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Serum concentrations of cardiac troponin I in sudden death: a pilot study
1Wilford Hall Medical Center, and the Office of the Armed Forces Medical Examiner, Lackland Air Force Base, Texas 78236, USA.
Insights
Sudden cardiac death can be linked to ischemic heart disease. Postmortem serum cardiac troponin I (cTnI) levels can help determine if heart disease was the cause of death, even without visible heart damage.
Area of Science:
- Forensic Pathology
- Cardiovascular Medicine
- Biochemistry
Background:
- Sudden cardiac death, often from lethal arrhythmia, is frequently attributed to ischemic heart disease.
- Autopsies may reveal cardiovascular disease but lack evidence of acute myocardial infarction if the patient survived briefly.
- Biochemical markers like creatine kinase MB fraction (CKMB) and cardiac troponin I (cTnI) can detect myocardial injury without morphologic changes.
Purpose of the Study:
- To evaluate the utility of postmortem serum cardiac troponin I (cTnI) levels in identifying ischemic heart disease as a cause of sudden cardiac death.
- To compare the diagnostic accuracy of cTnI with creatine kinase MB fraction (CKMB) in postmortem analysis.
Main Methods:
- A prospective study analyzed serum samples from 28 autopsied patients at the Office of the Chief Medical Examiner of Maryland.
- Serum CKMB and cTnI levels were quantified from subclavian blood samples.
- Statistical analysis compared marker levels between cardiac-related and non-cardiac-related deaths.
Main Results:
- Elevated serum cTnI levels were significantly higher in cardiac-related deaths (mean 93.4 ng/ml) compared to non-cardiac deaths (mean 16.6 ng/ml).
- Serum CKMB levels were also significantly higher in cardiac-related deaths (mean 857.9 ng/ml) versus non-cardiac deaths (mean 116.4 ng/ml).
- Postmortem serum cTnI concentrations above 40 ng/ml were exclusively observed in cardiac-related deaths.
Conclusions:
- Elevated postmortem serum cTnI concentrations are indicative of ischemic heart disease.
- cTnI is a sensitive biomarker for detecting myocardial injury and determining the cause of death, particularly in cases of sudden cardiac death with no visible infarct.
- Quantifying cTnI may be crucial for identifying deaths due to arrhythmia secondary to morphologically undetectable microinfarcts.
Abstract:
Sudden cardiac death due to lethal arrhythmia may be the initial presenting symptom of ischemic heart disease. In many cases, in the absence of trauma, a majority of these deaths will be visually inspected by a medical examiner and released with death being ascribed to atherosclerotic cardiovascular disease, coronary artery disease, arrhythmia, myocardial infarction, or a similar diagnosis. When an autopsy is performed, there may be significant cardiovascular disease but no gross or histologic evidence of an acute myocardial infarct unless the patient survived for several hours following the event. Biochemical assays of creatine kinase MB fraction (CKMB) performed on serum have been used to document myocardial injury in the absence of morphologic changes. Newly developed assays for cardiac troponin I (cTnI) may detect myocardial injury with a greater sensitivity than CKMB. A prospective study was performed on 28 autopsied patients at the Office of the Chief Medical Examiner of the state of Maryland. Subclavian blood was sampled for subsequent analysis of serum CKMB and cTnI. In 3 cases of cardiac-related death, there was insufficient plasma for analysis of both CKMB and cTnI, and only CKMB was quantitated. In 12 cases, hemolysis rendered interpretation questionable. Of the remaining 16 cases, the mean serum CKMB level was 857.9 ng/ml (n = 7) and the cTnI level was 93.4 ng/ml (n = 4) for cardiac-related deaths, compared with mean CKMB levels of 116.4 ng/ml (n = 9) and mean cTnI levels of 16.6 ng/ml (n = 9) for non-cardiac-related deaths. The differences in serum elevation of both CKMB and cTnI noted between the cardiac- and non-cardiac-related deaths were statistically significant. Serum cTnI concentrations >40 ng/ml were only noted in cardiac-related deaths. These data suggest that an elevated postmortem serum concentration of cTnI reflects ischemic heart disease and supports its use in determining cause of death. Quantitation of this analyte may prove useful when death may be due to an arrhythmia following a morphologically undetectable microinfarct.