The case for cardiac troponin T: marker for effective risk stratification of patients with acute cardiac ischemia

Abstract

Availability of markers such as cardiac troponin T (cTnT) has brought new insights into ischemic heart disease (IHD). cTnT is a distinct protein that differs from other markers in biological function, molecular mass, and cytosolic pool. cTnT has been utilized for diagnosis of acute myocardial infarction (AMI) and risk stratification of patients with IHD. For AMI diagnosis, cTnT showed high sensitivity (94-100%) but generally lower specificity (46-99%), possibly because of increases in non-AMI patients with minor myocardial damage. Outcome studies have demonstrated that IHD patients with increased cTnT are at significantly greater risk for cardiac events; revascularization in patients with increased cTnT may improve outcome. Estimated costs for batched ES 300 cTnT results and for a cTnT rapid assay run "on demand" were $17.48 and $21.65, respectively. cTnT currently has no specific common procedure test code; expected reimbursement is $18.32 for the ES 300 and is not established for the rapid assay.

The Troponins

“…Results are obtainable in 85 minutes at an estimated cost of $17.48 per reportable result. 9 A second-generation troponin T enzyme-linked immunosorbent assay has recently been developed. 10 Muller-Bardorff et al 10 were able to improve specificityusingahigh-affinitycardiacspecificantibody,M11.7,andlowerthe discriminating value to 0.1 µg/L with a turnaround time of 45 minutes.…”

“…A positive result is obtained in patients with 0.2 ng/mL or more of cardiac troponin T in their blood, at an estimated cost of $21.65 per reportable result. 4,9 Similarly, a sensitive fluorometric sandwich enzyme immunoassay has been developed to measure cardiac troponin I. 6 This assay uses 2 monoclonal antibodies that recognize 2 different epitopes on the cardiac troponin I molecule.…”

Clinical Utility of Cardiac Troponin I and Cardiac Troponin T Measurements

“…Because cTnI and cTnT do not normally circulate in the blood and are more (for example cTnI 13 times) abundant in the myocardium than CK-MB on a weight basis, the signal-to-noise ratio associated with cardiac troponins is much more favourable for detection of minor amounts of cardiac necrosis missed by other biochemical markers. This ability is very significant because several studies (5,9,24,36,46,48) have indicated that patients with acute cardiac ischemia in whom myocardial infarction was ruled out, but in whom the cTnT value exceeded a defined cutoff, were at increased risk for frank AMI or cardiac death. Although different cutoffs were used in these studies, metaanalysis by Wu and Lane (49) clearly demonstrated that patients with increased cTnT have fourfold increased odds for an adverse event compared with those patients for whom cTnT was negative.…”

Structural and functional modification of the regulatory tropomyosin-troponin protein complex of cardiac myofllaments during heart diseases development

“…Изучение TM из различных объектов позволило разработать структурно-функциональную модель этой молекулы. TM состоит из двух α-спиральных полипептидных цепей, закру ченных друг относительно друга, и имеет вид стержня длиной около 40 [39]. Недостатком его как маркера является наличие белка и в сердечной, и в скелетной мышцах.…”

“…Т:аТ -высокочувствительный маркер поражені: . [ миокарда при остром инфаркте и ишемических поражениях сердца [40]. Показано, что пациенты, страдающие ишемией и имеющие высокий уровень сердечного ТнТ В крови, характеризуются очень плохим щюгнозом.…”