Background: The European Society of Cardiology and American College of Cardiology guidelines for redefinition of myocardial infarction suggest that the cutoff value for diagnosis of acute myocardial infarction (AMI) be the 99th percentile of the reference population at a level measured with imprecision (coefficient of variation) > or =10%. No current commercially available troponin assay meets this requirement. Accordingly, questions have been raised about how to implement cutoff values from the guidelines. The Clinical Outcomes Utilizing Revascularization and Aggressive druG Evaluation (COURAGE) trial asked for recommendations concerning the use of troponin assays for the trial.
Methods: Cutoff values for the various assays were obtained from package inserts or from direct communication with manufacturers.
Results: The cutoff value with > or =10% imprecision was above the 99th percentile of the reference range for all assays. For the present, we suggest that this value be used for clinical and clinical trial purposes. It will account for analytic variability and individual biological changes. We provide recommendations for clinical practice and clinical trials concerning how to make the diagnosis of AMI in patients with ischemic symptoms and patients who undergo percutaneous coronary intervention and coronary artery bypass surgery.
Conclusions: This is a first attempt to define cutoff values on the basis of the European Society of Cardiology and American College of Cardiology guidelines. These criteria will provide increased consistency until assays improve to allow full implementation of the guidelines.