B-type natriuretic peptide assays for detecting heart failure in the elderly: same value as those in the younger?

Abstract

Establishing a diagnosis of heart failure in elderly patients is notoriously difficult, especially in those who experience slowly progressive breathlessness, have multiple co-morbidity, and when, as in primary care echocardiography is not routinely (or readily) available. B-type natriuretic peptides measurements are useful in the diagnostic assessment of such patients, although the evidence in the very old (i.e. those aged 75 years and over) is less clear than for younger patients. Conflicting results in literature regarding B-type natriuretic peptides are mainly caused by differences in assays, the applied 'gold standard' for heart failure, and the population studied. Moreover, there is no consensus as to whether similar cut-off points should be applied across age-groups. Numerous studies showed that plasma levels of B-type natriuretic peptide are elevated in the elderly, including the 'healthy' ones. Age-related myocardial fibrosis and subtle diastolic dysfunction that are not detectable by current techniques, and reduced renal clearance have been suggested as reasons for this phenomenon. Importantly, B-type natriuretic peptides are not specific for heart failure, but reflect haemodynamic myocardial stress independent of the underlying pathology, and thus are more 'markers' of the general cardiac state. Cut-points differ widely when comparing studies in patients with acute versus chronic dyspnoea. In patients with acute dyspnoea age-dependent cut-points should be used, while in patients with chronic dyspnoea (that is, slowly progressive breathlessness) at least thresholds below which heart failure can be excluded seem rather independent of age. Especially in the primary care setting where elderly patients with slowly progressive dyspnoea are investigated, the excellent exclusionary capacities of B-type natriuretic peptides are of great help to select those that require echocardiography to establish or eventually reject a diagnosis of heart failure.