Evaluation of 6 cardiac troponin assays in patients with acute coronary syndrome.

OBJECTIVE: An increasing body of evidence has demonstrated the value of strategies based on cardiac troponin (cTn) assays in the diagnosis, prognosis and monitoring of patients with acute coronary syndrome (ACS). We evaluated the performance and the practicability of 6 commercially available assays (5 cTnI and 1 cTnT) in patients with ACS. METHODS: This study was carried out between October 2001 and June 2002 at Armed Forces Hospital in collaboration with Prince Sultan Cardiac Center, Riyadh, Kingdom of Saudi Arabia. Blood samples from 96 patients, 40 with and 56 without clinical evidence of myocardial injury, were used for the evaluation. Cardiac TnI assays were performed using 5 different immunoanalyzers AxSYM (Abbott Laboratories), Stratus CS (Dade Behring), ACS:180 (Bayer), Centaur (Bayer) and Immulite (Diagnostic Products Corporation) while cTnT was measured on the Elecsys (Roche) immunoanalyzer. The sensitivity, specificity and positive and negative predictive values (PV) were calculated for all assays. General and special features related to installation, routine operation, quality control and other various special parameters of each immunoanalyzer were evaluated (using the score of 1-5 for each parameter) and compared with those of other analyzers. RESULTS: The highest reliability values were observed with Immulite, followed by AxSYM, then Stratus, then ACS:180, and Centaur, and lastly by Elecsys. The highest practicability values were observed with Elecsys, and Centaur, followed by AxSYM and the lowest values were observed with Stratus. CONCLUSION: Considering the combined performance and practicability score, the difference between the 10% coefficient variation cut off value and the 99th percentile value, and the difference in the relative reactivities to the various cTnI forms, the most favorable values were observed with AxSYM, followed by Immulite and Elecsys, then Centaur and Stratus, and lastly by ACS:180.

Percutaneous coronary intervention in the context of systemic inflammation: more injury and worse outcome.

Minor myocardial injury (MMI), identified by elevated serum levels of cardiac markers, is not uncommon after successful, uncomplicated elective percutaneous coronary intervention (PCI) in patients with stable angina. Serum cardiac troponin, especially cardiac troponin I (cTnI), are more sensitive than serum creatine kinase - MB in detecting MMI. Occlusion of small side-branch vessels, visualized by angiography, may explain the mechanism of the MMI in some, but not all patients. Occlusion of small intramyocardial vessels, not visualized by angiography, might be the mechanism of MMI in these patients. Recent reports have shown that cardiac troponin I elevation after successful, uncomplicated elective PCI in patients with stable angina may be a marker of adverse long-term outcome. Also, it has recently been reported that increased serum C-Reactive protein (CRP) is common in patients with stable angina and is a significant and independent determinant of MMI after uncomplicated elective PCI, indicating involvement of the systemic inflammatory state in the etiology of this periprocedural myocardial injury. An intense inflammatory response is expected following PCI in patients with increased baseline CRP levels, which can cause small vessel occlusion and/or microembolization that will lead to troponin elevation. With these findings in mind, and with the observation that increased risk associated with systemic inflammation can be reduced with certain preventive therapies, CRP may help to identify those who would benefit most from these pharmacological therapies before coronary interventions.

Biochemical detection of minor myocardial injury after elective, uncomplicated, successful percutaneous coronary intervention in patients with stable angina: clinical outcome.

BACKGROUND: Minor elevations of creatine kinase MB isoform (CK-MB) identified a population with a worse long-term prognosis after successful coronary intervention. Recent studies provide evidence that cardiac troponin I (cTnI) is more sensitive than CK-MB for the detection of minor myocardial injury after coronary intervention. The purpose of the study was to determine the prognostic value of cTnI elevation after elective uncomplicated successful percutaneous coronary intervention (PCI). METHODS: cTnI was measured in 96 patients with stable angina before and 24 h after elective uncomplicated successful percutaneous transluminal coronary angioplasty (PTCA) with or without stenting. Patients were followed up for adverse cardiac events (recurrent angina, non-fatal myocardial infarction, cardiac death, repeat PCI or coronary bypass surgery). Procedure success was achieved in all cases. RESULTS: Cardiac events were best predicted by cTnI when a cut-off value of 2.0 microg/L was used. Abnormal cTnI values at 24 h after PCI were observed in 26 patients (27%). Over a follow-up period of 24 months with no significant difference in the medication used, the incidence of recurrent angina, repeat PCI, coronary bypass surgery and cardiac death was 54%, 46%, 4% and 4%, respectively, in the cTnI-positive patients versus 27%, 16%, 4% and 0% in the cTnI-negative patients. Kaplan-Meier survival analysis showed that cTnI elevation was a significant correlate of cardiac events (P = 0.0198, by log rank analysis). CONCLUSIONS: Elevation of cTnI is not uncommon after elective uncomplicated successful PCI in patients with stable angina and this elevation might be a marker of adverse long-term outcome.

Markers of inflammation and coronary artery disease.

Many recent experimental and clinical studies have provided evidence for the presence of inflammation in atherosclerotic lesions. Ongoing inflammatory reactions within coronary atherosclerotic plaques are increasingly thought to be crucial determinants of the clinical course of patients with coronary artery disease (CAD). These facts lead to a search for reliable markers reflecting the inflammatory process in the atherosclerotic plaques. Circulating markers may consist of cytokines directly released from inflammatory cells present in the plaques and tissues exposed to recurrent ischemia as well as other reactants produced in response to these cytokines such as adhesion molecules and acute phase proteins. Recent studies suggest that markers of inflammation may reflect different aspects of the atherothrombotic process at different points in the continuum of acute coronary syndromes, have a potential role for the prediction of risk for developing CAD, and may correlate with severity and future risk for CAD. In spite of these findings, the clinical utility of measuring these markers is limited by the availability of reproducible diagnostic test assays. In addition, it remains to be determined whether markers of inflammation actually have a causal relation with cardiovascular disease, or simply reflect the underlying disease process. Such determination becomes important with the potential use of these markers in targeting preventive therapies. Therefore, further well-designed prospective evaluation of each of these markers is needed before their use in routine practice.