Conservative Versus Liberal Red Cell Transfusion in Myocardial Infarction Trial: The CRIT Pilot

The current standard of care for patients with heart attacks is to transfuse red blood cells when the hematocrit (red blood cell count) drops below 30 percent. However, there is little scientific basis for this current standard, and recent research has demonstrated that it is safe to allow the hematocrit (red blood cell count) to drop significantly lower in severely ill medical patients and in patients with heart disease undergoing major surgery. The investigators therefore propose this pilot trial to begin to determine whether or not it is safe to apply a more conservative blood transfusion strategy to patients with heart attacks.

In this study, patients who are within 72 hours of the onset of a heart attack and who are anemic (have a low red blood cell count) will be randomly assigned to one of two transfusion strategies while they are in the hospital: a liberal strategy of transfusing blood when the hematocrit falls below 30 percent (the current standard) or a conservative strategy of transfusing blood only when the hematocrit falls below 24 percent. It will then be determined which group fares better over the next 30 days.

The plan is to enroll 92 patients in this pilot trial in order to allow the researchers to plan for a much larger, definitive trial of this important question. It is anticipated that the conservative transfusion strategy will be similar to the standard (liberal) strategy in terms of patient outcomes.

Inclusion criteria

All of the following must be present:

• Acute myocardial infarction with presentation within 72 hours of randomization (acute myocardial infarction is defined as ischemic-type chest discomfort lasting at least 30 minutes associated with creatinine kinase MB (CKMB) or troponin >upper limit of normal [ULN])
• Admission to CCU
• Hematocrit .30 or less
• Written, informed consent

Exclusion criteria

• Inability or unwillingness to receive red cell transfusions
• Active bleeding (overt blood loss accompanied by a decrease in hematocrit of at least 5% in the preceding 12 hours)
• Receipt of red cell transfusion within 7 days of randomization
• Prior severe transfusion reaction
• Pregnancy
• Imminent death
• Decision to provide limited care
• Age <21
• Participation in another clinical trial in which blood transfusion is a requirement or a component of a primary or secondary endpoint
• Previous participation in the CRIT Pilot