Hematocrit value on intensive care unit entry influences the frequency of Q-wave myocardial infarction after coronary artery bypass grafting. The Institutions of the Multicenter Study of Perioperative Ischemia (McSPI) Research Group.
OBJECTIVE
No data exist regarding "the best" hematocrit value after coronary artery bypass graft surgery. Transfusion practice varies, because neither an optimal hematocrit value nor a uniform transfusion trigger criterion has been determined.


METHODS
To investigate the optimal hematocrit value, we studied 2202 patients undergoing coronary bypass. The hematocrit value on entry into the intensive care unit (IHCT) was categorized into three groups: high (> or = 34%), medium (25% to 33%), and low (< or = 24%). Characteristics and adverse events (outcomes) were compared, and the effect of IHCT on the risk of myocardial infarction was determined by logistic regression.


RESULTS
High IHCT (> or = 34%) was associated with an increased rate of myocardial infarction (8.3% vs 5.5% vs 3.6%; p < or = 0.03, high, medium vs low) and with more severe left ventricular dysfunction (11.7% vs 7.4% and 5.7%; p=0.006, high, medium vs low). Mortality rate increased with higher IHCT when all the high-risk subgroups were combined (8.6% vs 4.5% vs 3.2%; p < 0.001, high, medium vs low). By multivariate analysis, IHCT remained the most significant predictor of adverse outcomes (relative risk high vs low 2.22, 95% confidence interval: 1.04 to 4.76). No characteristic, event, medication, or transfusion therapy confounded the relationship between IHCT and outcome.


CONCLUSIONS
High IHCT is associated with a higher rate of myocardial infarction and is an independent predictor of infarction. On the basis of the risk of myocardial infarction, there is no rationale for transfusion to an arbitrary level after coronary artery bypass grafting.
Spiess
B D
BD
Department of Anesthesiology, University of Washington, Seattle 98195, USA.
Ley
C
C
Body
S C
SC
Siegel
L C
LC
Stover
E P
EP
Maddi
R
R
D'Ambra
M
M
Jain
U
U
Liu
F
F
Herskowitz
A
A
Mangano
D T
DT
Levin
J
J
D000740:Anemia / Q000097:blood / Q000453:epidemiology; D001803:Blood Transfusion / Q000706:statistics & numerical data*; D001026:Coronary Artery Bypass; D004562:Electrocardiography; D005260:Female; D006400:Hematocrit; D006801:Humans; D007362:Intensive Care Units; D007431:Intraoperative Complications / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000097:blood / Q000453:epidemiology*; D011183:Postoperative Complications / Q000097:blood / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors