Insufficient secretion of atrial natriuretic peptide at acute phase of myocardial infarction

To investigate the secretion of the plasma levels of atrial natriuretic pep tide (ANP) in patients with acute myocardial infarction (AMI), we evaluated the relationship between plasma levels of ANP and pulmonary capillary wedg e pressure (PCWP) in 45 consecutive patients during the acute phase of AMI (similar to 12 h after the attack) (group 1) and compared data with those o btained after 1 mo (group 2). In both groups 1 and 2, plasma ANP levels sig nificantly correlated with PCWP. The slope of the linear regression line be tween the PCWP and ANP in group 1 was significantly lower, by about one-thi rd, than that in group 2. In addition, we examined changes in ANP levels an d left ventricular end-diastolic pressure (LVEDP) over 180 min after AMI in duced by injection of microspheres into the left coronary arteries of three dogs. The LVEDP and ANP levels 30 min after AMI were significantly higher than those before; however, despite the persistent high LVEDP during the 18 0 min after AMI, ANP levels decreased gradually and significantly to 63% of the peak level at 150 min. These findings suggest that the secretion of AN P during the acute phase of myocardial infarction may be insufficient relat ive to the chronic phase.