Cardiac troponin: Caveats and controversies in analysis and interpretation

PURPOSE: To review the caveats and controversies in the interpretation of elevated cardiac troponin (cTn) serum levels as related to European Society of Cardiology/American College of Cardiology recommendations for diagnosis of acute myocardial infarction (MI). EPIDEMIOLOGY: Several million patients seek emergency care as a result of chest pain, but only about 10% are subsequently confirmed to have acute MI. The number or patients diagnosed with MI may increase from 40% to 80% according to the setting of the cTn test performed and the details of the assays used. REVIEW SUMMARY: Despite extensive use and validity of cTn in diagnosis of myocardial necrosis, the determinants of cTn release and the patterns of elevation and clearance are subjects of controversy. Other confounding factors are lack of standardization of biomarker assays and disagreement over what constitutes normal vs abnormal results. False-positive results may occur among earlier-generation assays due to cross-reactivity with a variety of other proteins. Finally, elevated cardiac biomarkers secondary to myocardial necrosis do not necessarily equate to acute MI. TYPE OF AVAILABLE EVIDENCE: Systematic reviews/meta-analyses, cohort studies (prospective and retrospective), case-control studies, unstructured reviews. GRADE OF AVAILABLE EVIDENCE: Fair. CONCLUSION: Although cTn serum levels have diagnostic and prognostic implications, clinical assessment of the patient remains essential to any diagnosis. The cTn level should be used as an assistant to-not a replacement for-informed clinical decision making. Primary care clinicians should know the details of the assays used at their medical institutions.