DOCTOR'S VIEW ARCHIVE
BOSTON, MASS - Small advances sometimes lead to big changes in medical care. Two studies reported the New England Journal of Medicine (NEJM, 1997) suggest that such may soon be the case for those suffering from Coronary Artery Disease.
The present means of measuring damage to heart muscle-involves EKG changes & or elevations of enzymes known as CPK-MB. Unfortunately, enzyme changes do not appear until death of heart cells occurs. Thus, in those with a non-diagnostic EKG, serial measurements of cardiac enzymes over several hours are needed to determine if indeed damage to heart cells has occurred. This has lead to the search for a more sensitive diagnostic tool, in the hope of being able to open blocked arteries-before death of heart cells begins.
In several studies of relatively small numbers of patients with acute coronary syndromes, cardiac troponin I and T blood levels measured with new assays have been shown to be very sensitive and specific markers of myocardial (heart)-cell injury. In the October 31, 1996 issue of the New England Journal of Medicine (Volume 335;Issue 18), two large studies of such patients are reported that assess the prognostic value of a single measurement of cardiac troponins in serum at the time of hospital admission.
In the first study-"Cardiac Troponin T Levels for Risk Stratification in Acute Myocardial Ischemia"-855 patients were evaluated in a prospective manner; the findings showed that elevated Troponin T levels were associated with a significantly greater mortality.
In the second study-"Cardiac-Specific Troponin I Levels to Predict the Risk of Mortality in Patients with Acute Coronary Syndromes"-1404 cases with unstable angina were evaluated retrospectively; this showed that the higher the Troponin I levels, the higher the risk of death.
The accompanying Editorial-"Cardiac Troponins
in Acute Coronary Syndromes" confirms that these studies
may soon enable us to more accurately determine which patients
are at increased risk for the serious consequences of decrease
in cardiac blood flow. Initial studies suggest that earlier diagnosis
can lead to improved treatment and decreased mortality. The editors
at MedicineNet feel that if testing for troponins
is supported by further studies, this test may become a standard
part of the evaluation of patients with possible impending heart
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