Abbott i-STAT 1 System Manual page 505

The European Society of Cardiology / American College of Cardiology consensus document notes that in
the clinical setting of a reinfarction, CK-MB may be more useful for monitoring for MI than cardiac troponin
I (cTnI) or cardiac troponin T (cTnT) because CK-MB remains increased for only 2-4 days following an MI,
in contrast to up to 5 days for cTnI or 10 days for cTnT.
close relationship between the extent of injury to the myocardium (infarct size) following MI and increased
serum CK-MB mass concentrations.
MB estimated infarct sizing and left ventricular echocardiography.
Other conditions involving skeletal muscle damage like accidents, blunt trauma, severe burns, and extreme
exercise or myopathic disorders such as myocarditis that are not secondary to ischemic coronary artery
disease can also lead to skeletal muscle or myocardial injury and have the potential to cause elevations
in the blood concentrations of CK-MB. These conditions should be considered when interpreting results,
and the CK-MB level should be used in conjunction with clinical symptoms, signs, patient history, and
ECG changes.
1,9
Performance Characteristics
Precision data were collected in multiple sites as follows: Duplicates of each control were tested daily for
a period of 20 days for each of three lots of cartridges, resulting in a total of 120 replicates. The average
statistics are presented below.
Method comparison data were collected using CLSI guideline EP9-A2.
collected in heparinized evacuated tubes and analyzed in duplicate on the i-STAT System. A portion of
the specimen was centrifuged and the separated plasma was analyzed in duplicate on the i-STAT System
and on the comparative method within 1 hour of collection.
Deming regression analysis
comparison table, n is the number of specimens in the first data set, Sxx and Syy refer to estimates of
imprecision based on the duplicates of the comparative and the i-STAT methods, respectively. Sy.x is the
standard error of the estimate, and r is the correlation coefficient.*
Method comparisons may vary from site to site due to differences in sample handling, comparative method
calibration and other site specific variables.
Interference studies were based on CLSI guideline EP7-A.
*The usual warning relating to the use of regression analysis is summarized here as a reminder. For any analyte, "if the data is a narrow range, the
estimate of the regression parameters are relatively imprecise and may be biased. Therefore, predictions made from estimates may be invalid",
correlation coefficient, r, can be used as a guide to assess the adequacy of the comparative method range in overcoming the problem. As a guide, the
range of data can be considered adequate if r>0.975.
Precision Data (ng/mL)
Plasma Control
Rev. Date: 01-Jul-13
Similarly, significant correlations have been observed between CK-
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was performed on the first replicate of each sample. In the method
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Mean
Level 1 5.9
Level 2 25.8
Level 3 90.1
Art: 716675-01L
Clinical studies have also demonstrated a
3,4,5,6,7
8
Venous blood samples were
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SD %CV
0.7 11.9
2.7 10.4
9.0 10.0
The
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CK-MB - 3