Renal replacement therapy for heart failure patients: in whom, when and which therapy to use?

It has long been recognized that chronic or acute heart failure can lead to initiation or progression of renal dys- function or insufficiency. More recently, it has been shown that the cross-talk is bi-directional and that primary re- nal dysfunction or insufficiency represents an independent cardiovascular risk factor. This bi-directional cross-talk be- tween the heart and kidneys was defined as 'the cardiorenal syndrome' (CRS). CRS is associated with different clinical conditions and heart-kidney disorders and varies according to the initiating factor of the syndrome. In a recent state-of- the-art paper, Roncoet al. (1) proposed a new classification of CRS that includes five subtypes based on the primary cardiac or renal dysfunction as well as the acute or chronic clinical evolution. Acute CRS was categorized into type 1, characterized by rapid worsening of cardiac function lead- ing to acute kidney injury or type 3, which is an acute reno- cardiac syndrome characterized by primary abrupt worsen- ing of kidney function leading to acute cardiac dysfunction. Chronic CRS was classified into type 2, characterized by chronic heart dysfunction and failure causing progressive deteriorationofkidneyfunction,andtype4,whichincludes a chronic renocardiac syndrome characterized by primary chronic kidney disease (CKD) followed by cardiac and vas- cular complications. A secondary type 5 CRS was defined as combined cardiac and renal dysfunction secondary to systemic diseases or to multi-organ failure. From the clinical and therapeutic point of view, practic- ing nephrologists most frequently observe the chronic CRS types in patients having renal disorders due to or associated with severe primary cardiac dysfunction.