Cardiac troponin I measurement using the ACS:180 to predict four-year cardiac event rate
Paul O Collinson1, Gloria H Gaynor, David C Gaze
1Department of Chemical Pathology, 2nd Floor Jenner Wing, St George's Hospital and Medical School, Blackshaw Road, London SW17 0QT, UK. paul.collinson@stgeorges.nhs.uk
Insights
Cardiac troponin I (cTnI) levels on admission can predict future cardiac events in patients with suspected non-ST elevation myocardial infarction (NSTEMI). A cTnI above 0.16 microg/L indicates a higher risk of cardiac events within four years.
Area of Science:
- Cardiology
- Biomarker Analysis
- Clinical Diagnostics
Background:
- Evaluating cardiac troponin I (cTnI) for prognostic risk stratification in acute coronary syndromes (ACS).
- Assessing the utility of the ACS:180 assay for cTnI measurement.
- Long-term follow-up of cardiac events in patients admitted to a coronary care unit.
Purpose of the Study:
- To evaluate the prognostic ability of cardiac troponin I (cTnI) measurements using the ACS:180 assay.
- To determine the predictive value of cTnI for cardiac events and mortality.
- To stratify risk in patients admitted with suspected acute coronary syndromes.
Main Methods:
- Sequential admissions to a coronary care unit were studied.
- Blood samples analyzed for cTnI using chemiluminescent immunoassay (ACS:180) at multiple time points.
- Kaplan-Meier survival plots and log-rank analysis used for risk prediction thresholds.
Main Results:
- 289 patients studied (139 STEMI, 150 NSTEMI).
- Admission cTnI did not predict outcomes in STEMI patients.
- In NSTEMI patients, admission and peak cTnI levels predicted increased risk of death or myocardial infarction readmission.
Conclusions:
- A cTnI level exceeding 0.16 microg/L on admission or during hospitalization predicts an increased cardiac event rate at four years.
- cTnI measurement on the ACS:180 is valuable for prognostic risk stratification in suspected NSTEMI.
- Peak cTnI levels are significant predictors of mortality in NSTEMI patients.
Background:
This study aimed at evaluating the ability of cardiac troponin I (cTnI) measurement on the ACS:180 for prognostic risk stratification. Sequential admissions to the coronary care unit of a busy district general hospital were studied. All patients were followed up for a maximum of 4.3 years and cardiac events, either cardiac death, readmission with acute myocardial infarction or admission with acute unstable angina were documented.
Methods:
Blood samples were taken on admission and at 4 and 12 h. A serum aliquot was taken and stored frozen at -70 degrees C. The frozen aliquots were subsequently analysed for cTnI by chemiluminescent immunoassay using an ACS:180. Patients were categorized into those with or without ST segment elevation on the presenting electrocardiogram. The optimized decision threshold for mortality and event prediction was then determined by log-rank analysis and by construction of Kaplan-Meier survival plots.
Results:
A total of 289 patients (196 men) median age 65.3 years, range 27.4-87.9 years were studied. Out of this, 139 had ST elevation myocardial infarction (STEMI) and 150 had suspected non-STEMI (NSTEMI). Full data were available from 278 patients. Admission cTnI did not predict any of the endpoints in the STEMI group. In patients admitted with suspected NSTEMI, admission and peak cTnI predicted increased risk of death or readmission with acute myocardial infarction. In addition, peak cTnI predicted increased risk of death.
Conclusion:
A cTnI exceeding 0.16 microg/L on admission or during hospital stay predicted an increased cardiac event rate at four years in patients admitted with suspected NSTEMI.
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