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Evidence-Based Laboratory Medicine and Test Utilization |
1 The Research Institute at Lakeridge Health, Oshawa, ON, Canada.
Programs of2
Critical Care Cardiopulmonary and3
Emergency Medicine, Lakeridge Health, Oshawa, ON, Canada.
4 Department of Pathology, Women and Infants Hospital, Providence, RI.
5 Immunotech S.A.S., a Beckman Coulter subsidiary, Marseilles, France.
6 Cardiovascular Division and Division of Laboratory Medicine, Mayo Clinic, Rochester, MN.
aAddress correspondence to this author at: 216 Wellington St., Whitby, ON, Canada L1N 5L8.
Background: The American Heart Association (AHA) case definition for acute myocardial infarction (AMI) requires an "adequate set" of biomarkers: 2 measurements of the same marker at least 6 h apart. A sensitive troponin assay might detect significant changes in concentration earlier. We determined AMI prevalence, using protocols with shorter intervals between measurements, with and without incorporating the time from onset of symptoms.
Methods: The AHA case definition was used to retrospectively assign a diagnosis in 258 patients presenting to the emergency department with symptoms of cardiac ischemia. AMI was diagnosed if either specimen in an adequate set had a cardiac troponin I (cTnI) above the 99th percentile (AccuTnI® >0.04 µg/L; Beckman Coulter) with a 
20% change in concentration between specimens. We assessed positivity for AMI after progressively decreasing the time interval between specimens in specimen sets. In addition, for each patient, 2 additional specimen pairs were selected: pairs collected at least 1 h apart with 1 specimen being either 3 h after onset or 6 h after onset.
Results: When we used the AHA definition, the AMI prevalence was 35.7%. Prevalence was not significantly diminished when the interval between specimens was 5, 4, or 3 h (36.4%, 34.5%, and 33.7%, respectively) compared with the AHA 6 h interval. When the time from onset of symptoms was included in the specimen selection algorithm, a 1-h interval was sufficient provided that at least one specimen was collected 6 h after onset (prevalence, 34.1%; P = 0.48 vs AHA definition).
Conclusion: A sensitive cTnI assay in specimen sets with time intervals 3 h, or having one specimen 6 h after onset, gave an AMI prevalence equivalent to the AHA definition.
The following articles in journals at HighWire Press have cited this article:
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  P. A. Kavsak, A. M. Newman, D. T. Ko, G. E. Palomaki, V. Lustig, A. R. MacRae, and A. S. Jaffe Is a Pattern of Increasing Biomarker Concentrations Important for Long-Term Risk Stratification in Acute Coronary Syndrome Patients Presenting Early after the Onset of Symptoms? Clin. Chem., April 1, 2008; 54(4): 747 - 751. [Abstract] [Full Text] [PDF]
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 K. Thygesen, J. S. Alpert, H. D. White, and on behalf of the Joint ESC/ACCF/AHA/WHF Task Force Universal Definition of Myocardial Infarction J. Am. Coll. Cardiol., November 27, 2007; 50(22): 2173 - 2195. [Full Text] [PDF]
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 K. Thygesen, J. S. Alpert, H. D. White, on behalf of the Joint ESC/ACCF/AHA/WHF Task Force, TASK FORCE MEMBERS: Chairpersons: Kristian Thygese, Biomarker Group: Allan S. Jaffe, Coordinator (USA), ECG Group: Bernard Chaitman, Co-ordinator (USA), P, Imaging Group: Richard Underwood, Coordinator (UK), Intervention Group: Jean-Pierre Bassand, Co-ordina, Clinical Investigation Group: Paul W. Armstrong, C, et al. Universal Definition of Myocardial Infarction Circulation, November 27, 2007; 116(22): 2634 - 2653. [Full Text] [PDF]
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 Task Force Members, K. Thygesen, J. S. Alpert, H. D. White, Biomarker Group, A. S. Jaffe, F. S. Apple, M. Galvani, H. A. Katus, L. K. Newby, et al. Universal definition of myocardial infarction: Kristian Thygesen, Joseph S. Alpert and Harvey D. White on behalf of the Joint ESC/ACCF/AHA/WHF Task Force for the Redefinition of Myocardial Infarction Eur. Heart J., October 2, 2007; 28(20): 2525 - 2538. [Full Text] [PDF]
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NACB WRITING GROUP MEMBERS, D. A. Morrow, C. P. Cannon, R. L. Jesse, L. K. Newby, J. Ravkilde, A. B. Storrow, A. H.B. Wu, and R. H. Christenson National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines: Clinical Characteristics and Utilization of Biochemical Markers in Acute Coronary Syndromes Circulation, April 3, 2007; 115(13): e356 - e375. [Full Text] [PDF]
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NACB WRITING GROUP MEMBERS, D. A. Morrow, C. P. Cannon, R. L. Jesse, L. K. Newby, J. Ravkilde, A. B. Storrow, A. H.B. Wu, R. H. Christenson, NACB COMMITTEE MEMBERS, et al. National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines: Clinical Characteristics and Utilization of Biochemical Markers in Acute Coronary Syndromes Clin. Chem., April 1, 2007; 53(4): 552 - 574. [Full Text] [PDF]
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P. A. Kavsak, A. M. Newman, V. Lustig, A. R. MacRae, G. E. Palomaki, D. T. Ko, J. V. Tu, and A. S. Jaffe Long-Term Health Outcomes Associated with Detectable Troponin I Concentrations Clin. Chem., February 1, 2007; 53(2): 220 - 227. [Abstract] [Full Text] [PDF]
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A. S. Jaffe, L. Babuin, and F. S. Apple Reply J. Am. Coll. Cardiol., December 5, 2006; 48(11): 2358 - 2359. [Full Text] [PDF]
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A. S. Jaffe Chasing Troponin: How Low Can You Go if You Can See the Rise? J. Am. Coll. Cardiol., November 7, 2006; 48(9): 1763 - 1764. [Full Text] [PDF]
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P. A. Kavsak, A. R. MacRae, G. E. Palomaki, A. M. Newman, D. T. Ko, V. Lustig, J. V. Tu, and A. S. Jaffe Health Outcomes Categorized by Current and Previous Definitions of Acute Myocardial Infarction in an Unselected Cohort of Troponin-Naive Emergency Department Patients Clin. Chem., November 1, 2006; 52(11): 2028 - 2035. [Abstract] [Full Text] [PDF]
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J. S. Alpert Will the real myocardial infarction please stand up? Clin. Chem., May 1, 2006; 52(5): 795 - 796. [Full Text] [PDF]
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