Part 8 of IVD Hall of Fame
« Pre- and Postnatal CF Screening
Myocardial Infarction (MI) panels are used when an acute myocardial infarction or heart attack is suspected. These panels test enzymes or proteins that are linked with injury of the heart muscle such as creatine kinase-MB, troponin I, troponin T and myoglobin. Low levels of these enzymes and proteins are normally found in blood, but if the heart muscle is injured, such as from a heart attack, their levels in the bloodstream rise.
Before MI panels were available, physicians ordered each individual assay on the panel separately. As a result of MI panels, physicians are able to obtain relevant information with one test to aid in the diagnosis of myocardial infarction.
The biomarkers on MI panels are cleared by FDA as individual assays. The first assay for myoglobin was cleared in 1978, creatine kinase in 1977 and troponin in 1994.
In 2007, the National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines and the Joint ESC/ACCF/AHA/WHF Task Force Guidelines recommended the use of cardiac troponin as a biomarker for the diagnosis of myocardial infarction (MI) when used in conjunction with clinical evidence of myocardial ischemia. These recommendations solidified troponin’s importance in MI diagnosis and triage; at the same time, they formalized an adjustment in the clinical cutoffs and changed the way troponin results were interpreted and used.
In 2010, FDA issued a letter to Troponin manufacturers. The letter stated that troponin assays currently available and marketed in the United States obtained 510(k) clearance prior to the 2007 recommendations, and the clinical sensitivities, specificities, and predictive values of these tests were determined using outdated clinical cutoffs and diagnostic criteria. In addition, the letter stated that some cleared assays may not have adequate analytical performance characteristics to support the current manner in which troponin tests are used (e.g., may not be able to reliably detect low enough concentrations of troponin).
FDA asked Troponin manufacturers to provide additional information to ensure that the most current clinical cutoffs and diagnostic criteria were used for these tests. In addition, a large variation in cardiac troponin I concentration, in terms of absolute value, could be observed for a given patient specimen with different analytic methods. A new Standard Reference Material for Human Cardiac Troponin Complex (SRM 2921) was introduced by the National Institute of Standards and Technology (NIST) to aid in the future standardization of troponin assays.
MI panels changed how patients are managed, since relevant markers for MI are grouped onto one panel. Because each biomarker rises and remains elevated at different times following a cardiac event, the panel provides more complete clinical information than each test individually. The result is better information to the physician in the critical moments after a cardiac event.