteristics and severity can vary 2, 4.
• UA and NSTEMI can have similar pathophysiology, but with increasing severity 5.
• STEMI typically has more pronounced ECG changes and higher cardiac troponin levels compared to NSTEMI and UA 2, 3.

Prognosis and Outcomes

The prognosis and outcomes for these conditions differ:

• UA has a lower mortality rate compared to NSTEMI and STEMI, but similar or worse health status outcomes and cardiac rehospitalization rates 3, 4.
• NSTEMI has a higher mortality rate and worse prognosis compared to UA, but similar health status outcomes and cardiac rehospitalization rates 6, 3.
• STEMI has the highest mortality rate and worst prognosis, but UA patients have similar or worse health status outcomes and cardiac rehospitalization rates despite better survival rates 4.

Key Features

Key features that distinguish these conditions include:

• ECG changes: STEMI typically has ST-segment elevation, while NSTEMI has ST-segment depression or T-wave inversion, and UA has no significant ECG changes 2.
• Cardiac troponin levels: Elevated in NSTEMI and STEMI, but not in UA 2, 3.
• Clinical presentation: Severity and characteristics of chest pain or discomfort, presence of nausea, dyspnea, or diaphoresis 2, 4.