Abstract

Anemia has recently been associated with increased mortality in patients who undergo percutaneous coronary intervention. The mechanisms associated with increased mortality among patients who have anemia have not been defined. We sought to determine whether patients who had anemia and acute myocardial infarction (AMI) might be at higher risk for bleeding or cardiogenic shock during acute hospitalization compared with patients who did not have anemia. This population-based study included 5,378 residents of the Worcester metropolitan area who were hospitalized with a diagnosis of AMI in five 1-year periods from 1995 to 2003. Patients were analyzed according to the presence or absence of anemia (hematocrit <39% in men and <36% in women) and quintiles of baseline hematocrit levels. Differences in the frequency of death, cardiogenic shock, and major bleeding during hospitalization were analyzed in relation to the presence of anemia. Anemia was present in 31.3% of patients who were hospitalized with AMI. Mortality and bleeding complications were related to the presence of anemia on admission for all types of AMI and across a broad spectrum of anemia severities. In a multivariable model that adjusted for baseline and treatment covariates, the odds ratios for adverse events for patients who had anemia (compared with those who did not) were 1.43 (95% confidence interval 1.12 to 1.84) for hospital mortality and 3.57 (95% confidence interval 2.75 to 4.64) for major bleeding. Development of cardiogenic shock was not related to the presence of anemia (odds ratio 0.89, 95% confidence interval 0.64 to 1.23). In conclusion, these findings suggest that bleeding complications are a potential mechanism for increased mortality among patients who have anemia and present with AMI.