Association between admission anemia and long-term mortality in patients with acute myocardial infarction: results from the MONICA/KORA myocardial infarction registry.

BACKGROUND: Previous studies have shown that the presence of anemia is associated with increased short- and long-term outcomes in patients with acute myocardial infarction (AMI). This study aims at examining the impact of admission anemia on long-term, all-cause mortality following AMI in patients recruited from a population-based registry. Contrary to most prior studies, we distinguished between patients with mild and moderate to severe anemia. METHODS: This prospective study was conducted in 2011 patients consecutively hospitalized for AMI that occurred between January 2005 and December 2008. Patients who survived more than 28 days after AMI were followed up until December 2011. Hemoglobin (Hb) concentration was measured at hospital admission and classified according to the World Health Organization (WHO). Mild anemia was defined as Hb concentration of 11 to < 12 g/dL in women and 11 to < 13 g/dL in men; moderate to severe anemia as Hb concentration of < 11 g/dL. Adjusted Cox regression models were calculated to compare survival in patients with and without anemia. RESULTS: Mild anemia and moderate to severe anemia was found in 183 (9.1%) and 100 (5%) patients, respectively. All-cause mortality after a median follow-up time of 4.2 years was 11.9%. The Cox regression analysis showed significantly increased mortality risks in both patients with mild (HR 1.74, 95% CI 1.23-2.45) and moderate to severe anemia (HR 2.05, 95% CI 1.37-3.05) compared to patients without anemia. CONCLUSION: This study shows that anemia adversely affects long-term survival following AMI. However, further studies are needed to confirm that anemia can solely explain worse long-term outcomes after AMI.