Effects of anaemia on cardiovascular status

Cardiomyopathy is a common, heterogeneous and important cause of cardiac mo rbidity and mortality in uraemic patients. The risks of ischaemic heart dis ease, cardiac failure, and death increase progressively from lowest risk in patients with concentric left-ventricular hypertrophy, to medium risk in p atients with left-ventricular dilatation but intact systolic function, to h ighest risk in patients with systolic dysfunction. Anaemia and hypertension are the reversible risk factors most consistently linked with the developm ent of cardiomyopathy in these patients. Longitudinal data show that anaemi a predisposes individuals to initial left ventricular dilatation, with comp ensatory hypertrophy, which may progress to systolic dysfunction. This proc ess typically begins at glomerular filtration rates between 25 and 50 ml/mi n, and haemoglobin concentrations that are even slightly below normal are a ssociated with progressive cardiac enlargement. Several observational studies have suggested that the correction of anaemia may reduce mortality and hospitalization rates in dialysis patients. The a vailable evidence supports maintaining haemoglobin concentrations to greate r than 11 g/dl. Whether a haemoglobin threshold exists above which no furth er benefit is seen remains controversial, partially because recent randomiz ed controlled trials have intervened relatively late in the anaemia-cardiom yopathy-cardiac failure-death continuum. One large randomized controlled tr ial showed no benefit from normalizing the haemoglobin concentration in hae modialysis patients with well-established cardiac disease; however, these p atients had been exposed to anaemia for long periods of time and were at th e extreme end of the cardiorenal disease spectrum. Other researchers have d emonstrated a protective effect of normalizing the haemoglobin concentratio n in patients with asymptomatic, and hence presumably early, cardiomyopathy . The psychological benefits and improvements in exercise tolerance and quali ty of life resulting from normalization of the haemoglobin concentration ar e becoming clearer. However, conclusive evidence of the cardiovascular bene fits of earlier, more aggressive treatment of renal anaemia as well as of t he exact target haemoglobin concentration at which risk begins to develop i s still lacking. The results of ongoing trials should help to clarify both of these issues within the next 5 years.