Anemia as an Independent Predictor of Perioperative and Long-Term Cardiovascular Outcome in Patients Scheduled for Elective Vascular Surgery

Abstract

Anemia is common in patients scheduled for vascular surgery and is a risk factor for adverse cardiac outcome. However, it is unclear whether this is an independent risk factor or an expression of underlying co-morbidities. In total, 1,211 patients (77% men, 68 +/- 11 years of age) were enrolled. Anemia was defined as serum hemoglobin levels <13 g/dl for men and <12 g/dl for women and was divided into tertiles to compare mild (men 12.2 to 13.0, women 11.2 to 12.0), moderate (men 11.0 to 12.1, women 10.2 to 11.1), and severe (men 7.2 to 11.0, women 7.5 to 10.1) anemia with nonanemia. Outcome measurements were 30-day and 5-year major adverse cardiac events (MACEs; cardiac death or myocardial infarction). All risk factors were noted. Multivariable logistic and Cox regression analyses were used, adjusting for all cardiac risk factors, including heart failure and renal disease. Data are presented as hazard ratios with 95% confidence intervals. In total, 74 patients (6%) had 30-day MACEs and 199 (17%) had 5-year MACEs. Anemia was present in 399 patients (33%), 133 of whom had mild anemia, 133 had moderate anemia, and 133 had severe anemia. Presence of anemia was associated with renal dysfunction, diabetes, and heart failure. After adjustment for all clinical risk factors, 30-day hazard ratios for a MACE per anemia group were 1.8 for mild (0.8 to 4.1), 2.3 for moderate (1.1 to 5.4), and 4.7 for severe (2.6 to 10.9) anemia, and 5-year hazard ratios for MACE per anemia group were 2.4 for mild (1.5 to 4.2), 3.6 for moderate (2.4 to 5.6), and 6.1 for severe (4.1 to 9.1) anemia. In conclusion, the presence and severity of preoperative anemia in vascular patients are significant predictors of 30-day and 5-year cardiac events, regardless of underlying heart failure or renal disease.