Article Identification

• Article Title: [Not Provided]
• Authors: [Authors information not available in the provided text]
• Journal Name, Year, Volume, Issue: [Journal details not available in the provided text]
• Type of Study: Retrospective Cohort Study
• DOI/PMID: [DOI/PMID not available in the provided text]

Quick Reference Summary

• An initial high-sensitivity cardiac troponin T (hs-cTnT) level of <5 ng/l combined with no ischemic signs on an ECG demonstrated a 99.8% negative predictive value for myocardial infarction (MI) within 30 days and a 100% negative predictive value for death.
• The study suggests that patients presenting with chest pain to the emergency department (ED) meeting these criteria can be safely discharged, potentially reducing hospital admissions without compromising patient safety.

Core Clinical Question

Can an undetectable (<5 ng/l) high-sensitivity cardiac troponin T level combined with an ECG lacking ischemic signs reliably rule out myocardial infarction and mortality within 30 days in patients presenting with chest pain to the emergency department?

Background

• Disease/Condition Overview: Chest pain is a common ED presentation, often benign but sometimes indicative of myocardial infarction (MI), a life-threatening condition.
• Prior Data on the Topic:
  • Previous high-sensitivity troponin assays required ≥6 hours from symptom onset for detection, necessitating serial testing and hospital admission.
  • Emerging high-sensitivity cardiac troponin T (hs-cTnT) assays offer earlier detection of myocardial damage.
• Current Standard of Care:
  • Guidelines recommend repeated biomarker testing 3-6 hours post-presentation for chest pain patients with normal clinical findings and ECGs, leading to hospital admissions.
  • Only 10-20% of admitted chest pain patients are diagnosed with MI.
• Knowledge Gaps Addressed by Study:
  • Potential to rule out MI without serial biomarker testing or prolonged observation.
  • Evaluation of hs-cTnT and ECG criteria to safely discharge patients directly from the ED.
• Study Rationale: Reducing unnecessary hospital admissions could alleviate ED overcrowding and decrease healthcare costs while maintaining patient safety.

Methods Summary

• Study Design: Retrospective cohort study.
• Setting and Time Period: Karolinska University Hospital, Stockholm, Sweden, from December 10, 2010, to December 31, 2012.
• Population Characteristics: Patients >25 years presenting to the ED with chest pain and at least one hs-cTnT measurement.
• Inclusion/Exclusion Criteria:
  • Included: All chest pain patients >25 years with ≥1 hs-cTnT level measured in the ED.
  • Excluded: Patients with a first hs-cTnT <5 ng/l but with ischemic ECG changes indicative of MI.
• Intervention Details: Assessment based on initial hs-cTnT levels (<5, 5-14, >14 ng/l) and ECG findings.
• Control/Comparison Group Details: Comparison across hs-cTnT level groups.
• Primary and Secondary Outcomes:
  • Primary: Fatal or nonfatal type 1 MI within 30 days.
  • Secondary: MI within 180 and 365 days; all-cause mortality within 30, 180, and 365 days.
• Statistical Analysis Approach: Calculation of negative predictive values, absolute risks, and incidence rates with 95% confidence intervals; Cox proportional hazards model for mortality risk.
• Sample Size Calculations: Included all eligible patients (N=14,636).
• Ethics and Funding Information: Approved by the Regional Ethical Review Board in Stockholm; compliance with the Declaration of Helsinki. [Specific funding sources not provided]

Detailed Results

Participant Flow and Demographics

Category	Details
Total ED Visits	330,821
Chest Pain Presentations	15,549 (4.7%)
Included in Study	14,636 (>25 years with ≥1 hs-cTnT)
hs-cTnT Levels <5 ng/l	8,907 (61%)
hs-cTnT Levels 5-14 ng/l	3,150 (21%)
hs-cTnT Levels >14 ng/l	2,579 (18%)

Demographics: Patients with <5 ng/l were younger (mean age 47), more likely female (53%), and had fewer comorbidities compared to higher hs-cTnT groups.

Primary Outcome Results

hs-cTnT Level	MI within 30 Days	Negative Predictive Value for MI within 30 Days
<5 ng/l	0.17% (15/8,907)	99.8% (95% CI: 99.7 to 99.9)
5-14 ng/l	3.08% (97/3,150)	96.9% (95% CI: 96.3 to 97.5)
>14 ng/l	26.2% (676/2,579)	73.8% (95% CI: 72.1 to 75.5)

Secondary Outcome Results

Outcome	<5 ng/l	5-14 ng/l	>14 ng/l
Death within 30 Days	0.023% (2/8,907) - 100% NPV (95% CI: 99.9 to 100.0)	0.41% (13/3,150)	2.56% (66/2,579)
Long-term Mortality (365 Days)	0.43% (38/8,907) - NPV: 99.6%	3.43% (108/3,150) - NPV: 96.6%	13.3% (342/2,579) - NPV: 86.7%

Subgroup Analyses

• Among patients with hs-cTnT <5 ng/l and no ischemic ECG changes, 39 (0.44%) experienced MI within 30 days.
• Detailed examination of these cases revealed factors such as age, sex, previous cardiovascular disease, and smoking status contributed to MI occurrence despite initial low hs-cTnT levels.

Adverse Events/Safety Data

• No deaths occurred in the <5 ng/l group within 30 days.
• Two cardiovascular deaths occurred within the first year among the <5 ng/l group.

Authors' Conclusions

• Primary Conclusions: An initial hs-cTnT level of <5 ng/l combined with no ischemic ECG changes effectively rules out MI with nearly 100% accuracy within 30 days.
• Interpretation of Results: This diagnostic strategy could safely enable direct discharge of low-risk chest pain patients from the ED, minimizing unnecessary hospital admissions.
• Clinical Implications: Implementing this approach may reduce ED overcrowding and healthcare costs without increasing the risk of adverse outcomes.
• Future Research Recommendations: Further studies to validate these findings in different populations and settings, and to explore the integration of hs-cTnT criteria into existing clinical decision rules.

Critical Analysis

A. Strengths:

• Large Sample Size: Included 14,636 consecutive patients, enhancing the robustness of findings.
• Comprehensive Data: Utilized national registers ensuring complete follow-up and accurate outcome assessment.
• Real-World Setting: Conducted in a high-volume ED, reflecting practical clinical environments.
• Clear Predictive Metrics: High negative predictive values provide strong evidence for clinical application.

B. Limitations:

• Retrospective Design: Potential for unmeasured confounding factors influencing outcomes.
• Single-Center Study: Limits generalizability to other hospitals or geographic regions.
• Lack of Serial Biomarker Testing: The study did not assess outcomes with serial hs-cTnT measurements, which are standard in some protocols.
• Missing Data on Pretest Probability: Absence of clinical probability assessments may affect the applicability of results to all patient subsets.

C. Literature Context

Not explicitly provided as no literature review was included in the discussion sections beyond comparisons to similar studies.

Clinical Application

• Implementing an initial hs-cTnT <5 ng/l with no ischemic ECG changes can safely identify chest pain patients at minimal risk for MI or death within 30 days, allowing for safe discharge from the ED.
• This strategy is particularly applicable to low-risk populations presenting with chest pain, potentially streamlining ED workflows and reducing unnecessary admissions.

How To Use This Info In Practice

Clinicians should consider utilizing an initial hs-cTnT level of <5 ng/l combined with a non-ischemic ECG to safely discharge low-risk chest pain patients from the emergency department, thereby optimizing patient flow and resource utilization.