Release Characteristics of Cardiac Biomarkers and Ischemia-modified Albumin as Measured by the Albumin Cobalt-binding Test after a Marathon Race

Abstract

Numerous studies have monitored the appearance of both cardiac and skeletal muscle proteins and enzymes after short- and long-term exercise regimens. Both animal and human exercise models have attempted to determine whether the stress of long-duration exercise, such as a marathon race (42.2 km), could cause myocardial necrosis and the release of cardiac-specific proteins, such as cardiac troponin I (cTnI) or T (cTnT) (1)(2)(3)(4). In a rat animal model, the severe stress of swimming for 5 h caused microscopic evidence of myocardial necrosis, which led to substantially increased serum cTnT concentrations (1). However, in a less stressful regimen of 1–3 h of swimming, no evidence of ischemic injury and only very minor alterations in serum cTnT concentrations were detected. Middle-aged male marathon runners had increases in inflammatory and prothrombotic markers within 4 h after completion of a race (5). Increases in cTnI were also observed (6). However, no evidence of microinfarction was found by sestamibi imaging, nor was evidence of left ventricular dysfunction found by B-natriuretic peptide testing (6). Ischemia-modified albumin (IMA), measured by the albumin cobalt-binding (ACB) test (7), is reported to predict subsequent cTnI results for patients presenting with symptoms of acute coronary syndromes. Furthermore, studies that included percutaneous transluminal coronary angioplasty as a model of transient myocardial ischemia have demonstrated that serum IMA concentrations, as measured by the ACB test, were increased very early after an ischemic event (8); thus, IMA may be a very early indicator of myocardial ischemia before necrosis. To test this hypothesis in healthy persons at very low risk for cardiac disease but at high risk for skeletal muscle damage, we studied the appearance and clearance characteristics of the IMA marker compared with cTnI, cTnT, and myoglobin in runners after a marathon race. Nineteen Caucasian runners, …