The Prevalence and Natural History of Anaemia
The prevalence of anaemia in heart failure (HF) is becoming better recognised, yet little is known about its natural history in a HF population. We examined the records of 200 consecutive patients who were admitted to our service with New York Heart Association (NYHA) class IV HF, survived and were followed for six months following discharge. Complete records were available on 120 patients. Anaemia was defined as a haemoglobin concentration of < 13 g/dL in males and < 12 g/dL in females. Forty-one patients (34%) were found to have anaemia of unknown cause on admission. At follow-up (mean time 6.1+0.3 months), 28 patients were persistently anaemic. The haemoglobin concentration in the remaining 13 had returned to normal. A further group of 11 patients had become anaemic during the six-month follow-up period. All patients had been treated with maximally tolerated medical therapy. Anaemia was found to be equally prevalent in patients with preserved systolic function HF. Factors found to be independently associated with lower haemoglobin at follow-up were female sex, a history of gastrointestinal disease, inflammatory disease and a low glomerular filtration rate (GFR). Haemoglobin concentration at follow-up was found, on univariate analysis, to be associated with an increased risk of a HF-related admission during the follow-up period and increased severity of HF symptoms. On multivariate analysis, haemoglobin concentration at follow-up was found to be an independent predictor of NYHA class III-IV symptoms. In conclusion, anaemia is prevalent in a population admitted with class IV failure. While the haemoglobin concentration had normalised in a significant number of patients during follow-up, the presence of anaemia six months after discharge was associated with having a HF-related readmission and independently associated with moderate-to-severe HF symptoms.
A number of recent reports have focused on the subject of anaemia in chronic heart failure (HF). Several studies from the 1990s showed that the mean haemoglobin in patients with congestive HF is about 12 g/dL. The initial paper to focus on anaemia specifically in HF patients demonstrated a prevalence of anaemia (defined as Hb < 12 g/dL) of 55.6% in a population attending a HF clinic, though this was in a select group of patients attending a nephro-cardiology clinic. Several subsequent studies have reported the prevalence of anaemia (with varying cut-off values for haemoglobin level) in HF patients as between 14% and 50%. Factors which were associated with the presence of anaemia in these studies included symptomatic severity of HF, impairment of renal function and other co-morbid conditions. Furthermore, anaemia has been identified as an independent predictor of mortality, and a predictor of hospital readmission in HF patients.
The cause of anaemia in most cases is not easily identified. Cardiac failure is associated with renal impairment, which may be an important factor in the development of anaemia. A low cardiac output may also impair bone marrow function. Right-sided HF can cause malabsorption, nutritional deficits and impaired metabolism. The elderly make up the majority of patients with HF, and the existence of co-morbidities in this population may be of relevance in the development of anaemia.
The effect of correction of anaemia on the heart has been most widely studied in patients with chronic renal disease. In the setting of haemodialysis patients, the treatment of anaemia with erythropoietin has been shown to increase exercise capacity and to reduce exercise-induced cardiac ischaemia. Structural benefits have also been observed, including a reduction of left ventricular hypertrophy, left ventricular end-diastolic and end-systolic diameters and an increase in left ventricular ejection fraction (LVEF). A more recent study showed that the beneficial cardiovascular effects seen with correction of anaemia in dialysis patients do not persist on discontinuation of erythropoietin therapy.
An initial non-randomised study using erythropoietin and intravenous iron to correct anaemia in HF patients whose treatment already conformed with best practice guidelines, demonstrated a significant improvement in New York Heart Association (NYHA) class, an increase in LVEF and a significant reduction in hospitalisations. A follow-up open-label randomised study by the same group provided similar results. Furthermore, correction of anaemia with erythropoietin and iron in HF patients has also been shown to be associated with significant improvements in peak VO2 and exercise duration.
Many questions remain unanswered in this evolving area. The prevalence of anaemia in an unselected community HF population, including those with preserved systolic function, requires further definition. To date, studies have looked at anaemia in HF patients based on haemoglobin concentrations assessed at one time point only. The natural history of anaemia in patients with HF over time and in response to maximally tolerated angiotensin-converting enzyme (ACE) inhibitor and beta blocker therapy is also unknown. The aim of our study was to investigate these issues in the population attending our HF service.
