Cardiac Biomarkers in Renal Disease: The Fog is Slowly Lifting (Editorials‪)‬

It has long been known that among patients with end-stage renal disease (ESRD), cardiac disease is the single greatest cause of mortality, accounting for nearly one half of all deaths (1). Among community-based populations, renal insufficiency is an independent predictor of the risk of subsequent ischemic heart disease, conferring a risk equivalent to that of diabetes (2). Furthermore, the presence of even moderate renal impairment in a patient presenting with an acute coronary syndrome (ACS) is a strong short-term prognostic indicator, significantly increasing the 30-day risk of myocardial infarction, heart failure, and cardiac death (3). Thus, a strong and pervasive link clearly exists between kidney failure and cardiac disease. The common challenge to the nephrologist, cardiologist, and emergency physician therefore lies in successfully recognizing those patients within their scope of practice who are most at risk, thereby allowing targeted application of interventions designed to circumvent adverse outcomes. Accordingly, there is an exigent need for the clinical laboratory to identify and make available reliable assays for biomarkers that can predict adverse events across a range of clinical settings and among patients with various degrees of kidney dysfunction, as well as to elucidate the performance characteristics and limitations of each of these markers. A variety of individual biomarkers have previously been evaluated for this purpose, and several have been found to successfully predict outcome in patients with kidney disease. These include markers of myocardial necrosis, such as cardiac troponin T (cTnT) and I (cTnI) (4); markers of heart failure, such as B-type natriuretic peptide (BNP) and its associated inactive N-terminal fragment (NT-proBNP) (5); and the marker of systemic inflammation, high-sensitivity C-reactive protein (hsCRP) (6). However, fulfillment of the obvious potential of these biomarkers to have a positive impact on the care of renal failure patients has been elusive because of unresolved clinical concerns that have caused application of these markers in this critical patient subgroup to lag behind their otherwise rapid integration in a broad spectrum of practice settings. In fact, it is fair to say that the short history of cardiac biomarker use among renal failure patients to date has been mostly characterized by controversy among scientists and confusion among clinicians.