PLASMA BRAIN NATRIURETIC PEPTIDE AS AN INDICATOR FOR ANGIOTENSIN-CONVERTING-ENZYME INHIBITION AFTER MYOCARDIAL-INFARCTION

Brain natriuretic peptide (BNP) is a cardiac ventricular hormone that may be a sensitive and specific marker of changes in ventricular funct ion. In a prospective, randomised open trial with 16 patients followed for 6 months after first Q wave anterior myocardial infarction we set out to determine: whether BNP concentrations are raised acutely, the effect on circulating BNP of angiotensin-converting enzyme (ACE) inhib ition, how BNP and atrial natriuretic peptide (ANP) concentrations com pared as correlates of left-ventricular ejection fraction, and whether plasma BNP concentrations could distinguish patients with low (<40%) and relatively preserved (>40%) ejection fractions. Plasma concentrati ons of BNP measured on days 2, 7, 8, 42, and 180 postinfarction were s ignificantly raised in patients compared with normal controls and to a proportionately greater degree than ANP concentrations. Treatment wit h placebo (n=8) or oral captopril (n=8) from day 8 resulted in signifi cantly lower BNP concentrations at days 42 (p=0.05) and 180 (p<0.05) i n the captopril-treated group. Compared with ANP, BNP concentrations w ere much more strongly correlated with radionuclide-measured left-vent ricular ejection fraction at days 2, 42, and 180. All 8 patients with baseline (day 2) ejection fractions of 40% or above had plasma BNP con centrations less than 10 pmol/L, whereas the 8 patients with ejection fractions less than 40% had BNP concentrations greater than 10 pmol/L. Our findings suggest that measurements of circulating BNP may identif y those patients with significant left-ventricular dysfunction who hav e been highlighted by the Survival and Ventricular Enlargement study a s likely to benefit from long-term ACE inhibition after myocardial inf arction.