How is a myocardial infarction classically diagnosed?

A myocardial infarction, commonly referred to as a heart attack, is classically diagnosed through a combination of clinical features, elevated cardiac enzymes, and specific changes on an electrocardiogram (ECG). The most telling indicators are elevated cardiac biomarkers, such as troponins, which indicate damage to heart muscle, along with an ECG that shows ST-segment elevation. This ST-segment elevation is indicative of acute myocardial ischemia, typically associated with a more serious form of heart attack known as ST-elevation myocardial infarction (STEMI).

While chest X-ray findings may show cardiac silhouette or signs of heart failure, they do not provide definitive information about myocardial ischemia. Coronary angiography, although valuable for confirming the presence and extent of coronary artery disease, is not used as a primary diagnostic tool for an acute myocardial infarction. It generally follows laboratory and ECG findings for further evaluation or intervention. Similarly, while physical examination findings can provide clues – such as signs of distress or abnormal heart sounds – they are not definitive for diagnosing a myocardial infarction.

Therefore, the combination of elevated cardiac enzymes and an ECG showing ST-segment elevation is the classic diagnostic approach for myocardial infarction, as it directly indicates myocardial damage and the urgency for treatment