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

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.