Phase 3 Study on the Efficacy and Safety of Human Plasma Derived Antithrombin (Atenativ) in Heparin-Resistant Patients Scheduled to Undergo Cardiac Surgery Necessitating Cardiopulmonary Bypass

Inclusion Criteria:

1. Planned cardiac surgery with CPB

2. Heparin-resistant patients (pre-CPB Hemochron ACT less than 480 s in the measurementtaken between 2-5 minutes following intravenous administration of 500 U/kg UFH)

3. Patients between 18 and 85 years of age, inclusive

4. Freely given written or electronic informed consent

5. In female patients of childbearing potential, a pre-existing negative pregnancy testwithin 14 days prior to surgery

Exclusion Criteria:

1. Receiving, or have received within the timeframes specified, one or more of thefollowing medications prior to the start of surgery:

2. vitamin K antagonists (within 3 days)

3. direct oral anticoagulants (within 2 days)

4. thienopyridines (ticlopidine within 14 days, prasugrel within 7 days, orclopidogrel within 5 days), unless platelet function is satisfactory accordingto local standard of care assessment

5. ticagrelor (within 5 days), unless platelet function is satisfactory accordingto local standard of care assessment

6. glycoprotein IIb/IIIa antagonist (within 24 hours)

7. Pre-existing coagulopathy, a history of bleeding problems, a history of bleedingproblems, or a laboratory-diagnosed bleeding disorder (e.g., von Willebrand disease,platelet disorder)

8. Renal insufficiency, defined as serum creatinine level >2.0 mg/dL

9. Thrombocytosis, defined as platelet count >400,000 per μL

10. Known hypersensitivity or allergic reaction to antithrombin or any of the excipientsin Atenativ i.e., human albumin, sodium chloride, acetyl tryptophan, caprylic acid

11. History of anaphylactic reaction(s) to blood or blood components

12. Refusal to receive transfusion of blood or blood-derived products

13. Current participation in another interventional clinical trial or previousparticipation in the current trial

14. Treatment with any IMP within 30 days prior to screening visit