Leukoreduced Packed Red Cells: Do They Have a Role in Decreasing the Incidence of Heparin Induced Thrombocytopenia?.

It has been demonstrated that neutrophils activate macrophages via the heparin binding protein, thus possibly contributing to the incidence of heparin induced thrombocytopenia (HIT).

It would follow that the incidence of thrombocytopenia and its sequelae may be reduced by using leukoreduced blood in patients undergoing cardiac bypass surgery. We had a unique opportunity to study this hypothesis at our institution. Due to a policy change all patients undergoing cardiac bypass surgery received LR blood intra-operatively prior to April 2005.

Subsequent to this period non-LR blood was utilized in all patients. A retrospective chart review of 197 non-LR and 316 LR patients was done. The platelet count on admission, the first five days post- op, the day of discharge, the percent drop in platelet count post-op and heparin antibody (HA) test were obtained. Thrombocytopenia was defined as an overall drop in platelet count by > 50%. The CABG and the non-CABG patients were looked at separately.

The results are as follows:

In both the LR and non-LR populations there is only a 0.6% difference in the number of patients with a > 50% platelet drop. The relative risk is 1.01 with the 95% confidence interval of (0.88, 1.15). This is a relatively narrow confidence interval reflective of the relatively large sample size.

Heparin antibody testing was not done on all the patients. Only those with persistent or profound thrombocytopenia had the test ordered. Overall heparin antibody positivity in both cohorts was not statistically different.

The LR arm had a slightly higher positivity rate overall. The risk ratio is 1.25 indicating that the non-LR arm is 25% more likely to have a positive antibody test compared to the LR arm. The higher positivity rate in non-CABG patients may be due to the more complex nature of the surgery relative to CABG surgery.

The non-CABG group has a higher percent of heparin antibody positivity in the LR arm.

This inconsistency may be secondary to the smaller sample size of this group. In both the CABG or non-CABG groups, there was no statistically significant difference in the percent platelet drop or heparin antibody positivity.

One can conclude that leukoreduction of red blood cell products during cardiac surgery does not significantly impact on thrombocytopenia or the development of HIT.