The present study was designed to clarify whether
osteopontin, an
extracellular matrix protein, is released from the heart into the coronary circulation in patients with a previous (>3 months)
anterior wall myocardial infarction (MI). Using a commercially available
enzyme immunoassay kit, plasma concentrations of
osteopontin were measured in 30 patients (26 men, 4 women; mean age, 61+/-12 years). Blood samples were obtained from the aortic root and coronary sinus. The difference in the plasma concentrations of
osteopontin in the aortic root and coronary sinus, which reflects the cardiac production of
osteopontin released into the coronary circulation, was compared with the left ventricular ejection fraction (LVEF) and volumes obtained from contrast left ventriculography. Plasma
osteopontin concentrations were significantly higher in the coronary sinus than in the aortic root (672+/-446 vs 610+/-398 ng/ml, p=0.02). The transcardiac gradient of plasma
osteopontin concentration correlated negatively with LVEF (r=-0.55, p=0.0005) and positively with left ventricular (LV) end-diastolic (r=0.63, p=0.0001) and end-systolic volume indexes (r=0.79, p<0.0001). This is the first study to show that in patients with a previous anterior wall MI
osteopontin is released from the heart into the coronary circulation in proportion to the LV systolic function and volumes, suggesting that this extramatrix
protein is associated with post-MI LV remodeling.