Association of anemia with clinical outcomes in stable coronary artery disease.

Background: Although anemia is pathophysiologically associated with myocardial ischemia, there are scarce data on its clinical impact in patients with stable coronary artery disease on contemporary treatment. This study aims to describe the prevalence of anemia, and its association with symptoms and outcomes in this population.
Methods: We conducted a prospective cohort study in stable documented coronary artery disease patients. Anemia criteria was hemoglobin (Hb) <12 g/dl in women and <13 g/dl in men. Hemoglobin levels were divided in quartiles (Q) adjusted for sex. Major events included acute coronary syndromes, stroke and cardiovascular deaths. Secondary outcomes were presence of angina and chronic use of nitrates. Cox regression models were used to evaluate the independent effect of anemia on clinical outcomes.
Results: Among 310 patients, 71 (23%) met criteria for anemia. After a mean follow-up of 44+/-23 months, hemoglobin levels had a marked association with occurrence of major events (27% in Q1, 7% in Q2, 8% in Q3 and 12% in Q4; P<0.01). In multivariate analysis, anemia was independently associated with an increased risk of death [hazard ratio (HR) 6.5, 95% confidence interval (1.7-24.2)], major events [HR 3.3 (1.7-6.5)] and revascularization procedures [HR 2.3 (1.3-4.1)]. Persistent of angina symptoms (32 vs. 18%, P=0.01) and chronic use of nitrates (35 vs. 21%, P=0.02) were also more frequent among patients with anemia at baseline.
Conclusions: In patients with stable ischemic heart disease, presence of anemia, even mild, is associated with a worse prognosis. Strategies aiming at identifying reversible causes of anemia or new treatments should be evaluated in prospective clinical trials.