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Troponin I and myocardial injury in the ICU
J S Noble1, A M Reid, L V Jordan
1Department of Anaesthesia, Victoria Infirmary, Glasgow, UK.
Insights
Elevated cardiac troponin I (cTnI) levels are common in ICU patients, indicating frequent myocardial injury. This protein marker is a sensitive indicator of heart muscle damage in critical care settings.
Area of Science:
- Cardiology
- Biochemistry
- Critical Care Medicine
Background:
- Cardiac troponin I (cTnI) is a heart-specific protein.
- Elevated cTnI in serum signifies myocardial cell injury.
- Early detection of cardiac injury is crucial in intensive care units (ICUs).
Purpose of the Study:
- To compare the diagnostic utility of cTnI against creatinine kinase MB (CK MB), myoglobin, and electrocardiogram (ECG) for detecting myocardial injury.
- To assess the incidence and clinical correlates of elevated cTnI in a general ICU population.
Main Methods:
- Prospective observational study in 109 medical and surgical ICU patients.
- Daily serum analysis for cTnI, myoglobin, and CK MB.
- Daily clinical observations and 12-lead ECG recordings.
- Comparison with an unmatched control group (n=98) from emergency admissions without cardiac diagnoses.
Main Results:
- Increased serum cTnI (> 0.1 microgram/L) was detected in 70.6% (n=77) of ICU patients.
- Higher cTnI concentrations correlated with tachycardia, arrhythmia, hypotension, and inotropic drug use.
- Control group subjects consistently showed cTnI levels < 0.1 microgram/L.
Conclusions:
- Elevated serum cTnI concentrations are frequent in ICU patients, suggesting a high incidence of cardiac injury.
- cTnI demonstrates significant utility in identifying myocardial injury within the critical care setting.
- Further investigation into the causes and implications of cTnI elevation in ICUs is warranted.
Abstract:
Cardiac troponin I (cTnI) is a protein that is specific to heart muscle. Increased concentrations appear in serum after myocardial cell injury. cTnI was compared with creatinine kinase MB (CK MB), myoglobin and the 12-lead ECG for detection of myocardial injury in an unselected series of 109 medical and surgical ICU patients. Clinical observations and daily 12-lead ECG were recorded prospectively. Samples for cTnI, myoglobin and CK MB serum analysis were collected each day. Increased serum cTnI concentrations (> 0.1 microgram litre-1) were observed in 70.6% (n = 77) of the ICU group. Tachycardia, arrhythmia, hypotension and treatment with inotropic drugs were associated with higher concentrations. The standardized mortality ratio by APACHE III for the ICU sample was 0.98. All subjects in an unmatched control group of 98 medical unit emergency admissions without a primary cardiac diagnosis had serum cTnI concentrations < 0.1 microgram litre-1. We conclude that increased serum cTnI concentrations occur frequently in the ICU suggesting that there is a high incidence of cardiac injury in these patients.
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