HEMATOCRIT VALUE ON INTENSIVE-CARE UNIT ENTRY INFLUENCES THE FREQUENCY OF Q-WAVE MYOCARDIAL-INFARCTION AFTER CORONARY-ARTERY BYPASS-GRAFTING

Objectives: No data exist regarding ''the best'' hematocrit value afte r coronary artery bypass graft surgery. Transfusion practice varies, b ecause neither an optimal hematocrit value nor a uniform transfusion t rigger criterion has been determined. Methods: To investigate the opti mal hematocrit value, we studied 2202 patients undergoing coronary byp ass. The hematocrit value on entry into the intensive care unit (IHCT) was categorized into three groups: high (greater than or equal to 34% ), medium (25% to 33%), and low (less than or equal to 24%). Character istics and adverse events (outcomes) were compared, and the effect of IHCT on the risk of myocardial infarction was determined by logistic r egression. Results: High IHCT (greater than or equal to 34%) was assoc iated with an increased rate of myocardial infarction (8.3% vs 5.5% vs 3.6%; p less than or equal to 0.03, high, medium vs low) and with mor e severe left ventricular dysfunction (11.7% vs 7.4% and 5.7%; p = 0.0 06, high, medium vs low). Mortality rate increased with higher IHCT wh en 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 hig h vs low 2.22, 95% confidence interval: 1.04 to 4.76). No characterist ic, event, medication, or transfusion therapy confounded the relations hip between IHCT and outcome. Conclusion: High IHCT is associated with a higher rate of myocardial infarction and is an independent predicto r of infarction, On the basis of the risk of myocardial infarction, th ere is no rationale for transfusion to an arbitrary level after corona ry artery by-pass grafting.