The incremental value of troponin-I testing in patients with intermediate risk unstable angina
Evan Appelbaum1, M Urooj Zafar, H C Glick
1Cardiovascular Institute, Mount Sinai School of Medicine, New York, USA.
Insights
Agency for Health Care Policy and Research (AHCPR) guidelines effectively risk-stratify unstable angina (UA) patients. High cardiac troponin-I levels significantly improve prognostic value for intermediate-risk UA patients, warranting further investigation.
Area of Science:
- Cardiology
- Emergency Medicine
- Clinical Risk Stratification
Background:
- Agency for Health Care Policy and Research (AHCPR) guidelines stratify unstable angina (UA) patients by risk for death or myocardial infarction (MI).
- Cardiac troponin-I elevation may indicate higher risk, but its added value alongside AHCPR guidelines needs clarification.
Purpose of the Study:
- To determine if cardiac troponin-I offers additional prognostic value beyond standard triage in unstable angina (UA) patients.
- To assess the incremental benefit of troponin-I in risk stratification using history, physical examination, and electrocardiogram.
Main Methods:
- 212 consecutive UA patients with normal CK-MB and elevated troponin-I were analyzed.
- Patients were risk-stratified using AHCPR guidelines.
- The incremental value of routine troponin-I measurements was evaluated.
Main Results:
- Primary events (death/MI) occurred in 35% of high-risk, 15% of intermediate-risk, and 0% of low-risk patients.
- High troponin-I (> or =2.0 ng/dl) was present in 48% of high-risk, 21% of intermediate-risk, and 19% of low-risk patients.
- High troponin-I significantly increased primary event rates only in AHCPR intermediate-risk patients (42.4% vs. 7.3%, p < 0.001).
Conclusions:
- AHCPR guidelines effectively risk-stratify patients with unstable angina (UA).
- Elevated cardiac troponin-I provides significant prognostic value in intermediate-risk UA patients.
- Further evaluation of high troponin-I in larger trials of intermediate-risk UA patients is recommended.
Background:
Classification of patients with unstable angina (UA) by Agency for Health Care Policy and Research (AHCPR) guidelines in the emergency department reliably stratifies risk of death or myocardial infarction (MI) for triage to outpatient evaluation (low-risk), hospitalization (high-risk), or additional testing (intermediate-risk). Cardiac troponin-I elevation may identify patients at higher risk, but the incremental value may vary with AHCPR clinical risk.
Hypothesis:
The objective of this study was to determine whether cardiac troponin-I had any additional value beyond triage based upon history, physical examination, and electrocardiogram, in the evaluation of patients with UA.
Methods:
In all, 212 consecutive patients with UA and normal serum creatine kinase (CK)-MB levels and elevated troponin-I were risk stratified by AHCPR guidelines to evaluate the incremental value of adding routine troponin-I measurements to our current model for risk stratification.
Results:
Primary events (death/nonfatal MI) occurred in 35% of high-risk, 15% of intermediate-risk, and 0% of low-risk patients (p < 0.001 by chi-square for trend). High troponin-I (> or =2.0 ng/dl) occurred in 48% of high-risk, 21% of intermediate-risk, and 19% of low-risk patients. The remaining patients in each risk group had indeterminate troponin-I levels (> or =0.4 < 2 ng/dl). Of those with high troponin-I, a primary event occurred in 36, 42, and 0% in the respective high-, intermediate-, and low-risk groups (p < 0.001). High troponin-I levels corresponded with a statistically significant increased rate of primary events only in patients at AHCPR intermediate risk: 42.4 vs. 7.3%, p < 0.001.
Conclusion:
The AHCPR guidelines risk stratify patients with UA. High troponin-I adds significant (p < 0.001) prognostic value in the patients at AHCPR intermediate risk and should be evaluated further in larger trials of such patients.
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