Background: The diagnostic approach and the clinical management of patients presenting with suspected acute coronary syndrome or cardiac dysfunction are as yet challenging. Although ischemia modified albumin (IMA) and natriuretic peptides were recently proposed for detection of myocardial ischemia and cardiac dysfunction, little information is available on preanalytical and metabolic sources of variability of these markers.
Methods: To establish the influence of a regular endurance training and the relationship with conventional biochemical variables, NT-pro-brain natriuretic peptide (NT-proBNP) and IMA were assayed, along with cardiac troponin T (cTnT), lactate dehydrogenase (LDH), creatine kinase (CK), creatinine and albumin, in 35 sedentary healthy individuals and 50 male professional road cyclists, 12-24 h following the last demanding training session.
Results: Athletes displayed higher values of both LDH (299+/-61 vs. 257+/-36 U/l, P=0.002) and CK (184+/-123 vs. 115+/-74 U/l, P=0.011), and slightly lower concentrations of creatinine (82+/-12 vs. 87+/-9 micromol/l, P=0.044). No athlete or sedentary control displayed cTnT concentrations exceeding the lower sensitivity limit of the assay. As compared to the sedentary controls, main IMA concentration was increased in athletes (100+/-13 vs. 94+/-6 KU/l, P=0.035), whereas that of NT-proBNP appeared significantly decreased (2.8+/-1.6 vs. 4.3+/-34, P=0.005). The percentage of subjects displaying values exceeding the upper reference limit for the IMA assay was significantly different between athletes and sedentary controls (50% vs. 7%; P<0.001). Pearson correlation analysis revealed an inverse association between IMA and albumin in both athletes (r=-0.640; P<0.001) and sedentary controls (r=-0.583; P=0.001).
Conclusions: Results of our investigation indicate that a demanding and regular aerobic training regimen, though able to trigger skeletal muscle sufferance, is not associated with any biochemical sign of severe and irreversible chronic cardiac involvement. Moreover, we suggest the adoption of specific IMA diagnostic thresholds following patients' stratification according to serum albumin concentration and physical activity.