Optimizing the Use of Biomarkers in the ER

Cardiac biomarkers have emerged as reliable tools to identify bedside myocardial necrosis, ventricular failure, and endogenous fibrinolysis activation, improving the outcome of thousands of patients around the world presenting in the emergency room (ER). However, any biomarker should not be used as a stand-alone test for diagnosis of cardiovascular disease. Although there have been enormous advances in their analytical features increasing clinical operating characteristics, we are still far from the ideal biomarker. Furthermore, any physician should be familiar with the concepts of clinical sensitivity and specificity, as well as predictive values and likelihood ratios. Physicians in charge will be able to request a test, interpret the results, and deliberate their meaning for clinical decision-making in an appropriate manner. The severity of the potential consequences relates to the test being performed, the extent of the difference between the reported result and the true result, as well as the ability of clinicians to recognize the issues related to biomarker testing. During this chapter, we will discuss the basic principles for the proper use of biomarkers, physiology, analytical features, clinical relevance, and challenges and limitations of high-sensitivity cardiac troponins, natriuretic peptides, and D-dimer in the ER. Also, we will address the concepts of predictive values and likelihood ratios as the essential concepts of Bayesian reasoning and its application for the benefit of our patients.