Letter by Antonelli Incalzi et al Regarding Article, “Endogenous Erythropoietin and Outcome in Heart Failure”
To the Editor:
We read with interest the article by Belonje and colleagues.1 It has merit in exploring the prognostic implications of serum erythropoietin and ratio of observed to expected erythropoietin in a large, unselected heart failure population (mean age, 71 years; women, 38%). A considerable proportion of these patients are likely affected by chronic obstructive pulmonary disease because its prevalence has been estimated to be 4% to 10% in the general population (with the number increasing with age and varying according to risk factors)2 and up to 33% in heart failure patients ≥65 years of age.3 As a consequence, some proportion of these patients are likely to have chronic obstructive pulmonary disease–related arterial hypoxemia, which is the strongest promoter of erythropoietin secretion.4 Accordingly, the observed erythropoietin levels cannot not be ascribed exclusively to heart failure and related pathogenetic mechanisms such as depressed renal function or inflammatory inhibition of bone marrow proliferation. Neither arterial blood gases nor percutaneous oxygen saturation is provided by the authors. In our opinion, the lack of this information makes it impossible to correctly interpret the prognostic meaning of erythropoietin concentration in heart failure. Thus, in both the clinical scenario and epidemiological research, it seems sensible to screen patients with heart failure for comorbid chronic obstructive pulmonary disease and arterial hypoxemia; unrecognized and then uncorrected hypoxemia is more likely to have prognostic implications than the ensuing increased erythropoietin.