Abstract 17396: Iron Deficiency as the Most Ominous Substrate for Anemia in Patients Undergoing Coronary Artery Bypass Surgery
Background: Whilst pre-operative anemia escalates morbidity and mortality after coronary artery bypass grafting (CABG), it is unclear whether its different etiologies confer different magnitudes of risk. Because iron is quantitatively the most important biocatalyst in human physiology, we hypothesized that iron deficiency (ID) anemia (IDA) might confer the greatest hazard. Additionally, we supposed that ID even in the absence of anemia might be detrimental.
Methods: We analysed hospital outcomes in 1910 CABG patients (mean [±SD] age 67±10 years, EuroSCORE 4±3%, 79% male, 36% CCS class>2). The combination of a red cell distribution width≥15% and a mean cell volume ≤80fL was utilised to identify ID as it has a ≥90% sensitivity and specificity for this diagnosis. A hemoglobin <13g/dL in males and <12g/dl in females defined anemia.
Results: On admission, 70%, 27%, and 3% of patients had no anemia, non-iron deficiency anemia (NIDA), and IDA, respectively. Patients with IDA were more likely to be female (38% vs 21%), diabetic (53% vs 25%), with poorer ejection fractions (51% vs 33% with EF<50%), more congestive symptoms (15% vs 5%), and higher CCS class (2.5±1.6 vs 2.1±1.2), EuroSCOREs (5±3 vs 4±3) and post-op renal (15% vs 8%) and neurological (16% vs 5%) complications (all P<0.05). Over a median (±IQR) hospital stay of 10±12 days, 46 (2.4%) patients died. IDA predicted inpatient mortality (HR 3.9, CI: 1.6-9.3, P=0.002) independently of all covariates including the EuroSCORE, and conferred a greater risk than NIDA (Fig A). Interestingly, ID per se also predicted an escalated risk of death (unadjusted HR 3.3, CI:1.4-7.8, P=0.007, Fig B) and did so independently of the presence of anemia (ID adjusted HR 2.6, CI:1.1-6.5, P=0.03).
Conclusions: Pre-operative iron deficiency is the most ominous cause of anemia in CABG patients and confers adversity even in the absence of anemia. Optimizing iron status in anemic and non-anemic subjects might improve outcomes.
- © 2011 by American Heart Association, Inc.