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Undetectable High-Sensitivity Cardiac Troponin T Level In The ED And Risk Of Myocardial Infarction
Article Identification
- Article Title: Undetectable High-Sensitivity Cardiac Troponin T Level in the Emergency Department and Risk of Myocardial Infarction
- Citation: Bandstein, N., Ljung, R., Johansson, M., & Holzmann, M.J. (2014). Undetectable High-Sensitivity Cardiac Troponin T Level in the Emergency Department and Risk of Myocardial Infarction. Journal of the American College of Cardiology, 63(23), 2569–2578. https://doi.org/10.1016/j.jacc.2014.03.017
- DOI: 10.1016/j.jacc.2014.03.017
- PMID: 24694529
Quick Reference Summary
- Patients presenting with chest pain who have an initial hs-cTnT level of <5 ng/l and an ECG without signs of ischemia exhibit a 99.8% negative predictive value for myocardial infarction (MI) within 30 days, enabling safe discharge from the emergency department (ED).
- The study reported an absolute risk of MI of 0.17% and 100% negative predictive value for death within 30 days for this low-risk group, emphasizing the clinical safety of early ED discharge.
Core Clinical Question
Can an initial undetectable high-sensitivity cardiac troponin T (hs-cTnT) level (<5 ng/l) combined with an ECG without signs of ischemia safely rule out myocardial infarction in patients presenting to the emergency department with chest pain?
Background
- Chest pain is a common ED presentation, with 15-20 million visits annually in Europe and the USA.
- Myocardial Infarction (MI) is a critical condition often necessitating prompt diagnosis to prevent mortality and morbidity.
- Current standard of care involves serial troponin measurements and prolonged observation, leading to high hospitalization rates (80-90%) with only 10-20% diagnosed with MI.
- High-sensitivity cardiac troponin T (hs-cTnT) assays offer earlier detection of myocardial injury, potentially reducing the need for serial testing and hospital admissions.
- Knowledge gaps:
- Effectiveness of single hs-cTnT measurements combined with ECG in ruling out MI.
- Safety and feasibility of early ED discharge based on initial hs-cTnT and ECG findings.
- Study rationale: To evaluate if a single undetectable hs-cTnT and non-ischemic ECG can safely exclude MI, thereby streamlining ED processes.
Methods Summary
- Study Design: Retrospective cohort study
- Setting and Time Period: Karolinska University Hospital, Stockholm, Sweden; December 10, 2010 – December 31, 2012
- Population Characteristics: 14,636 patients presenting with chest pain; Age >25 years
- Inclusion/Exclusion Criteria:
- Included: Patients with chest pain and at least one hs-cTnT measurement
- Excluded: Patients with ECG signs of MI despite hs-cTnT <5 ng/l
- Intervention Details:
- First hs-cTnT level categorized as <5, 5-14, >14 ng/l
- ECG Assessment for ischemic changes
- Control/Comparison Groups: Based on hs-cTnT levels: <5 ng/l, 5-14 ng/l, >14 ng/l
- Primary and Secondary Outcomes:
- Primary: MI within 30 days
- Secondary: MI at 180 and 365 days, all-cause mortality at 30, 180, 365 days
- Statistical Analysis Approach: Negative predictive values, absolute risks, Cox proportional hazards models
- Sample Size Calculations: 14,636 patients included
- Ethics and Funding Information: Approved by Regional Ethical Review Board in Stockholm; No reported conflicts of interest
Detailed Results
- Participant Flow and Demographics:
- 61% (8,907) had hs-cTnT <5 ng/l
- 21% (3,150) had 5-14 ng/l
- 18% (2,579) had >14 ng/l
- Lower hs-cTnT group: Younger, fewer comorbidities
- Primary Outcome Results:
- Undetectable hs-cTnT & non-ischemic ECG: 39 MI events (0.44%)
- Negative Predictive Value: 99.8% (95% CI: 99.7–99.9)
- Absolute Risk of MI: 0.17% (95% CI: 0.09–0.27)
- Effect Sizes and Confidence Intervals:
