Interpretation of cardiac troponin levels regarding the fourth universal definition of myocardial infarction published in 2018

Abstract

Cardiac troponin (cTn) is a laboratory test routinely used in patients with suspected acute coronary syndrome (ACS). Unfortunately, wide variety of laboratory assays and different cut-off values regarding gender may result in difficulties with diagnosis and delay the treatment. Troponin I and less specific troponin T are used to diagnose ACS. Dynamic changes in cTn concentration are required to confirm the diagnosis of myocardial infarction (MI). The fourth universal definition of myocardial infarction defines five major types of MI — atherosclerotic plaque disruption, imbalance between myocardial oxygen supply and demand unrelated to acute coronary atherothrombosis, cardiac death with symptoms suggestive of myocardial ischaemia and new ischaemic electrocardiographic changes, MI connected with percutaneous coronary intervention or coronary bypass grafting. Considering this definition, increased cTn concentrations are not always related to abnormal findings in coronary angiography and can be associated with many conditions. Increased high sensitivity cTn values in healthy individuals can be induced by intense physical activity, which is confirmed by studies performed in marathoners. While elevated cTn levels are observed in 20–60% of patients with acute ischemic stroke and are associated with an increased long-term mortality, acute MI is diagnosed only in 3,5% of patients. Elevated cTn levels often accompany chronic kidney disease, however changes in serial testing are obligatory for acute MI diagnosis. Deterioration of kidney function is more connected with elevated TnT rather than TnI levels. Regardless of the reason, increased cTn concentration is a negative predictive factor. Patients with elevated cTn levels need further diagnosis, risk stratification and a long-term follow-up.