20 Aug Clinical Chemistry Score Helps Rule Out Diagnosis of Heart Attack
MedicalResearch.com Interview with:
Peter Kavsak, PhD, FCACB, FAACC, FCCS
Professor, Pathology and Molecular Medicine
MedicalResearch.com: What is the background for this study?
Response: For patients who present to the hospital with symptoms suggestive of acute coronary syndrome (ACS) the preferred blood test to help physicians in making a diagnosis is cardiac troponin.
Recent studies have demonstrated that a very low or undetectable cardiac troponin level when measured with the newest generation of blood tests (i.e., the high-sensitivity cardiac troponin tests) in this population may rule-out myocardial infarction (MI or a heart attack) on the initial blood sample collected in the emergency department, thus enabling a faster decision and foregoing the need for subsequent serial measurements of cardiac troponin over several hours as recommended by the guidelines. The problem with this approach, however, is that using high-sensitivity cardiac troponin alone to do this has not reliably been demonstrated to achieve a sensitivity >99% for detecting MI, which is the estimate that most physicians in this setting consider as safe for discharge.
Our study goal was to compare the diagnostic performance of a simple laboratory algorithm using common blood tests (i.e., a clinical chemistry score (CCS) consisting of glucose, estimated glomerular filtration rate (eGFR), and either high-sensitivity cardiac troponin I or T) to high-sensitivity cardiac troponin alone for predicting MI or death within the first month following the initial blood work.
MedicalResearch.com: What are the main findings?
Response: In 4245 patients with symptoms suggestive of ACS and without ST-elevated MI, from emergency department studies from Australia, Canada, Germany and New Zealand, 727 patients either had a MI or died (primary outcome) within 30 days of the initial blood draw.
A CCS of 0 (low-risk score), which consisted of normal values of glucose, eGFR and high-sensitivity cardiac troponin, achieved a sensitivity ≥99.9% as compared to a sensitivity ≤98.2% when using high-sensitivity cardiac troponin alone for the primary outcome. A CCS of 5 (high-risk score), which consisted of all abnormal values for glucose, eGFR and high-sensitivity cardiac troponin achieved a specificity ≥94.0% for the primary outcome as compared to a specificity ≤93.2% when using high-sensitivity cardiac troponin alone.
MedicalResearch.com: What should readers take away from your report?
Response: Incorporating glucose and eGFR, which both have independent prognostic roles in this setting, with high-sensitivity cardiac troponin testing to form the CCS outperforms high-sensitivity cardiac troponin alone for the primary outcome in this study, as well as for several secondary outcomes including index MI diagnosis, 30-day unstable angina, MI and death as well as providing important prognostic information on the revascularization rate.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: A prospective study of the CCS to evaluate its clinical effectiveness in patients presenting with symptoms suggestive of ACS to the emergency department would be beneficial. Also, evaluation of the CCS in both secondary and primary prevention of cardiovascular disease would also be of interest.
MedicalResearch.com: Is there anything else you would like to add?
Response: The CCS includes concentration cut-off values for high-sensitivity cardiac troponin which are measurable and thus can be monitored on a regular basis by the clinical laboratory. Thus, all variables in the CCS can be monitored via quality assurance procedures in the clinical laboratory thereby enabling more precise and accurate laboratory testing for physicians in this setting. Please refer to the CMAJ paper for the specific cut-off values in the CCS and for competing interests listed by the Authors.
Clinical chemistry score versus high-sensitivity cardiac troponin I and T tests alone to identify patients at low or high risk for myocardial infarction or death at presentation to the emergency department
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