INFLUENCE OF ANGIOTENSIN-CONVERTING ENZYME-INHIBITION ON RELATION OF ATRIAL-NATRIURETIC-PEPTIDE CONCENTRATION TO ATRIAL PRESSURE IN HEART-FAILURE

Objective-To examine the relation between haemodynamics and atrial nat riuretic peptide concentration during short term angiotensin convertin g enzyme inhibition. Design-Patients were randomly allocated to receiv e placebo or one of three doses of the angiotensin converting enzyme i nhibitor ramipril. Setting-Cardiac units of two tertiary referral hosp itals. Subjects-38 Patients with stable congestive heart failure cause d by ischaemic heart disease. Methods-Data were collected over a 24 ho ur period and assessed with the aim of distinguishing between the haem odynamic effects on plasma concentrations of atrial natriuretic peptid e and the direct effects of the study drug, vasopressin concentrations , and angiotensin converting enzyme activity. Results-Pulmonary capill ary wedge pressure was the main predictor of the plasma concentration of atrial natriuretic peptide. A higher plasma concentration of this p eptide with a given pulmonary capillary wedge pressure was found after 24 hours of treatment with 2.5 mg and 5 mg of ramipril. Plasma concen tration of the active metabolite, change in arginine vasopressin conce ntration or degree of angiotensin converting enzyme inhibition did not significantly predict change in plasma concentration of atrial natriu retic peptide or in the ratio of atrial natriuretic peptide concentrat ion to pulmonary capillary wedge pressure. Conclusions-A gradual incre ase in plasma concentration of atrial natriuretic peptide with a given pulmonary capillary wedge pressure, occurs during short term high deg ree inhibition of angiotensin converting enzyme. The causative mechani sms are yet to be identified. Such a change in the relation between ce ntral haemodynamics and atrial natriuretic peptide concentration may c ontribute to the beneficial effects of angiotensin converting enzyme i nhibition in patients with congestive heart failure due to ischaemic h eart disease.