Pathophysiology of cardiorenal syndrome type 2 in stable chronic heart failure: workgroup statements from the eleventh consensus conference of the Acute Dialysis Quality Initiative (ADQI).

In cardiorenal syndrome (CRS) type 2, chronic heart failure (HF) results in the onset or progression of chronic kidney disease (CKD). Examples of CRS type 2 (CRS2) include progressive CKD resulting from chronic HF in congenital or acquired heart disease or from repeated bouts of acute decompensated HF. Animal data and clinical studies indicate that extended periods of chronic HF result in altered renal hemodynamics followed by progressive renal pathology. Experimental and clinical data indicate that CRS2 is characterized by mild to moderate proteinuria, a progressive decline of glomerular filtration rate, and an elevated expression of renal injury biomarkers. Important pathophysiological triggers of renal disease progression include chronic increases in renal venous pressure, maladaptive activation of the renin-angiotensin-aldosterone axis and the sympathetic nervous system, as well as a chronic inflammatory state. Intrarenal oxidative stress and proinflammatory signaling precipitate structural injury, including glomerulosclerosis and tubulointerstitial fibrosis. Yet, clinical interventional trials that directly test the impact of renin-angiotensin system antagonists and β-blockers on the progression of CKD in CRS2 are lacking. Secondary analyses of trials designed to assess the impact of these agents on cardiovascular endpoints have failed to show a consistent benefit regarding renal functional parameters. In contrast, left ventricular assist device placement and cardiac resynchronization therapy in HF patients consistently improved renal function, suggesting a marked potential for reversibility in many cases of CRS2. Future research should be directed towards the evaluation of novel biomarkers to improve the diagnosis, severity grading as well as our understanding of the pathophysiology of CRS2. In addition, there is a need for interventional trials in HF patients to address long-term renal endpoints incorporating clinical information and measures of renal function as well as renal injury.