The renin-angiotensin--aldosterone system and the clinical course of acute myocardial infarction.

To determine whether the renin--angiotensin--aldosterone system is stimulated in myocardial infarction, plasma renin activity and serum aldosterone were measured by radioimmunoassay in 95 patients with acute infarction. Urinary catecholamines, and sodium and potassium levels in blood and urine were also determined. Plasma renin activity and aldosterone were insignificantly increased in mild myocardial infarction as compared to a reference group comprising patients with angina pectoris. In patients with a complicated course, however, they were greatly augmented. A close correlation was found between urine catecholamines and plasma renin activity and between urine noradrenaline and aldosterone. Aldosterone values were highly correlated with the urine potassium/sodium ratio.