Myoglobin for early risk stratification of emergency department patients with possible myocardial ischemia
G B Green1, G W Skarbek-Borowski, D W Chan
1Department of Emergency Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21287-2080, USA. ggreen@jhmi.edu
Insights
Early myoglobin measurement shows high prognostic sensitivity for identifying high-risk patients with possible myocardial ischemia, outperforming creatine kinase-MB (CK-MB) and cardiac troponin T (cTnT). Combining myoglobin with physician judgment significantly improves adverse event prediction in emergency departments.
Area of Science:
- Cardiology
- Emergency Medicine
- Biomarker Research
Background:
- Accurate risk stratification is crucial for emergency department (ED) patients presenting with symptoms suggestive of myocardial ischemia.
- Established cardiac biomarkers like creatine kinase-MB (CK-MB) and cardiac troponin T (cTnT) have limitations in early prognostic assessment.
- Physician judgment alone may miss subtle indicators of cardiac events.
Purpose of the Study:
- To evaluate and compare the prognostic capabilities of early, single-sample myoglobin measurements against CK-MB, cTnT, and physician judgment.
- To determine the utility of myoglobin in identifying patients at risk for adverse events following possible myocardial ischemia.
- To assess myoglobin's prognostic performance across different patient presentations, including chest pain and non-chest pain scenarios.
Main Methods:
- Prospective study involving patients with suspected myocardial ischemia in two urban emergency departments.
- Collection of clinical and serologic data, including myoglobin, CK-MB, and cTnT levels.
- Analysis of 14-day adverse events (AEs) to calculate relative risks and predictive values for each marker and physician judgment.
Main Results:
- Myoglobin demonstrated significantly higher sensitivity (50.8%) in predicting AEs compared to CK-MB (15.4%) and cTnT (24.6%).
- While myoglobin had lower specificity (81.9%) than CK-MB (99.7%) and cTnT (93.1%), its prognostic ability was evident in various presentations.
- The combination of myoglobin and physician decision-making identified 96.9% of patients who subsequently experienced AEs.
Conclusions:
- Early myoglobin measurement offers superior prognostic sensitivity for identifying high-risk patients, potentially detecting cases missed by other markers and physician assessment.
- Myoglobin's diagnostic and prognostic utility supports its consideration for routine use in emergency departments.
- Integrating myoglobin testing with clinical judgment can enhance the identification of patients requiring closer monitoring or intervention.
Objectives:
To determine and compare the prognostic abilities of early, single-sample myoglobin measurement with that of creatine kinase-MB (CK-MB), with cardiac troponin T (cTnT), and with physician judgment in the absence of marker results among emergency department (ED) patients with possible myocardial ischemia.
Methods:
Prospective collection of clinical and serologic data using an identity-unlinked technique from patients with possible myocardial ischemia at two urban EDs. Outcome data concerning the occurrence of adverse events (AEs) during the 14 days after enrollment were used to calculate and compare the relative risks (RRs) and predictive values (with 95% confidence intervals) of the various markers for predicting AEs.
Results:
Among 396 analyzed patients, 65 (16.4%) accrued 104 AEs, including 13 deaths (3.3%) and 31 (7.8%) myocardial infarctions. Myoglobin predicted AEs (RR = 3.36 [95% CI = 2.19 to 5.15]) with significantly higher sensitivity (50.8% [95% CI = 38.6 to 62.9]) than either CK-MB (15.4% [95% CI = 6.6 to 24.2]) or cTnT (24.6% [95% CI = 14.1 to 35.1]), but with lower specificity (81.9% [95% CI = 77.7 to 86.0]; CK-MB = 99.7% [95% CI = 99.1 to 100]; cTnT = 93.1% [95% CI = 90.3 to 95.8]). Myoglobin had prognostic ability among patients with chest pain (3.86 [95% CI = 2.39 to 6.22]) and atypical (non-chest pain) presentations (2.71 [95% CI = 1.09 to 6.71]), including those with a nondiagnostic electrocardiogram (3.11 [95% CI = 1.44 to 6.69]). The combination of myoglobin and physician decision making identified 63 of the 65 patients (96.9% [95% CI = 92.7 to 100]) with subsequent AEs.
Conclusions:
The early prognostic sensitivity of myoglobin may allow identification of some high-risk patients missed by physician judgment, CK-MB, and cTnT. Myoglobin should be considered for use in the ED based on both its diagnostic and prognostic abilities.
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