The cardio-renal anaemia syndrome: does it exist?

Abstract

Many patients in our nephrology department who have anaemia and chronic kidney insufficiency (CKI) show evidence of congestive heart failure (CHF). This triad of anaemia, CKI and CHF is known as the cardio-renal anaemia syndrome. The three conditions form a vicious circle, in which each condition is capable of causing or being caused by another. Anaemia can increase the severity of CHF and is associated with a rise in mortality, hospitalization and malnutrition. Anaemia can also further worsen renal function and cause a more rapid progression to dialysis than is found in patients without anaemia. Uncontrolled CHF can cause rapid deterioration of renal function and anaemia. CKI can also cause anaemia, as well as worsen the severity of CHF, and is associated with increased mortality and hospitalization in patients with CHF. Aggressive therapy against CHF with all the conventional medications at the accepted doses often fails to improve the CHF if anaemia is also present but is not treated. In studies in which the anaemia was corrected with s.c. erythropoietin and, in some cases, with i.v. iron, however, the cardiac function improved, as assessed by measurement of the left ventricular ejection fraction and oxygen utilization during maximal exercise. Symptomatic patient functioning improved, as monitored by shortness of breath and fatigue on exertion, and the need for hospitalization and oral and i.v. diuretics markedly decreased. The quality of life, as judged by different criteria, also improved. The glomerular filtration rate, which fell rapidly when the anaemia was untreated, stabilized in patients when their anaemia was treated. Nephrologists need to assess the cardiac status of all patients with CKI carefully, and this includes an echocardiogram along with possibly measuring the levels of B-type natriuretic peptide. Nephrologists also need to use the indicated agents for CHF at the recommended doses, while cardiologists and internists need to be more aware of the importance and lethal effects of even mild anaemia and the benefits of its treatment in CHF and CKI. Cooperation between these specialists will allow better and much earlier treatment of the anaemia, CHF and CKI, and prevent the deterioration of all three conditions.