Antithrombin as a Predictor of Heparin Resistance in Cardiac Surgery With Cardiopulmonary Bypass

NCT07549568 | Not Yet Recruiting

• 1 other identifier: ANTITHROMBIN-HLM-2026
• Study Type: observational
• Target: 300
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to investigate whether the level of antithrombin (AT) in the blood before cardiac surgery can predict how well patients respond to heparin, a medication used to prevent blood clotting during surgery with a heart-lung machine (cardiopulmonary bypass). Heparin requires antithrombin to work effectively. Some patients have lower levels of antithrombin, which may result in reduced response to heparin, a condition known as heparin resistance. This can lead to difficulties achieving adequate anticoagulation during surgery and may require additional medication or adjustments in treatment. In this study, an additional blood sample will be taken after anesthesia induction but before the administration of heparin. No changes will be made to the patient's treatment or care. Clinical data, including laboratory values, heparin dosing, and surgical outcomes, will be collected from routine medical records. The goal is to identify a clinically useful antithrombin threshold that can help detect patients at risk of heparin resistance. This may improve patient safety, optimize treatment strategies, and reduce unnecessary use of antithrombin therapy in the future.

Conditions

Heparin Resistance; Cardiac Surgery; Cardiopulmonary Bypass

Keywords

Antithrombin; Antithrombin III; Heparin resistance; Activated clotting time; ACT; Cardiopulmonary bypass; Cardiac surgery; Anticoagulation; Heparin response; Predictive biomarker

Outcome Measures

Primary Outcomes (1)

• Heparin resistance

  Heparin resistance defined as failure to achieve an activated clotting time (ACT) ≥480 seconds after administration of an initial heparin dose of 350 IU/kg, according to standard clinical practice.

  Intraoperative (immediately after initial heparin administration)

Secondary Outcomes (3)

• Activated clotting time after initial heparin dose

  Intraoperative (after initial heparin administration)

• Total heparin dose

  Intraoperative

• Antithrombin supplementation

  Intraoperative

Study Arms (1)

Patients undergoing cardiac surgery with cardiopulmonary bypass

Adult patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) at Sahlgrenska University Hospital, Sweden. All patients are managed according to standard clinical practice. A preoperative blood sample is collected to measure antithrombin levels, and clinical data are collected to assess the relationship between antithrombin levels and heparin resistance. No study-specific intervention is performed.

Other: No intervention (observational study)

Interventions

No intervention (observational study) OTHER

This is a prospective observational study. No intervention is assigned as part of the study protocol. All patients receive standard clinical care. A preoperative blood sample is collected for measurement of antithrombin levels, and clinical data are recorded to assess the relationship between antithrombin levels and heparin resistance without influencing treatment.

Patients undergoing cardiac surgery with cardiopulmonary bypass

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adult patients undergoing elective or sub-acute cardiac surgery with cardiopulmonary bypass at Sahlgrenska University Hospital, Sweden. Patients are consecutively included to reflect routine clinical practice and minimize selection bias.

You may qualify if:

• Age ≥18 years
• Planned cardiac surgery with cardiopulmonary bypass
• Ability to provide informed consent

You may not qualify if:

• Emergency cardiac surgery
• Ongoing antithrombin supplementation prior to surgery
• Known severe congenital coagulation disorder affecting interpretation of outcomes
• Severe liver failure
• Missing key data required to define heparin resistance (e.g., missing heparin dose or ACT values)

Sponsors & Collaborators

• Sahlgrenska University Hospital: lead

Study Sites (1)

Sahlgrenska University Hospital

Gothenburg, Västra Götalandsregionen, 41345, Sweden

Location

Related Publications (3)

• Chen Y, Phoon PHY, Hwang NC. Heparin Resistance During Cardiopulmonary Bypass in Adult Cardiac Surgery. J Cardiothorac Vasc Anesth. 2022 Nov;36(11):4150-4160. doi: 10.1053/j.jvca.2022.06.021. Epub 2022 Jun 24.

  PMID: 35927191 BACKGROUND

• Levy JH, Sniecinski RM, Maier CL, Despotis GJ, Ghadimi K, Helms J, Ranucci M, Steiner ME, Tanaka KA, Connors JM. Finding a common definition of heparin resistance in adult cardiac surgery: communication from the ISTH SSC subcommittee on perioperative and critical care thrombosis and hemostasis. J Thromb Haemost. 2024 Apr;22(4):1249-1257. doi: 10.1016/j.jtha.2024.01.001. Epub 2024 Jan 11.

  PMID: 38215912 BACKGROUND

• Rivera Jimenez KE, Mamani Ticona YM, Gutierrez-Chavez G, Astudillo CO, Calle E, Heredia GAT, Lopez Delgado DS, Rivera-Lozada O, Barboza JJ. Heparin Resistance in Cardiac Surgery with Cardiopulmonary Bypass: Mechanisms, Clinical Implications, and Evidence-Based Management. Medicina (Kaunas). 2025 Nov 23;61(12):2088. doi: 10.3390/medicina61122088.

  PMID: 41470090 BACKGROUND

MeSH Terms

Interventions

Observation

Intervention Hierarchy (Ancestors)

Methods; Investigative Techniques

Study Officials

• Anna Corderfeldt Keiller, PhD

  Sahlgrenska University Hospital and University of Gothenburg, Department of Clinical Sciences, Gothenburg, Sweden

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Anna Corderfeldt Keiller, PhD

CONTACT

+46313427737; anna.corderfeldt@gu.se

Daniel Bengtsson, MSc

CONTACT

+313427730; daniel.bengtsson@vgregion.se

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Senior Perfusionist, PhD

Study Record Dates

• First Submitted: April 16, 2026
• First Posted: April 24, 2026
• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): October 1, 2027
• Study Completion (Estimated): May 1, 2028
• Last Updated: May 4, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ANALYTIC CODE
• Time Frame: Data will be available beginning 6 months following publication of the primary results and will remain available for at least 5 years thereafter.
• Access Criteria: Access to de-identified individual participant data and supporting documentation (study protocol, statistical analysis plan, and analytic code) will be granted to qualified researchers upon reasonable request. Requests must include a methodologically sound research proposal and, where applicable, approval from a relevant ethics committee. Data will be made available following approval of a data access agreement, in compliance with applicable legal and ethical requirements, including the General Data Protection Regulation (GDPR, EU 2016/679) and Swedish data protection legislation. Data and analytic code will be accessed through DORIS, a secure research data repository at the University of Gothenburg, and will not be publicly downloadable.

Locations

SE (1)