10% CV concentration for the fourth generation Roche cardiac troponin T assay derived from Internal Quality Control data

Abstract BACKGROUND The release kinetics of cardiac troponin T measured with conventional vs high-sensitivity cardiac troponin T (hs-cTnT) assays in patients with acute myocardial infarction (AMI) is difficult to establish. METHODS We analyzed the release kinetics of cTnT measured by fourth generation and high-sensitivity assays, creatine kinase-MB (CK-MB), and myoglobin in patients with hypertrophic obstructive cardiomyopathy undergoing transcoronary ablation of septal hypertrophy (TASH), a model of AMI. Consecutive patients (n = 21) undergoing TASH were included. Serum and EDTA-plasma samples were collected before and at 15, 30, 45, 60, 75, 90, and 105 min, and 2, 4, 8, and 24 h after TASH. RESULTS cTnT concentrations measured by the hs assay were significantly increased at 15 min [21.4 ng/L, interquartile range (IQR) 13.3–39.7 ng/L vs 11.3 ng/L, IQR 6.0–18.8 ng/L at baseline; P = 0.031]. In comparison, cTnT concentrations measured by the conventional fourth generation assay increased significantly at 60 min (30.0 ng/L, IQR 20.0–30.0 ng/L vs <10.0 ng/L, IQR <10.0–10.0 ng/L; P < 0.01), CK-MB at 90 min (8.4 μg/L, IQR 6.9–14.4 μg/L vs 0.9 μg/L, IQR 0.4–1.1 μg/L; P < 0.01), and myoglobin at 30 min (188.0 μg/L, IQR 154.0–233.0 μg/L vs 38.0 μg/L, IQR 28.0–56.0; P < 0.01). CONCLUSIONS cTnT concentrations measured by the hs assay were significantly increased after TASH at all of the time points, with a doubling at 15 min after induction of AMI, confirming earlier evidence of myocardial injury compared to the fourth generation cTnT assay and CK-MB and myoglobin.

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Highly Sensitive Cardiac Troponin T Values Remain Constant after Brief Exercise- or Pharmacologic-Induced Reversible Myocardial Ischemia

Clinical Chemistry ◽

10.1373/clinchem.2007.097865 ◽

2008 ◽

Vol 54 (7) ◽

pp. 1234-1238 ◽

Cited By ~ 67

Author(s):

Kerstin Kurz ◽

Evangelos Giannitsis ◽

Joerg Zehelein ◽

Hugo A Katus

Keyword(s):

Myocardial Ischemia ◽

Cardiac Troponin ◽

Troponin T ◽

Stress Test ◽

Photon Emission ◽

Fourth Generation ◽

Emission Computed Tomography ◽

Cardiac Troponin T ◽

Median Baseline ◽

Nuclear Stress Testing

Abstract Background: Using a new precommercial high-sensitivity cardiac troponin T (hsTnT) assay, we evaluated whether hsTnT increases after reversible myocardial ischemia. Methods: In 195 patients undergoing nuclear stress testing (ST) using single-photon emission computed tomography (SPECT) for suspected ischemic heart disease, we measured hsTnT before and 18 min, 4 h, and 24 h after the stress test. Thirty patients were excluded before ST because of cardiac troponin T (cTnT) >30 ng/L (0.03 μg/L) as measured by the fourth-generation commercial test. Another 65 patients were excluded because of a combination of fixed and reversible perfusion defects (PDs) after SPECT. Results: We studied 18 patients with reversible PDs, 41 patients with fixed PDs, and 41 patients without any PDs. Of these 100 patients, 61 received dynamic ST and 39 pharmacological ST. Median baseline hsTnT concentrations (25th, 75th percentile) were comparable in patients with reversible, fixed, and no PDs [5.57 (2.47, 12.60), 8.01 (4.55, 12.44), and 6.90 (4.63, 10.59) ng/L, respectively]. After ST, median hsTnT concentrations did not change in the reversible, fixed, or no PD groups from baseline to 18 min [−0.41 (−0.81, 0.01), 0.01 (−0.75, 0.79), and 0.36 (−0.42, 1.01) ng/L] or from baseline to 4 h [−0.56 (−1.82, 0.74), 0.24 (−0.60, 1.45), and 0.23 (−0.99, 1.15) ng/L]. Median baseline hsTnT concentrations tended to be higher in patients undergoing pharmacological vs dynamic ST; however, there were no significant increases in hsTnT concentrations after either type of ST. Conclusions: Elevation of cTnT is rather a consequence of irreversible myocyte death than reversible myocardial ischemia after exercise or pharmacologic myocardial ischemia.

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