Les nouveaux marqueurs biologiques de cardiologie (peptide natriurétique de type B et troponine) : intérêt en réanimation

Abstract

Research for "ideal" biological diagnostic markers able to also assess patient severity and to guide treatment, is a hallmark of modern medicine, especially in ICU. Brain natriuretic peptide and troponin are two cardiac biological markers that have been measured and studied in different ICU pathologies. Development of rapid, accurate and affordable diagnostic methods allows the routine monitoring of these two proteins in a wide spectrum of ICU settings, summarized in this review. B-type natriuretic peptide (BNP), a neurohormone synthesized in the cardiac ventricles, is released upon ventricular myocyte stretch. Blood measurements of BNP have been initially demonstrated to be useful to detect left-ventricular systolic dysfunction and to determine the etiology of dyspnea. Impressive accumulation of recent data highlights the value of BNP plasma levels in a variety of other ICU situations (diastolic cardiac dysfunction, right ventricular failure such as pulmonary embolism and severe sepsis) supporting an important role of BNP as a diagnostic and prognostic marker and to guide therapy. Finally, physiological properties of this natriuretic peptide may be used to treat heart failure through recombinant human BNP and vasopeptidase inhibitors. Measurement of cardiac troponin levels constitute the gold standard to assess ischemic heart disease from silent ischemia to acute myocardial infarction. Elevated troponin has also been shown to be a mortality risk factor for medical intensive care patients admitted for reasons other than acute coronary syndromes. The clinical application of cardiac biomarkers in ICU is no longer limited to establishing or refuting the diagnosis of myocardial failure or necrosis. BNP and troponin are specific diagnostic and prognostic markers that may provide convenient and noninvasive means to assess mortality risk of severe patients. They may be targets for specific therapeutic interventions. A multimarker paradigm using a combination of both established and new markers for risk assessment and clinical decision-making has the potential to improve substantially the outcome in ICU patients.