Clinical laboratory practice recommendations for high-sensitivity cardiac troponin testing

The role of cardiac troponins (cTn) have become increasingly important in diagnosing myocardial infarction (MI), especially in patients without electrocardiogram abnormalities (1)

The role of cardiovascular magnetic resonance imaging and computed tomography angiography in suspected non-ST-elevation myocardial infarction patients:Design and rationale of the CARdiovascular Magnetic rEsoNance imaging and computed Tomography Angiography (CARMENTA) trial

BackgroundAlthough high-sensitivity cardiac troponin (hs-cTn) substantially improves the early detection of myocardial injury, it lacks specificity for acute myocardial infarction (MI). In suspected non–ST-elevation MI, invasive coronary angiography (ICA) remains necessary to distinguish between acute MI and noncoronary myocardial disease (eg, myocarditis), unnecessarily subjecting the latter to ICA and associated complications. This trial investigates whether implementing cardiovascular magnetic resonance (CMR) or computed tomography angiography (CTA) early in the diagnostic process may help to differentiate between coronary and noncoronary myocardial disease, thereby preventing unnecessary ICA.Study DesignIn this prospective, single-center, randomized controlled clinical trial, 321 consecutive patients with acute chest pain, elevated hs-cTnT, and nondiagnostic electrocardiogram are randomized to 1 of 3 strategies: (1) CMR, or (2) CTA early in the diagnostic process, or (3) routine clinical management. In the 2 investigational arms of the study, results of CMR or CTA will guide further clinical management. It is expected that noncoronary myocardial disease is detected more frequently after early noninvasive imaging as compared with routine clinical management, and unnecessary ICA will be prevented. The primary end point is the total number of patients undergoing ICA during initial admission. Secondary end points are 30-day and 1-year clinical outcome (major adverse cardiac events and major procedure-related complications), time to final diagnosis, quality of life, and cost-effectiveness.ConclusionThe CARMENTA trial investigates whether implementing CTA or CMR early in the diagnostic process in suspected non–ST-elevation MI based on elevated hs-cTnT can prevent unnecessary ICA as compared with routine clinical management, with no detrimental effect on clinical outcome

Circulating forms of cardiac troponin:a review with implications for clinical practice

Cardiac troponin I (cTnI) and T (cTnT) became the gold-standard biomarkers for diagnosing myocardial infarction (MI) due to their cardiac-specific amino acid sequence. Currently, both cTnI and cTnT are considered equivalent as their diagnostic performance is comparable. The introduction of highsensitivity (hs-)cTn immunoassays allowed a more accurate assessment of cTn concentrations in the lower analytical range resulting in a higher number of non-ST-elevated MI (NSTEMI) diagnoses. However, the increased sensitivity also resulted in hs-cTn elevations in other (non-)cardiac pathologies and even in physiological conditions, such as vigorous exercise. To differentiate acute MI from these other conditions it was suggested that the circulating form of cTn might serve useful, since research illustrated different circulating cTnI and cTnT forms in the blood circulation. Studies in acute MI patients have shown that cTnI appears to be mostly present in a binary (cTnI-C) complex. Also, a variety of different cTnI fragments was observed post-MI, but no time-dependent cTnI degradation effect was found dependent on symptom onset. For cTnT, mainly larger forms were found in MI, while in other conditions with elevated hs-cTnT concentrations, the smallest fragments were almost exclusively present. Based on this preliminary data it might be clinically relevant to develop a novel hs-cTnT immunoassay which solely targets specific cTnT forms observed in acute MI that could help to further increase the specificity of hs-cTnT immunoassay for the diagnosis of acute MI. The present traditional literature review provides an overview of research on circulating cTn forms performed thus far