CORRESPONDENCE: LETTER TO THE EDITOR
Biomarkers in Acute Cardiac Disease
Nagapradeep Nagajothi, MD* and
Atul Trivedi, MD
* Mount Sinai Hospital, Division of Cardiology, California Ave at 15th Street, Chicago, Illinois 60608 (Email: nagapradeepnagajothi{at}yahoo.com).
In their state-of-the-art paper on biomarkers in acute cardiac disease (1), Dr. Jaffe and colleagues list creatine kinase-MB (CK-MB) as a "potentially outdated marker." However, CK-MB has a specific utility in the diagnosis of reinfarction (2), and it cannot be replaced by the cardiac troponins for this purpose. By following up the time course of rise and fall of CK-MB, an interruption in the progressive decline in the level of the biomarker (to levels below upper reference limit) can be detected (2–4). Re-elevations in CK-MB by more than 50%, can be used to diagnose re-infarctions as early as 18 h after the index event (2). Both cardiac troponin T (cTnT) and cardiac troponin I (cTnI) on the other hand are continuously released from degenerating contractile apparatus in necrotic cardiomyocytes and may show persistent elevations, 7 to 10 days in the case of cTnI and up to 10 to 14 days in the case of cTnT, after the index event (2). The protracted time course of kinetic release of cTnI and cTnT limit their ability to diagnose reinfarction even several days after the index ST-segment elevation myocardial infarction (STEMI) because the cardiac troponin levels will still be on the rise during this period as a result of their normal kinetics, and it is not possible to be sure whether the rise is due to a re-infarction or not. It is because of this important difference in the kinetics between CK-MB, which shows a rapid rise and fall, and the troponins, the American College of Cardiology/American Heart Association Practice guidelines for STEMI specifically state that CK-MB is superior for diagnosing reinfarction (2). This is very relevant as recurrent chest pain is a common complaint of patients admitted for myocardial ischemia and CK-MB plays a vital role in the further evaluation of this complaint.
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1. Jaffe AS, Babuin L, Apple FS. Biomarkers in acute cardiac disease: the present and the future J Am Coll Cardiol 2006;48:1-11.[Abstract/Free Full Text]2. Antman EM, Anbe DT, Armstrong PW, et al. ACC/AHA guidelines for the management of patients with ST-elevation myocardial infarction—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1999 Guidelines for the Management of Patients With Acute Myocardial Infarction) J Am Coll Cardiol 2004;44:671-719.[Free Full Text] 3. Alpert JS, Thygesen K, Antman E, Bassand JP. Myocardial infarction redefined: a consensus document of the Joint European Society of Cardiology/American College of Cardiology Committee for the redefinition of myocardial infarction J Am Coll Cardiol 2000;36:959-969.[Free Full Text] 4. Wu AH, Apple FS, Gibler WB, Jesse RL, Warshaw MM, Valdes R. National Academy of Clinical Biochemistry Standards of Laboratory Practice: recommendations for the use of cardiac markers in coronary artery diseases Clin Chem 1999;45:1104-1121.[Abstract/Free Full Text]
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