Anaemia in heart failure may impact prognosis

By Laura Cowen

Anaemia is common in patients with heart failure (HF), regardless of the underlying phenotype, and is often associated with iron deficiency, UK researchers report.

Furthermore, both anaemia and iron deficiency were associated with increased all-cause and cardiovascular mortality and may therefore "be therapeutic targets in this population", say John Cleland and colleagues, from the University of Hull.

More than a quarter (27.8%) of the 4456 patients (median age 73 years, 60.5% men) referred to a single outpatient clinic with suspected HF over a 10-year period had anaemia.

And this proportion increased to one-third among the patients with echocardiographic and biomarker criteria for HF - left ventricular ejection fraction less than 40%; left ventricular ejection fraction greater than 40% but with left ventricular dysfunction or hypertrophy plus plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) above 400 pg/mL; or just plasma NT-proBNP levels above 400 pg/mL - compared with 13.4% among those who lacked these features.

Among the patients with anaemia, between 43.2% and 68.0% had a low serum iron concentration or transferrin saturation, depending on the definition applied (conservative vs liberal), compared with 14.7% to 35.2% of the patients without anaemia.

In addition, the researchers note that 75.5% of the 2395 patients with complete haematinic data had either anaemia or iron deficiency when the more liberal criteria were applied.

At 5 years, estimated cumulative survival was around 55-65% in the patients with HF and 75-85% in those with uncertain or no HF. Multivariate analysis showed that lower haemoglobin and serum iron levels were significantly and independently associated with higher all-cause mortality, at hazard ratios of 0.92 and 0.98, respectively, and cardiovascular mortality at hazard ratios of 0.94 and 0.97, respectively.

Furthermore, "[e]limination of iron or haemoglobin from the multivariable model strengthened the association of the other with outcome", the researchers remark in JAMA Cardiology.

"Therefore, it is likely that both the severity of anemia and iron deficiency contribute to an adverse outcome in patients with HF", they add.

Cleland and co-authors also note that the prevalence of anaemia was poorly related to serum ferritin and ferritin was not associated with prognosis. It was, however, positively associated with high-sensitivity C-reactive protein "suggesting that high levels may reflect inflammation rather than iron repletion in the setting of HF", they say.

The authors conclude that their data "should help with the planning, execution, and interpretation of future interventional trials designed to treat iron deficiency and/or anemia".

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