Fibrinogen reduction and coagulation in cardiac surgery: an investigational study

Area of Science:

• Cardiovascular Surgery
• Hematology
• Coagulation Science

Background:

• Fibrinogen is crucial for blood clot formation, acting as the precursor to fibrin.
• Cardiac surgery, particularly with cardiopulmonary bypass, can lead to decreased fibrinogen levels via hemodilution, consumption, and degradation.
• Fibrinogen degradation products (FgDPs) may interfere with normal fibrin formation and clot integrity.

Purpose of the Study:

• To quantify the contributions of hemodilution, consumption, and degradation to fibrinogen loss during cardiac surgery.
• To assess the in vitro effects of early fibrinogen degradation products on blood clot formation.

Main Methods:

• Comparison of fibrinogen, fibrin, degradation products, hematocrit, and albumin levels before and after coronary artery bypass graft (CABG) surgery in 10 patients.
• Ex vivo fibrinogen supplementation experiments.
• In vitro assessment of purified FgDPs' effects on clotting time and clot firmness using rotational thromboelastometry (ROTEM).

Main Results:

• Fibrinogen plasma concentration decreased by 30% post-CABG surgery.
• The observed drop in fibrinogen was primarily attributed to hemodilution, indicated by decreased hematocrit and albumin levels, with no significant increase in D-dimer or FgDPs.
• Fibrinogen supplementation normalized the coagulation profile.
• Purified early FgDPs significantly impaired in vitro whole blood clotting, affecting clotting time and clot firmness.

Conclusions:

• Hemodilution is the principal mechanism for fibrinogen reduction following CABG surgery when tranexamic acid is used.
• While early FgDPs significantly impact in vitro clot formation and may contribute to coagulopathy, they are not the primary driver of fibrinogen decrease in this surgical context.