Cardiorenal syndrome: Epidemiology, pathogenesis, and outcomes

The cardiorenal syndrome is a broad term used to describe the association of heart failure and renal impairment. A recent classification has sought to separate different clinical presentations, but the underlying pathophysiological causes are not readily differentiated in this way. Patients developing the cardiorenal syndrome are at major risk of mortality and morbidity due to multiple and complex interactions. There is now growing interest in the role of anemia in worsening outcome. Standard medical therapy, such as β-blockers and renin-angiotensin blocking agents, are effective, but underused in patients with heart failure and renal impairment, and other standard therapies such as high-dose diuretics potentially have nephrotoxic effects; the response to diuretic therapy is also blunted in the presence of renal dysfunction. Emerging therapies such as peritoneal dialysis and hemofiltration have potential to improve the outcome of hemodynamically unstable patients with severe cardiorenal disease. As is the case in all areas of medicine, preventative strategies are of paramount importance, and therapies that help prevent development of cardiovascular complications in patients with chronic kidney disease and, conversely, strategies that allow successful treatment of acute or chronic heart failure without exacerbation of renal dysfunction, are awaited.