[Atrial natriuretic factor and brain natriuretic peptide. Variations in elderly subjects with heart failure]

Atrial natriuretic factor (ANF) is a peptide hormone secreted by the atria in response to increased transmural pressure. This peptide is the first of a series of natriuretic hormones which also includes brain natriuretic peptide (BNP). It is destroyed mainly by an ubiquitous enzyme, neutral endopeptidase (NEP). Its main actions are vasodilatation and natriuresis. It is the main physiological agonist of the renin/angiotensin/aldosterone system. In elderly subjects free of cardiovascular disease, baseline concentrations are higher than in younger subjects. In patients with congestive heart disease (CHD), the level of ANF rises due to permanent increased filling pressures. Both atrial and ventricular secretion increase ANF levels which loose their day/night rhythm. ANF is a risk factor independent of mortality, rhythm disorders and acute heart failure in patients with heart failure. BNP is also raised in CHD. There is an inverse correlation between concentration and severity of left ventricule dysfunction. There has been little work on ANF in elderly subjects with CHD. ANF is elevated in these patients and is an independent risk factor for cardiac decompensation. In addition, in very elderly subjects where the diagnosis of CHD is difficult and echocardiography not always possible, assay of BNP could be an interesting diagnostic tool. Currently work on therapeutic possibilities (administration of exogenous ANF, combinations with NEP inhibitor/conversion enzyme inhibitor, ANF/diuretics) have revealed certain problems (short half life of ANF, transient effects, non-specific activity of NEP). The usefulness of ANF and BNP in heart failure in elderly subjects will undoubtedly lie in its capacity to mark disease severity and as a diagnostic tool, particularly in case of acute dyspnoea.