Diagnostic and therapeutic potential of the endothelin system in patients with chronic heart failure

There is now considerable evidence to support a role for the endothelin (ET) system in the pathogenesis and progression of chronic heart failure (CHF). As such, the potential exists for this system to be useful in both diagnosis (by measurement of peptide levels in plasma and other body fluids) and treatment (by pharmacological blockade) of this condition. Plasma levels of endothelin-1 (ET-1) are elevated in CHF and the magnitude of elevation correlates with disease severity. ET-1 levels in plasma predict subsequent mortality in patients with CHF. ET-1 may also contribute to symptoms associated with CHF, such as exercise intolerance. In the diagnosis of CHF, plasma levels of ET-1 appear to be a less powerful discriminator between patients with mild disease and control subjects with normal ventricular function on multivariate analyses, compared to brain natriuretic peptide (BNP), or its N-terminal fragment. ET-1 concentrations are also elevated in the saliva of patients with CHF and may represent an alternative approach to assessment of the status of the ET system in these patients. Specific ET receptor antagonists (both mixed and ET(A)-selective) have been developed. Studies with these agents in animal models of CHF have demonstrated beneficial effects via both haemodynamic and non-haemodynamic pathways. A number of short-term clinical studies have been performed demonstrating improvements in haemodynamic parameters without neurohormonal activation. Long-term clinical studies with ET receptor antagonists are currently underway to definitively test the impact of blockade of this system on mortality and major cardiovascular endpoints. Endothelin converting enzyme (ECE) inhibitors represent an alternative strategy of ET blockade, and early data from animal models suggest these agents may be of clinical utility, either alone or, more likely, in combination with other zinc metallopeptidases.