Cardiac Causes of Elevated Troponin Ic and c Tn

Cardiac troponin ic is composed of three proteins, TnC, TnI and TnT. When cardiomyocytes are damaged by any mechanism, troponin is released into the blood, manifesting as elevated cTnI and cTnT.

Compared with standard cTn, high-sensitivity cTn (hs-cTn) can detect cTn far below the 99th percentile (0.04 ng/mL) of the normal reference population. The increased sensitivity has led to a significant increase in the number of patients for whom cTn can be detected, creating a challenge for differential diagnosis.

It is worth noting that although there are many causes of cTn elevation, the degree of cTn elevation in different diseases is not the same, and the combination of clinical manifestations is helpful for differential diagnosis.

In addition to ACS, cardiac causes of elevated troponin cTn:

1. Acute pericarditis of troponin ic

Although troponin ic is absent in the pericardium, troponin ic may be elevated due to the involvement of the epicardium in inflammatory processes. In addition, some myocardial damage may also occur. The pattern of troponin ic release in acute pericarditis is similar to that in ACS.

Acute pericarditis and ACS may coexist, so troponin ic cannot be used in the differential diagnosis between the two. But unlike ACS, troponin ic positivity is not associated with poor prognosis in acute pericarditis.

2. Acute myocarditis of troponin ic

Both acute myocarditis and MI have symptoms of chest pain, segmental wall motion abnormalities, and myocardial necrosis. In the study population with biopsy-proven myocarditis, the troponin ic positive rate is 34%.

The study also found that troponin ic is more sensitive than CK-MB protein and correlated well with heart failure symptoms 1 month after acute myocarditis. The duration of cTn elevation correlates with the severity of inflammation.

3. Troponin ic cardiomyopathy

Takotsubo cardiomyopathy is commonly known as stress cardiomyopathy or ruptured heart syndrome. This cardiomyopathy most commonly affects older women with underlying emotional or physical stress and occurs less frequently in men and younger patients.

The disease is thought to occur concurrently with catecholamine-induced myocardial injury, multivessel epicardial or multivessel spasm, and focal myocardial inflammation. Patients usually suffer from chest pain and/or dyspnea.

ECG can show ST-segment elevation with elevated troponin ic. Troponin ic elevations typically peak within the first 24h but are lower in magnitude compared with ST-segment elevation MI patients.

4. Troponin ic tachycardia

Supraventricular or ventricular tachycardia, atrial fibrillation with high ventricular response, or any other tachycardia may cause ctni troponin elevation without epicardial coronary stenosis by increasing myocardial oxygen demand. Temporary cardiomyocyte damage due to impaired hemodynamics is the mechanism responsible for this phenomenon.