PURPOSE: Heparin exposure is common prior to and essential during cardiac surgery which leads to a risk for heparin induced thrombocytopenia (HIT). We sought to identify risk factors associated with HIT in this patient population.
METHODS: We retrospectively reviewed all cardiac surgery patients between January 2003 and July 2009. HIT was diagnosed in patients with clinical suspicion and a positive ELISA HIT antibody test (OD > 0.4). Determining the incidence of HIT among types of cardiac surgery was the primary endpoint. Risk factors independently associated with HIT, identified by logistic regression analysis, was the secondary endpoint.
RESULTS: The cohort consisted of 11,340 subjects; 2% developed HIT; 0.6% had thrombosis associated with HIT. The incidence of HIT differed depending on the type of procedure performed: 1.05% for coronary artery bypass graft (CABG) surgery, 6.05% for combined CABG and valve surgery, 3.74% for valvular surgery, and 5.74% for aortic aneurysm/dissection, p<0.01. Logistic regression demonstrated that increasing age (odds ratio [OR]=1.03; 95% confidence interval [CI]: 1.02-1.04), female gender (OR=1.72, 95% CI: 1.29-2.31), African American race (OR=1.38; 95% CI: 1.03-1.86), preoperative heart failure (OR=1.39; 95% CI: 1.01-1.91), preoperative atrial fibrillation [Afib] (OR=2.32; 95% CI: 1.76-3.06), and preoperative stroke (OR=2.97; 95% CI: 1.84-4.80) were independently associated with the risk for HIT. Further, the risk factors associated with thrombosis included the use of preoperative unfractionated heparin (OR=2.27; 95% CI: 1.07-4.82), older age (OR=1.05; 95% CI: 1.03-1.08), BMI (OR=1.04; 95% CI: 1.01-1.08), and the presence of preoperative Afib (OR=2.24; 95% CI: 1.35-3.69).
CONCLUSION: The incidence of HIT is 2% in cardiac surgery patients. Patients undergoing valvular surgery or surgery of the aorta have a higher incidence of HIT compared to CABG. Risk factors associated with HIT include gender, age, prior history of Afib, heart failure, and prior stroke. The development of thrombosis in the face of HIT was influenced by the use of preoperative heparin and BMI.
CLINICAL IMPLICATIONS: The clinical suspicion for HIT must be higher for patients who have valve surgery or surgery of the aorta.
DISCLOSURE: Xiumei Sun, No Financial Disclosure Information; No Product/Research Disclosure Information