High-sensitivity cardiac troponin assays detect very small amounts of myocardial injury. That sensitivity lets us rule out infarction faster than ever, but it also means more patients have a detectable troponin for reasons other than a blocked coronary artery.
Injury versus infarction
Myocardial injury is defined as a troponin above the 99th percentile upper reference limit. Acute myocardial infarction requires a rise and/or fall in troponin plus clinical evidence of ischaemia — symptoms, new ECG changes, imaging evidence or an angiographic thrombus.
Common non-coronary causes of a raised troponin:
- Sepsis and critical illness
- Pulmonary embolism
- Heart failure and myocarditis
- Chronic kidney disease
- Tachyarrhythmias
Rapid rule-out pathways
Validated 0/1-hour and 0/2-hour algorithms combine a baseline value with the change over a short interval. A very low baseline troponin, in a patient whose pain started more than three hours earlier, can safely rule out infarction in many cases. Each algorithm is specific to the assay used, so local pathways must match the laboratory platform.
“The trend tells you more than any single number.”
Practical points
Always interpret troponin alongside the ECG and the history. A stable, chronically raised value in kidney disease behaves very differently from a sharp rise. When the result does not fit the clinical picture, repeat it and look for an alternative diagnosis.
This article is for education only and does not replace clinical judgement or local guidelines.
