Myocardial injury-related changes in plasma NT-proBNP and ANP concentrations in a canine model of ischemic myocardial injury

Serial changes in plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) and atrial natriuretic peptide (ANP) concentrations are unknown in dogs with myocardial injury. The time-course secretory responses between NT-proBNP and ANP or cardiac troponin-T (cTnT) related to myocardial infarction (MI) were investigated in this study. Six dogs were anaesthetised and the left anterior descending artery was ligated. A transient decrease in cardiac function was detected 1h after MI but returned to baseline levels within 7 days and remained so for 6 months. Echocardiographic examination revealed focal ventricular dyskinesis throughout the study. Six months following MI, the left atrium to aorta ratio increased significantly although the relative wall thickness decreased significantly from baseline. Significantly elevated plasma NT-proBNP and cTnT concentrations were detected 1 day after MI and these gradually decreased over 28 days to baseline levels without left ventricular pressure elevation. Plasma ANP was elevated significantly 6 months after MI. The NT-proBNP assay is a helpful diagnostic indicator for identifying asymptomatic acute and subacute myocardial injury whereas plasma ANP concentration mainly reflects atrial dilation.