Safety and Efficacy of Preoperative Antithrombin Supplementation in Patients Undergoing High-Risk Cardiopulmonary Bypass

This is a prospective, multicenter, randomized, double-blind, placebo-controlled study. The purpose of this study is to determine the safety and effectiveness of human-derived antithrombin III (AT-III \[Human\]) supplementation prior to high-risk, non-emergency, cardiac surgery with cardiopulmonary bypass (CPB). A total of 404 adult subjects undergoing CPB who meet the study eligibility criteria were planned to be randomized to receive either AT-III (Human) or placebo.

The primary objective of this clinical study was to compare the percentage of subjects with any component of a 7 item major morbidity composite (postoperative mortality, stroke, acute kidney injury (\[AKI\]), surgical re-exploration, arterial or venous thromboembolic event, prolonged mechanical ventilation, or infection) between 2 groups of subjects randomly allocated to receive preoperative supplementation of AT-III (Human) (Antithrombin-III (\[Human \]) or Placebo.

The secondary objectives of this clinical study were the following:

* To compare postoperative antithrombin III (AT) levels at the Intensive Care Unit (ICU) admission between the AT-III (Human) treatment group and Placebo control group
* To compare the following perioperative outcomes between the AT-III (Human) treatment group and Placebo control group:

  * Postoperative chest-drain blood loss in the first 12 and 24 hours after surgery
  * Transfusion requirements
  * Need for surgical re-exploration
  * Low cardiac output syndrome
  * Myocardial Infarction (MI)
  * Stroke
  * AKI
  * Arterial or venous thromboembolic events
  * Infections
  * Prolonged mechanical ventilation (\>24 hours)
  * All-cause postoperative mortality
  * ICU stay duration
  * Prolonged ICU stay (\>6 days)
  * Length of hospital stay

Additionally, safety objectives included the evaluation of AT III (Human) for clinical safety including adverse events (AEs), risks for bleeding, clinical laboratory testing, physical exam, and vital signs.

Eligibility Criteria:
Inclusion Criteria:

1. Male or female.
2. At least 18 years of age.
3. Subject needed non-emergency cardiac surgery with CPB.
4. Types of cardiac operations permitted: complex/combined procedures (CABG+valve), double/triple valve repair/replacement, ascending aorta/aortic arch surgeries. Isolated CABG or single valve repair/replacements were allowed only if subject had received preoperative heparin \>2 days.

   - Following the incorporation of Protocol Version 4.0 (Amendment 3 dated 02 Apr 2015), this criterion was revised to include complex/combined procedures (CABG+valve), double/triple valve repair/replacements, ascending aorta/aortic arch surgeries (without baseline AT level restriction or preoperative heparin requirement). OR isolated CABG or single valve repair/replacements were allowed only if either (a) AT level was less than 80% OR (b) preoperative heparin was received (\[UFH for at least 12 hours; LMWH for more than 5 days).
5. Subject had a baseline AT level of less than 80%.

   * Following incorporation of Protocol Version 3.0 (Amendment 2 dated 02 Sep 2014) this was changed to Subject had a Prescreening/Screening and baseline local lab AT level of less than 80%.
   * Following the incorporation of Protocol Version 4.0 (Amendment 3 dated 02 Apr 2015) this criterion was deleted and noted as "Not applicable - intentionally left blank for data management purposes (consistency in eCRF capture of eligibility criteria historically)."
6. Subject had signed informed consent form.
7. Subject was willing to comply with all aspects of the protocol, including blood sampling, for the total duration of the study.

Exclusion Criteria:

1. Subject needed emergency surgery.
2. Subject needed heart transplantation.
3. Subject needed the use of minimally invasive surgery.
4. Subject had previous cardiac operation.
5. Subject had infective endocarditis.
6. Subject had thromboembolic events, stroke, or ST-elevated MI within 7 days of surgery.
7. Subject had cardiogenic shock at the time of surgery.
8. Subject had renal dysfunction: creatinine levels \>2 mg/dL or chronic dialysis.
9. Subject had liver dysfunction: aspartate aminotransferase (AST), alanine aminotransferase (ALT) increase ≥2-fold above the upper-limit of local lab normal ranges.
10. Subject had treatment with Clopidogrel® and Ticagrelor® within 5 days before surgery, Prasugrel® within 7 days before surgery, glycoprotein IIb/IIIa receptor blockers within 24 hours of surgery.
11. Subject had treatment with new oral anticoagulants (Apixaban®, Rivaroxaban®, Dabigatran®) within 48 hours before surgery.
12. Subject had Vitamin K antagonist therapy and an international normalized ratio (INR) \>1.3 on the day of surgery.
13. Subject had platelet count \<120,000/μL.
14. Subject had history or suspicion of a congenital or acquired coagulation disorder.
15. Subject had history of anaphylactic reaction(s) to blood or blood components.
16. Subject had allergies to excipients in the study drug.
17. Subject had refused to receive allogenic transfusion of blood-derived products.
18. Subject had received AT treatment within the last 3 months prior to Screening Visit.
19. Subject was pregnant. Subject had participated in any another investigational study within the last 3 months prior to Screening Visit.