Key result
Elevated serum cardiac troponin I levels (≥0.03 ng/ml) demonstrated a 94.6% sensitivity but only 61.9% specificity for acute myocardial infarction, frequently occurring in non-ACS conditions.
Why the study?
Cardiac troponin I levels are elevated not only in ACS patients but also in those with other diseases, complicating diagnosis in the emergency room.
What is the diagnostic specificity of elevated serum cardiac troponin I levels for acute myocardial infarction in patients presenting to the emergency room?
Cross-Sectional (n=1,023)
No
What is the diagnostic specificity of elevated serum cardiac troponin I levels for acute myocardial infarction in patients presenting to the emergency room?
Absolute Event Rate: 94.6% vs 61.9%
Elevated cardiac troponin I levels in the emergency room have high sensitivity but relatively low specificity for acute myocardial infarction, as they are frequently elevated in other conditions.
Troponin I elevation warrants interpretive caution for AMI diagnosis in the ER; leaves open refinement of multimarker algorithms in prospective studies.
BACKGROUND: Although measurement of serum creatine kinase levels, as well as myoglobin levels, has been used for screening patients with acute coronary syndrome (ACS), the specificity of both is low. Measurement of cardiac troponin levels is now extensively used for the diagnosis of ACS because of their superior cardiac specificity. However, troponin levels are reportedly elevated not only in patients with ACS but also in those with other diseases. METHODS AND RESULTS: The clinical characteristics of 1,023 patients (mean age: 63.5+/-16.3 years; males: 665, females: 358) whose serum cardiac troponin I (cTnI) levels had been measured at the initial visit to the emergency room of Toyota Memorial Hospital between April 2004 and March 2005 were retrospectively analyzed. A positive elevation of cTnI was defined as cTnI > or =0.03 ng/ml. There were 432 patients (42.2%) with positive cTnI levels. The cTnI levels (8.48+/-2.64 ng/ml) in patients with acute myocardial infarction (AMI) were greater than those (0.25+/-0.07 ng/ml) in patients with unstable angina pectoris (AP), as well as those (0.04+/-0.01 ng/ml) in patients with stable AP. In terms of the diagnosis of AMI, the sensitivity was high enough (94.6%), but its specificity was relatively low (61.9%). Furthermore, the differentiation between AMI and unstable AP by the cTnI value alone was impossible. The cTnI levels were elevated in patients with a variety of diseases other than ACS, including heart failure, cardiomyopathies, myocarditis, renal failure, tachyarrhythmias, and pulmonary embolism. CONCLUSIONS: Elevation of the cTnI level is frequently observed in patients in the emergency room with common diseases other than ACS.
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Saiki et al. (2007) conducted a cross-sectional in Suspected acute coronary syndrome or other acute conditions (n=1,023). Elevated serum cardiac troponin I (cTnI) vs. Normal cTnI levels was evaluated on Sensitivity and specificity of cTnI ≥0.03 ng/ml for detecting acute myocardial infarction. Elevated serum cardiac troponin I levels (≥0.03 ng/ml) demonstrated a 94.6% sensitivity but only 61.9% specificity for acute myocardial infarction, frequently occurring in non-ACS conditions.
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