This study was undertaken to review the incidence of heparin-induced thrombocytopenia (HIT) in this particular patient population because of a perceived increase in incidence.
A retrospective review of medical charts and data from the Society of Thoracic Surgery database was undertaken. Our group performed 672 total cardiac surgery cases from January 1, 2007 through December 31, 2007 and all but one received unfractionated heparin intra-operatively (excluded case had a history of HIT). Two hundred ninety four (43.8%) were off-pump coronary artery bypass grafts (CABG), 44 (6.5%) were on-pump CABG, 200 (29.8%) were valve replacements/repairs and 134 (19.9%) were concomitant with other surgical procedures. HIT was defined as a decrease in platelets post-operatively of greater than or equal to 50% or an absolute platelet count of less than 150,000 and a positive enzyme-linked immunosorbent assay or heparin-induced platelet aggregation assay.
HIT was diagnosed in 2.5% (17/672) of the cardiac surgeries performed. No cases of HIT were found in the off-pump population. HIT occurred in 4% (8/200) of valve replacement/repairs and 5% (17/334) of valve surgeries combined with other procedures. Mortality rate among HIT cases was 17.6% (3/17). Two of the cases died of sepsis (one associated with a perforated cecum, one from peritonitis) while the third succumbed to limb ischemia and pneumonia. A venous (4 cases) or arterial (1 case) thrombosis occurred in 29.4% (5/17).
In our group no cases of HIT occurred in the off-pump CABG group rather all incidences occurred in the valve replacements/repairs utilizing cardiopulmonary bypass. The incidence of HIT, mortality and thrombosis rate were not dissimilar to that reported in the literature (incidence in the literature 2–3%, 8–25% and 29–50% respectively).
It is possible that off-pump CABG surgery may decrease the incidence of HIT. If this is borne out in future study consideration should be given to increased use of this technique.
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