SELECTIVE ACTIVATION OF ATRIAL-NATRIURETIC-PEPTIDE IN PATIENTS WITH MYOCARDIAL-INFARCTION AND MILD LEFT-VENTRICULAR DYSFUNCTION

The purpose of this study was to investigate whether neurohumoral acti vation occurs in asymptomatic patients with acute myocardial infarctio n (AMI) and without clinical signs of heart failure. During the early phase of AMI (mean 8 days), the neurohumoral profiles of 60 patients ( mean age 59 range 37 to 70) were examined. Blood levels of the followi ng humoral parameters were measured: atrial natriuretic peptide (ANP), plasma renin activity, aldosterone and vasopressin. All patients unde rwent cardiac catheterization during hospitalization. Baseline hemodyn amic characteristics identified left ventricular dysfunction (ejection fraction less-than-or-equal-to 45%) and/or left ventricular end-diast olic pressure greater-than-or-equal-to 15 mmHg) in 32 patients; the re maining 28 patients had normal hemodynamic parameters. In patients wit h AMI, plasma ANP levels differed significantly from control subjects (111 +/- 74 pg/ml vs. 53 +/- 18 pg/ml; P < 0.001). In patients with AM I and mild left ventricular dysfunction ANP levels were significantly increased when compared to patients with AMI and normal left ventricul ar function (129 +/- 73 pg/ml vs. 82 +/- 69 pg/ml; P < 0.001). The hem odynamic data showed a significant correlation with ANP only in patien ts with AMI and left ventricular dysfunction (EF% r = 0.42; LVEDP r = 0.44; P < 0.001). These data show that in patients with myocardial inf arction and without heart failure, the atrial natriuretic peptide is t he only neurohumoral system activated out of all neurohumoral systems tested in this population and its circulating levels are strictly rela ted to the degree of left ventricular dysfunction.