A group evaluating data from the Beta-Blocker Evaluation
of Survival Trial took a different approach [46].
They assumed that hyperuricaemia without CKD is primarily
due to increased production of uric acid from the
failing heart, while hyperuricaemia in patients with CKD
is in large part due to impaired renal excretion of urate.
The conclusion was that hyperuricaemia is associated
with a poor outcome in CHF without CKD, but not in
those with CHF and CKD. This suggests that hyperuricaemia
in CHF without CKD might be ascribed to increased
XO activity. Although the role of XO in CHF is
not clearly established, it appears that its inhibition (independent
of urate-lowering) in patients with hyperuricaemia
may have a beneficial effect on endothelial cell function,
myocardial function and ejection fraction, while in contrast,
reducing urate levels with probenecid or benzbromarone
does not improve endothelial cell function or
haemodynamic impairment, despite a significant decrease
in serum urate level [for references see 47-50]. These data
suggest that increased XO activity, rather than the serum
urate level per se, is involved in CHF pathophysiology.