Ultrafiltration in acute decompensated heart failure: friend or foe for the kidney?

Background: Congestion represents the common pathogenetic mechanism of both the acute decompensation episodes of heart failure and progression of the syndrome; it also increases the risk of rehospitalization, and is associated with renal function worsening. Diuretic therapy still represent the mainstay of therapy of congestion; however, ultrafiltration (i.e. fluid removal from blood by hemoconcentration obtained with dedicated machines) has been recently suggested as a more rapid and effective alternative to the conventional therapeutic approach. Methods: On the basis of the proposed mechanisms of action and rationale of ultrafiltration in heart failure, this review is aimed at discussing efficacy and safety issues of this mechanical modality of fluid removal, with special regard to renal function. Results: The available evidence, also including recent data from a randomized clinical trial comparing ultrafiltration with adequately managed diuretic therapy (the CARRESS study), does not support its extensive employment as an alternative to well protocolized conventional diuretic therapy, especially in patients with acute decompensated heart failure. As a matter of fact, in this latter case highly negative effects on renal function are also to be expected. Conclusion: Ultrafiltration should be reserved to very selected patients with advanced heart failure and true diuretic resistance, as part of a more complex strategy aiming at an adequate control of fluid retention.