Study Objectives: To assess the cross-reactivity of danaparoid sodium in patients undergoing cardiovascular surgery.

Design: Prospective investigation.

Setting: A major European heart center and university hospital.

Patients: 81 patients who underwent cardiovascular surgery during the period between January 1998 and April 1999 and were diagnosed with heparin-induced thrombocytopenia (HIT) II.

Interventions: Testing was performed in patients who revealed a decrease in the platelet count >30% or a platelet count <100,000/μL during heparin therapy. Testing for HIT was performed by the use of the heparin-induced platelet-aggregation assay. Patients were evaluated as positive if an agglutination occurred in two of four of the 0.2 IU/mL heparin chambers. Patients were judged to be cross-reactive with danaparoid sodium when an agglutination occurred in two of four chambers that contained 0.2 IU/mL Orgaran.

Measurements and Main Results: 281 patients (5.4% of the patients who underwent surgery during the period of the investigation) were tested for HIT II. Of these, 81 (1.5% of the total) gave a positive heparin-induced platelet-aggregation assay and 23 (28%) revealed a cross-reactivity with danaparoid sodium.

Conclusion: Cross-reactivity with heparin-induced platelet antibodies occurred in 28% of the patients who tested positive for heparin-platelet antibodies. In these patients, Orgaran™ would not have been a safe option. In patients with HIT II undergoing cardiac surgery, cross-reactivity with danaparoid sodium must be excluded before initiation of therapy with Orgaran, otherwise, or in cases of cross-reactivity, other options such as r-hirudin are preferred.