Recognising coronary occlusion before troponin returns

A patient with ongoing chest pressure has an ECG concerning for acute coronary occlusion. The first troponin result has not returned. Waiting for it may feel like a cautious step, but a convincing coronary occlusion pattern should activate the reperfusion pathway without delay.

The difficulty is that not every occluded coronary artery produces a textbook ST-elevation myocardial infarction (STEMI) pattern.

Regional ST elevation with reciprocal ST depression provides important evidence of acute coronary pathology, but the absence of classic ST elevation does not exclude an occluded artery. An initial ECG may also be non-diagnostic. Comparing it with previous tracings and repeating it when symptoms evolve can reveal important changes.

The history matters just as much. Patients may describe pressure, tightness or squeezing rather than pain. Breathlessness, nausea, vomiting or discomfort between the shoulder blades may also feature. The severity of symptoms cannot establish or exclude myocardial infarction, and describing symptoms as “atypical” can contribute to missed diagnoses, particularly in women.

Troponin has a specific role in this assessment.

A concentration above the assay-specific, sex-specific 99th percentile identifies myocardial injury. A rise or fall suggests acute injury, while a persistently elevated but stable concentration suggests chronic injury.

To diagnose myocardial infarction, however, there must also be evidence of acute ischaemia.

This distinction prevents an important diagnostic error. A patient with pulmonary embolism may have a rising troponin without evidence of acute myocardial ischaemia. That does not automatically make the diagnosis a secondary myocardial infarction. The latter requires an oxygen supply–demand imbalance accompanied by evidence of ischaemia.

Interpreting troponin also requires attention to the assay and timing. Absolute changes are generally more informative at low concentrations, while relative changes can help when the baseline is substantially elevated. A single low result cannot reliably close the assessment when ischaemic symptoms persist or recur. Serial testing through a validated local pathway remains important.

Even when serial troponins do not demonstrate acute myocardial injury, ischaemic symptoms may represent unstable angina. The decision about admission or further investigation still depends on the clinical picture.

Once acute coronary occlusion is recognised, the challenge shifts from diagnosis to treatment. Anaesthesia for primary percutaneous coronary intervention may require airway management and haemodynamic support, particularly in patients developing cardiogenic shock. Coordination matters, but placing an additional arterial line should not delay reopening the artery when suitable monitoring is already available.

The practical sequence is to assess the symptoms, obtain and interpret the ECG, and act promptly on convincing evidence of coronary occlusion. Troponin helps establish myocardial injury and refine the diagnosis, but a patient with persistent ischaemic symptoms and evolving ECG changes may need reperfusion before the laboratory result arrives.