Clinical guidelines from the disciplines of cardiology and laboratory and emergency medicine have all emphasized the importance of cardiac markers in diagnosing or ruling out acute myocardial infarction. The measurement of cardiac troponins is especially useful in the large fraction of patients presenting with acute coronary syndrome (ACS) who have negative 12-lead EKGs. About 30% of patients previously considered to have unstable angina are now given a diagnosis of myocardial infarction without ST-segment elevation based on their cardiac troponin levels. Troponin levels additionally aid in risk stratification.
The development of accelerated protocols for diagnosing ACS in patients with chest pain necessitates the reduction of turnaround time (TAT) for cardiac marker results. Recommendations for the optimum TAT vary from 30 to 60 minutes. With regard to TAT, quantitative point of care (POC) assays that directly assay whole blood provide an attractive alternative to central lab testing. Although the advantages of rapid TAT must be balanced with the need for stringent quality control (QC), many POC analyzers have internal QC systems, and manufacturers provide external controls appropriate to each assay.
Biosite Inc., Response Biomedical Corp., and Roche Diagnostic Systems have FDA approved point of care technology to measure cardiac markers. The indications for use are for rapid quantitative measurement of markers to aid in the diagnosis of myocardial injuries.
Biosite Inc. offers the Triage Cardiac Panel, a fluorescence immunoassay for quantitative determination of CK-MB, myoglobin and troponin I in whole blood and plasma specimens using EDTA as the anticoagulant. To perform the test, a blood sample is added to the sample port of the test device from the Triage Cardiac Panel Kit. The device contains all the reagents for the test. After red blood cells are separated from plasma via filter , the plasma moves into the reaction chamber and reacts with fluorescent-conjugated antibodies to all three markers. After incubation, the sample-reagent mixture flows through the device detection lane where complexes of analyte and conjugates are captured. The level of fluorescence is directly proportional to the concentration of the analyte. The device is read in the Triage MeterPlus, which is a multifunctional reader also utilized for other Triage assays. The test yields simultaneous results for all three markers in approximately 15 minutes. Data can be managed using Triage Census data management software and uploaded quickly to laboratory information systems. The system contains both internal and external quality controls that are user-friendly. The reader is compact and portable, with a self-contained power source.
Response Biomedical Corp. offers the RAMP Cardiac Marker System, with separate test kits for CK-MB, myoglobin and troponin I. It is also a quantitative immunofluorescence assay for EDTA whole blood specimens. To perform the test, a diluted blood sample is added to the sample well of the test cartridge, the red blood cells are retained, and the plasma migrates. Fluorescent-dyed latex particles coated with antigen specific antibodies bind to antigen in the sample. Antigen-bound particles are captured in the detection zone and excess particles are captured at the internal control zone by anti-immunoglobins. The fluorescence of the detection and internal control zones is measured by the RAMP Clinical Reader, which is a multifunctional reader utilized for the RAMP platform technology. The ratio of the values is calculated and the analyte is quantified by interpolation from a lot-specific standard curve supplied in the test kit. The tests for CK-MB and Troponin I yield results in 10 and 12 minutes respectively. Data can be uploaded quickly to laboratory information systems. The reader is compact and portable, with a self-contained p ower source.
Roche Diagnostic Systems offers The Cardiac Reader System with separate test strips for for troponin T and myoglobin. It is a quantitative gold-labeled immunochemistry assay for heparinized whole blood specimens. The strips are read in the Cardiac Reader analyzer, which measures the intensity of the signal and control line of each test strip. There is a calibration curve for each test strip lot contained in a code chip, which is utilized by the reader for conversion to a quantitative result. The tests for myoglobin and troponin T yield results in 8 and 12 minutes respectively. Data can be uploaded to laboratory information systems. The system requires an optical quality control and quantitative marker control solutions. The reader is compact and portable, with a self-contained power source.
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