Angina vs Myocardial Infarction: Key Differences and Diagnostic Approaches

Accurately distinguishing between angina and myocardial infarction (MI) requires professional medical evaluation. These two cardiac conditions share similar symptoms but differ significantly in severity and long-term implications. Below are three primary methods healthcare providers use to differentiate between them:

1. Clinical History and Symptom Presentation

Both angina and myocardial infarction can cause chest discomfort in similar locations, often centered or on the left side of the chest. However, MI typically presents with more intense and prolonged pain. While angina is often triggered by physical exertion or emotional stress and relieved by rest or nitroglycerin, myocardial infarction pain may occur at rest, last for several hours, and show poor or no response to nitroglycerin. Some patients may experience symptoms for up to 1–2 days without relief.

2. Physical Examination Findings

In patients with angina, vital signs usually remain stable. Blood pressure may be elevated due to stress but typically does not drop significantly. There is no fever, and respiratory rate remains normal. In contrast, patients experiencing a heart attack may show signs of hemodynamic instability, including hypotension that can progress to shock. Increased respiratory rate and mild fever are also commonly observed in MI patients, especially a day or two after the event.

3. Diagnostic Testing and Laboratory Evaluation

Electrocardiogram (ECG) plays a crucial role in differentiating angina from MI. In myocardial infarction, characteristic ECG changes such as ST-segment elevation or depression and the development of pathological Q waves may be observed. These changes often evolve over time, making serial ECGs essential for accurate diagnosis.

Cardiac Biomarkers and Advanced Imaging

Elevated levels of cardiac biomarkers such as troponin and creatine kinase-MB (CK-MB) are strong indicators of myocardial damage. These markers typically rise and fall in a predictable pattern, helping clinicians confirm MI. For atypical presentations, repeated biomarker testing and ECG monitoring are necessary. In some cases, additional diagnostic tools such as echocardiography, cardiac CT, and coronary angiography are required to confirm the diagnosis and assess the extent of coronary artery disease.