[ACE inhibition in heart failure and compromised kidney function]

If ACE-inhibitors are considered for therapy in patients with heart failure, the actual renal function has to be taken into account. In patients with reduced intravascular volume, e.g. during therapy with diuretics, the renin-angiotensin system is activated. In this situation, the renin-angiotensin-system contributes to the maintenance of arterial blood pressure and glomerular filtration rate by angiotensin II mediated vasoconstriction in vas efferens and systemic circulation. A sudden complete inhibition of the renin-angiotensin system therefore may cause a pronounced decrease in blood pressure and a reduction in glomerular filtration rate (impaired renal excretory function). In patients with heart failure concomitant chronic renal failure, the use of ACE-inhibitors is without major risk; however, the clinical efficacy may be limited. This does not apply to patients with diabetes, where the risk for impairment of renal function is increased. The potential advantage of short acting ACE-inhibitors such as captopril may clinically be relevant only in patients with very advanced severe heart failure and low arterial pressure. In any case, it is recommended to start ACE-inhibitors with a low dose and withdraw diuretics one or two days before in order to restore the intravascular volume.