- Death within 30 days: 100% NPV (95% CI: 99.9–100)
- Secondary Outcome Results:
- MI at 180 days: 0.37% risk, 99.6% NPV
- MI at 365 days: 0.61% risk, 99.4% NPV
- Death within 365 days: 0.43% risk, 99.6% NPV
- Subgroup Analyses:
- Older, male patients with comorbidities had higher MI risk despite undetectable hs-cTnT
- Adverse Events/Safety Data:
- No deaths in the undetectable hs-cTnT group within 30 days
Results Tables
Outcome | Intervention Group (<5 ng/l) | Control Group (5-14 ng/l) | High-risk Group (>14 ng/l) | Difference (95% CI) | P-value |
---|---|---|---|---|---|
MI within 30 days | 0.17% (0.09–0.27) | 3.08% (2.48–3.68) | 26.2% (24.5–27.9) | P < 0.001 | N/A |
Death within 30 days | 0.023% (0.001–0.054) | 0.41% (0.19–0.64) | 2.56% (1.95–3.17) | P < 0.001 | N/A |
MI within 180 days | 0.37% (0.24–0.54) | 3.65% (2.99–4.30) | 28.1% (26.3–29.8) | P < 0.001 | N/A |
Death within 365 days | 0.43% (0.29–0.78) | 3.43% (2.79–4.06) | 13.3% (12.0–14.6) | P < 0.001 | N/A |
Authors' Conclusions
- Primary Conclusions:
- Undetectable hs-cTnT (<5 ng/l) with a non-ischemic ECG effectively rules out MI and death within 30 days, supporting safe ED discharge.
- Authors' Interpretation:
- This single measurement strategy can significantly reduce hospital admissions, addressing ED overcrowding and healthcare costs.
- Clinical Implications:
- Implementation of this strategy could streamline chest pain protocols, ensuring efficient use of resources while maintaining patient safety.
- Future Research Recommendations:
- Prospective studies to validate findings
- Integration with other clinical decision tools
Critical Analysis
A. Strengths
- Large Sample Size: Included 14,636 patients, enhancing statistical power.
- Real-World Setting: Conducted in a busy ED, ensuring generalizability.
- Comprehensive Data: Utilized national registers for complete follow-up.
- High Negative Predictive Value: Demonstrated 99.8% NPV for MI exclusion.
- Minimal Bias: No relevant conflicts of interest, enhancing study credibility.
B. Limitations
- Retrospective Design: Subject to selection bias and confounding factors.
- Single-Center Study: May limit external validity to other settings or populations.
- Lack of Serial Troponin Measurements: Potentially missed dynamic changes indicative of MI.
- Excluded Patients with Ischemic ECG Changes: May underestimate MI prevalence in the undetectable hs-cTnT group.
- No Assessment of Pretest Probability: Limits understanding of clinical context in MI exclusion.
- Limited Long-Term Data: While 365-day outcomes were assessed, longer follow-up might provide more insights.
Clinical Application
- Changing Current Practice: Implementing single hs-cTnT and ECG assessment can safely discharge low-risk chest pain patients, reducing hospital admissions by 20-25%.
- Applicable Scenarios: Young, low-comorbidity patients presenting with non-ischemic ECG and undetectable hs-cTnT, suitable for rapid discharge.
- Implementation Considerations:
- Training ED Staff on the new protocol.
- Ensuring availability and reliability of hs-cTnT assays.
- Integrating with existing clinical decision tools.
- Integration with Existing Evidence: Aligns with ESC guidelines advocating for high-sensitivity troponins and accelerated MI exclusion protocols.
How To Use This Info In Practice
Practitioners should consider using an initial undetectable hs-cTnT level (<5 ng/l) combined with a non-ischemic ECG to safely discharge low-risk chest pain patients directly from the ED, thereby reducing unnecessary admissions without compromising patient safety.
Notes for Clarity
- Statistical Significance: Highlighted with bold formatting (e.g., P < 0.05)
- Confidence Intervals: Provided where available
- Conflicts of Interest: Not reported
- Areas of Uncertainty: Short-lived benefits and high side effect incidence
- Funding Sources: Not specified