LETTER TO THE EDITOR
Comparison of troponin T and creatine Kinase-MB fraction in evaluating cardiac patients postoperatively
Carol Chen-Scarabelli, MSN, ARNP-CS* and
Tiziano Scarabelli, MD
* Jackson Memorial Hospital, University of Miami, Division of Cardiothoracic Surgery, 1611 NW 12th Avenue, East Tower 3rd Floor, Room 3072, Miami, Florida 33136, USA
St. John’s Hospital and Medical Center, Division of Cardiology, Wayne State University, Detroit, Michigan, USA
cchen{at}med.miami.edu
Dr. Januzzi and colleagues in a recent study (1) published in the Journal suggest replacement of creatine kinase-MB fraction (CK-MB) with serum troponin testing for postoperative evaluation of the cardiac surgical patient. An important point to remember is the release pattern of these markers. Although the rise (CK-MB 4 to 8 h; CK-MB isoform 2 to 6 h; cardiac troponin I [cTnI] 4 to 6 h; cardiac troponin T [cTnT] 4 to 8 h) and peak (CK-MB 12 to 24 h; CK-MB isoform 18 h; cTnI 12 h; cTnT 12 to 28 h) are similar, the markers differ greatly in their return to normal (CK-MB 72 to 96 h; CK-MB isoform <24 h; cTnI 3 to 10 days; cTnT 7 to 10 days) (2).
Because of their prolonged elevation in the blood (up to 10 days), cardiac troponins may reflect a summation of preoperative, perioperative, and postoperative events, thereby limiting the ability to detect perioperative injury exclusively. In contrast, CK-MB and its isoforms have a more rapid clearance and return to normal more quickly, thus facilitating better timing of myocardial injury (3). The long circulating half-lives of the cardiac troponins make it difficult to distinguish new episodes of myocardial necrosis from earlier episodes (4,5). Hence, reinfarctions may be difficult to diagnose with the sole use of cardiac troponin assays, if the initial myocardial infarction (MI) occurred within a week of cardiac surgery. Subsequently, both CK-MB and cardiac troponins are concurrently useful and not mutually exclusive in the diagnosis of postoperative MI and reinfarction after coronary artery bypass graft surgery.
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References
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- Januzzi JL, Lewandrowski K, MacGillivray TE, et al. A comparison of cardiac troponin T and creatine kinase-MB for patient evaluation after cardiac surgery. J Am Coll Cardiol. 2002;39:1518–1523[Abstract/Free Full Text]
- Abbott Diagnostics Educational Services. 1999. Troponin I: Information for Physicians. Abbott Park, IL
- Birdi I, Angelini GD, Bryan AJ. Biochemical markers of myocardial injury during cardiac operations. Ann Thorac Surg. 1997;63:879–884[Abstract/Free Full Text]
- Califf RM, Abdelmeguid AE, Kuntz RE, et al. Myonecrosis after revascularization procedures. J Am Coll Cardiol. 1998;31:241–251[Abstract/Free Full Text]
- 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]
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A. S. Adabag, T. Rector, S. Mithani, J. Harmala, H. B. Ward, R. F. Kelly, J. T. Nguyen, E. O. McFalls, and H. E. Bloomfield
Prognostic Significance of Elevated Cardiac Troponin I After Heart Surgery
Ann. Thorac. Surg.,
May 1, 2007;
83(5):
1744 - 1750.
[Abstract]
[Full Text]
[PDF]
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