COMPARISON OF SECRETION PATTERN BETWEEN A-TYPE AND B-TYPE NATRIURETIC PEPTIDES IN PATIENTS WITH OLD MYOCARDIAL-INFARCTION

Objectives. The present study was designed to compare the secretion patterns of two cardiac hormones-A-type (atrial) and B-type (brain) natriuretic peptides-from the ventricles in patients with old myocardial infarction. Background. Plasma levels of these two natriuretic peptides are increased, and their secretion from the ventricles is augmented, in patients with congestive heart failure. Methods. We measured the plasma levels of these two types of natriuretic peptides at the aortic root and the anterior interventricular vein in 42 patients with old myocardial infarction (anterior in 22 and inferior in 20) and 18 control subjects. Results. The difference between the plasma levels of both A- and B-type natriuretic peptide in the anterior interventricular vein and aortic root was significantly greater in the groups with anterior and inferior infarction than in the control group (A-type [mean +/- SD] 380 +/- 290 and 247 +/- 205 pg/ml in the infarction groups vs. 11 +/- 14 pg/ml; B-type 497 +/- 445 and 75 +/- 73 pg/ml vs. 23 +/- 16 pg/ml, respectively). The difference between the plasma levels of each peptide at the anterior interventricular vein and aortic root had a significant negative linear correlation with left ventricular ejection fraction in both groups with infarction. The slope of the regression line of the arteriovenous difference of B-type natriuretic peptide at the anterior interventricular vein was significantly steeper in the anterior than in the inferior infarction group (left ventricular ejection fraction -12.801 vs. -1.891, p < 0.01). Conclusions. These results indicate that 1) the secretion of A- and B-type natriuretic peptide from the left ventricle increases in proportion to the severity of left ventricular dysfunction, and 2) secretion of B-type natriuretic peptide is much greater from the infarct than from the noninfarct region, suggesting,that the regional ventricular wall stretch caused by infarction strongly stimulates secretion of B-type natriuretic peptide.