Association of hemoglobin levels with clinical outcomes in acute coronary syndromes in Koreans

Anemia is a well-known risk factor for cardiovascular disease. However, there are limited data on whether anemia on admission is a long-term prognostic factor in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention. We sought to evaluate the prevalence and prognostic consequences of anemia in patients with ACS treated with percutaneous coronary intervention in Korea. We retrospectively enrolled 1930 consecutive patients. Among the anemic population (hemoglobin [Hb] < 13 g/dL in men, and < 12 g/dL in women), we classified patients with Hb ≥ 7 g/dL, <10 d/dL as moderate anemia, other cases classified as mild anemia. Among patients with normal hemoglobin levels, we classified those with Hb > 16.5 g/dL in men, and > 16.0 g/dL in women, as having high hemoglobin. We examined the relationship between anemia with all-cause mortality and secondary outcomes – including cardiovascular mortality, myocardial infarction, stroke, and repeat revascularization. We classified 3.3%, 21.5%, and 5.3% of patients as moderate anemia, mild anemia, and high hemoglobin, respectively. During a median follow-up of 67.2 (interquartile range; 46.8–88.5) months, 74 (3.8%) patients died. Compared with patients with normal hemoglobin, we detected a significantly increased risk for all-cause mortality in patients with anemia (adjusted hazard ratios for moderate and mild anemia, respectively: 8.26 [95% confidence interval: 3.98–17.15], P < .001 and 2.60 [1.54–4.40], P < .001). Among patients with ACS, anemia is prevalent and is strongly associated with increased mortality and cardiovascular events. Clinical trials will prospectively evaluate the efficacy of treatment for anemia on the outcomes of patients with ACS.