Early Diagnostic Efficiency of Cardiac Troponin I and Troponin T for Acute Myocardial Infarction

Abstract

Objective: To compare the early diagnostic efficiency of the cardiac troponin I (cTn-I) level with that of the cardiac troponin T (cTn-T) level, as well as the creatine kinase (CK), CK-MB, and myoglobin levels, for acute myocardial infarction (AMI) in patients without an initially diagnostic ECG presenting to the ED within 24 hours of the onset of their symptoms. Methods: A prospective, observational, cohort study was performed involving chest pain patients admitted to a large urban community hospital. Participants were consecutive consenting ED chest pain patients 230 years of age. Exclusions included duration of symptoms >24 hours, inability to complete data collection, receipt of CPR, and ST-segment elevation on the initial ECG. Measurements included levels of cTn-I, cTn-T, CK, CK-MB, and myoglobin at the time of presentation and 1, 2, 6, and 12-24 hours after presentation as well as presenting ECG and clinical follow-up. Confirmation of the diagnosis of AM1 was based on World Health Organization criteria. Results: Of the 177 patients included in the study, 27 (15%) were diagnosed as having AMIs. The sensitivities of all 5 biochemical markers for AM1 were poor at the time of ED presentation (3.7-33.3%) but rose significantly over the study period. The sensitivity of cTn-T was significantly better than that of cTn-I over the initial 2 hours, but both markers' sensitivities were low (<60%) during this time frame. The cTn-I was significantly more specific for AM1 than was the cTn-T, but not significantly better than CK-MB or myoglobin. Likelihood ratio analysis showed that the biochemical markers with the highest positive likelihood ratios for AM1 during the first 2 hours following ED presentation were myoglobin and CK-MB. From 6 through 24 hours, the positive likelihood ratios for cTn-I, CK-MB, and myoglobin were superior to those of CK and cTn-T. Conclusions: cTn-I, CK-MB, and myoglobin are significantly more specific for AM1 than are CK and cTn-T. Myoglobin is the biochemical marker having the highest combination of sensitivity, specificity, and negative predictive value for AM1 within 2 hours of ED presentation. Neither cTn-I nor cTn-T offers significant advantages over myoglobin and CK-MB in the early ( 1 2 hours) initial screening for AMI. The cardiac troponins are of benefit in identifying AM1 2 6 hours after presentation.

Assessment of the Multiple-Biomarker Approach for Diagnosis of Myocardial Infarction in Patients Presenting with Symptoms Suggestive of Acute Coronary Syndrome

“…The studies that have been performed have compared either cTnT or cTnI against CK-MB and myoglobin (38 ). In the studies that have used the newer-generation cardiac troponin assays, the clinical sensitivities of cardiac troponin outperformed those of both myoglobin and CK-MB, findings that are consistent with the fact that increases in cardiac troponin concentration begin 2 to 4 h after the onset of ischemic symptoms (29,(35)(36)(37)(38).…”

Analytical evaluation of two automatic methods to measure blood CK-MB mass and troponin I

“…The wide diagnostic window of troponin (10± 15 days) may be due to its profound localization. The cutoå value of 5 mg l ± 1 for CK-MB mass, a method which is more standardized than troponin, agrees with that proposed by the manufacturer and some authors working with other commercial kits [42,43]. We have demonstrated that the sensitivity of CK-MB mass for the diagnosis of AMI during the ® rst 6 h of precordial pain is higher than troponin I using 0.77 and 1.5 mg l ± 1 as the cutoå values.…”

Serum Cardiac Troponin I Concentrations in Dogs with Systemic Inflammatory Response Syndrome

“…cTnI contributed significantly to the prognostic power of another scoring system for dogs with severe systemic diseases, the physiologic and laboratory evaluation (APPLE) full score in those patients 38. Using immunoassays with high sensitivity for cTnI improved the sensitivity for detection of myocardial injury as compared to older generation cTnI assays 7, 39, 40, 41…”