The prevalence of anaemia in heart failure (HF) is becoming better recognised, yet little is known about its natural history in a HF population. We examined the records of 200 consecutive patients who were admitted to our service with New York Heart Association (NYHA) class IV HF, survived and were followed for six months following discharge. Complete records were available on 120 patients. Anaemia was defined as a haemoglobin concentration of < 13 g/dL in males and < 12 g/dL in females. Forty-one patients (34%) were found to have anaemia of unknown cause on admission. At follow-up (mean time 6.1+0.3 months), 28 patients were persistently anaemic. The haemoglobin concentration in the remaining 13 had returned to normal. A further group of 11 patients had become anaemic during the six-month follow-up period. All patients had been treated with maximally tolerated medical therapy. Anaemia was found to be equally prevalent in patients with preserved systolic function HF. Factors found to be independently associated with lower haemoglobin at follow-up were female sex, a history of gastrointestinal disease, inflammatory disease and a low glomerular filtration rate (GFR). Haemoglobin concentration at follow-up was found, on univariate analysis, to be associated with an increased risk of a HF-related admission during the follow-up period and increased severity of HF symptoms. On multivariate analysis, haemoglobin concentration at follow-up was found to be an independent predictor of NYHA class III-IV symptoms. In conclusion, anaemia is prevalent in a population admitted with class IV failure. While the haemoglobin concentration had normalised in a significant number of patients during follow-up, the presence of anaemia six months after discharge was associated with having a HF-related readmission and independently associated with moderate-to-severe HF symptoms.
A number of recent reports have focused on the subject of anaemia in chronic heart failure (HF). Several studies from the 1990s showed that the mean haemoglobin in patients with congestive HF is about 12 g/dL. The initial paper to focus on anaemia specifically in HF patients demonstrated a prevalence of anaemia (defined as Hb < 12 g/dL) of 55.6% in a population attending a HF clinic, though this was in a select group of patients attending a nephro-cardiology clinic. Several subsequent studies have reported the prevalence of anaemia (with varying cut-off values for haemoglobin level) in HF patients as between 14% and 50%. Factors which were associated with the presence of anaemia in these studies included symptomatic severity of HF, impairment of renal function and other co-morbid conditions. Furthermore, anaemia has been identified as an independent predictor of mortality, and a predictor of hospital readmission in HF patients.
The cause of anaemia in most cases is not easily identified. Cardiac failure is associated with renal impairment, which may be an important factor in the development of anaemia. A low cardiac output may also impair bone marrow function. Right-sided HF can cause malabsorption, nutritional deficits and impaired metabolism. The elderly make up the majority of patients with HF, and the existence of co-morbidities in this population may be of relevance in the development of anaemia.
The effect of correction of anaemia on the heart has been most widely studied in patients with chronic renal disease. In the setting of haemodialysis patients, the treatment of anaemia with erythropoietin has been shown to increase exercise capacity and to reduce exercise-induced cardiac ischaemia. Structural benefits have also been observed, including a reduction of left ventricular hypertrophy, left ventricular end-diastolic and end-systolic diameters and an increase in left ventricular ejection fraction (LVEF). A more recent study showed that the beneficial cardiovascular effects seen with correction of anaemia in dialysis patients do not persist on discontinuation of erythropoietin therapy.
An initial non-randomised study using erythropoietin and intravenous iron to correct anaemia in HF patients whose treatment already conformed with best practice guidelines, demonstrated a significant improvement in New York Heart Association (NYHA) class, an increase in LVEF and a significant reduction in hospitalisations. A follow-up open-label randomised study by the same group provided similar results. Furthermore, correction of anaemia with erythropoietin and iron in HF patients has also been shown to be associated with significant improvements in peak VO2 and exercise duration.
Many questions remain unanswered in this evolving area. The prevalence of anaemia in an unselected community HF population, including those with preserved systolic function, requires further definition. To date, studies have looked at anaemia in HF patients based on haemoglobin concentrations assessed at one time point only. The natural history of anaemia in patients with HF over time and in response to maximally tolerated angiotensin-converting enzyme (ACE) inhibitor and beta blocker therapy is also unknown. The aim of our study was to investigate these issues in the population attending our HF service.
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