Plasma brain natriuretic peptide correlates with infarct size but not with subsequent remodeling in the rat heart

Abstract

Brain natriuretic peptide is a marker of the severity of congestive heart failure. However, the relation between its concentration and ventricular remodeling after myocardial infarction remains unknown. Thus, we studied plasma brain natriuretic peptide over 6 months after myocardial infarction in the rat and correlated it with parameters of left ventricular remodeling. Myocardial infarction was induced in 152 male Wistar rats by left coronary artery ligation. Rats were followed up for 1 week, 1 month, 3 months, or 6 months after myocardial infarction. Then left ventricular end-diastolic volume and maximal systolic pressure were assessed in the isolated heart, heart and lung weights were obtained, wall stress was calculated, cardiomyocyte size was measured, and plasma brain natriuretic peptide was assessed with enzyme-linked immunosorbent assay. Large (> or =40%) but not small/intermediate infarcts were accompanied by progressive ventricular dilation and increase in wall stress, left ventricular weight, and lung weight, while systolic pressure, which was already depressed 1 week after myocardial infarction, did not show progression over time. Plasma brain natriuretic peptide reached its peak on Day 3 after myocardial infarction and did not progress any further; it correlated with infarct size and the extent of left ventricular dilation. Thus, after a large myocardial infarction in the rat, despite progressive left ventricular dilation and increase in wall stress, plasma brain natriuretic peptide did not progress over time. This indicates that, although plasma brain natriuretic peptide is a good indicator of infarct size and left ventricular dilation, it cannot be used to trace progressive ventricular remodeling in the rat heart after myocardial infarction.