Troponin tests are used, together with an , in people with chest pain to see if they have had a heart attack, have unstable angina or have a problem outside the heart. In a heart attack, a blood clot stops the normal flow of blood and oxygen to the muscle. Without oxygen, the heart muscle cells die and release troponin into the bloodstream. The more extensive the damage is, the greater the release and the higher the blood concentrations become. Concentrations can increase within two or three hours and may remain high for 10 to 14 days. The rise or fall in troponin level is important to differentiate any acute cardiac events such as heart attack from chronic elevations not due to a heart attack.
Normally, troponin levels are very low; even a slight rise indicates some damage to the heart (unstable angina or a heart attack). When a patient has a large increase in troponin concentration, then it is highly likely that they have had a heart attack or some other form of heart damage. If a patient with chest pain and known stable angina has a normal and stable troponin result, it is likely that their heart has not been damaged.
Increased troponin concentrations should not be used by themselves to diagnose or rule out a heart attack. A physical examination, clinical history and electrocardiogram (ECG) or imaging investigations are also essential. The internationally agreed definition of heart attack requires evidence of a significant increase in troponin concentration with time, together with evidence of a sudden reduction of heart muscle blood supply (ischaemia) for example the characteristic symptoms of the acute coronary syndrome (ACS), new ECG changes or new imaging changes.
Without evidence of ischaemia, possible causes of rising troponin values include myocarditis (inflammation of the heart muscle), acute heart failure, an arrhythmia (abnormal heart rhythm) or pulmonary embolism (blood clot lodged in the lung). Elevated but unchanging values may be seen in chronic heart failure, high blood pressure (hypertension), severe infections, kidney disease and some chronic inflammatory conditions of muscle.