New Biomarkers of Ischemia

The traditional biomarkers, CK-MB and troponins, used for the diagnosis of myocardial ischemia and the risk stratification of patients with acute coronary syndromes (ACS) are of limited use mainly because they require some degree of necrosis in order to become detectable. Based on the knowledge gained into the pathophysiology of ACS, several new biomarkers have been developed. Brain natriuretic peptides (BNP and NT-proBNP) as markers of hemodynamic stress have shown in several studies a good diagnostic and prognostic performance. C-reactive protein (CRP) reflecting systemic inflammation, has mainly a role as risk stratifier. Ischemia modified albumin (IMA) a pure ischemia marker may offer a substantial aid in diagnosing an acute coronary event in patients with negative troponin. Finally, myeloperoxidase (MPO), a marker of oxidative stress, may also contribute to the diagnosis of ischemia although this is not yet supported by a fair amount of data. Nevertheless, although highly sensitive, these new biomarkers are not specific enough and a multi-marker approach seems the most appropriate strategy for diagnosis of myocardial ischemia and for assessing the risk of an adverse outcome in patients with an acute coronary syndrome. I N T R O D U C T I O N Establishing a diagnosis of myocardial ischemia in the clinical setting remains a challenging task. In addition to history of chest pain and abnormal electrocardiographic (ECG) changes, laboratory evidence of myonecrosis has always been an integral part of the initial diagnostic work up of a suspected acute coronary syndrome (ACS) [1]. Unfortunately, the myonecrosis markers, myoglobin, creatine kinase (CK-MB) and the troponins (Tns), cannot by definition help clinicians in the assessment of patients with stable or unstable angina where ischemia is not accompanied most of the time by myocardial necrosis. In addition, myocardial necrosis is time-dependent, such that these highly sensitive and specific markers might give negative results on admission but give positive results hours later [2]. As such, the usefulness of the conventional biomarkers of myocardial necrosis for the confident exclusion of the diagnosis of myocardial ischemia at the time of admission remains limited. Markers able to identify CARDIOLOGY UPDATE 2006 1st Department of Cardiology, Evagelismos General Hospital of