Plasma vasoactive peptides after acute myocardial infarction in relation to left ventricular dysfunction.

We measured plasma concentrations of vasoactive peptides in 32 patients with acute myocardial infarction and evaluated their value as markers of left ventricular dysfunction. Plasma levels of atrial natriuretic peptide (ANP), the N-terminal fragment of proANP (NT-proANP), B-type natriuretic peptide (BNP) and endothelin-1 were measured serially by radioimmunoassays. The infarct size was estimated from the creatine kinase MB release curve. Coronary angiography and left ventricular cineangiography were performed in all patients during hospitalization and 6 months later in 15 patients. Myocardial infarction caused an increase in vasoactive peptides, the highest values for ANP (36.5+/-6.79 pmol/l), NT-proANP (1130+/-170 pmol/l) and endothelin-1 (9.72+/-0.68 pmol/l) being found on admission and those for BNP (56.0+/-7.13 pmol/l) on Day 2. Plasma levels of natriuretic peptides were dependent on infarct size, its location and degree of myocardial dysfunction and that of BNP also on infarct artery patency. Plasma endothelin-1 level was higher in patients with TIMI 3 than TIMI 0-2 flow. Plasma vasoactive peptides remained elevated during the 6-month follow-up period and they were dependent on the degree of myocardial dysfunction. BNP measured on any day of hospitalization showed the best correlation with ejection fraction measured during the acute phase of infarction or at 6 months. The results show that BNP is the best indicator of left ventricular dysfunction after myocardial infarction and its reliability is not dependent on the time point of measurement.