Antithrombin after cardiac surgery: implications on short and mid-term outcome

Area of Science:

• Cardiology
• Hematology
• Surgical Outcomes

Background:

• Antithrombin (AT) levels can decrease during cardiac surgery, but the causes and consequences remain unclear.
• Understanding the impact of postoperative AT levels on patient outcomes is essential for improving cardiac surgical care.

Purpose of the Study:

• To investigate the relationship between postoperative Antithrombin (AT) levels and short-term (in-hospital) and mid-term (18-month) outcomes following cardiac surgery.
• To determine if a low Antithrombin (AT) level upon ICU arrival is a predictor of adverse events and survival.

Main Methods:

• A cohort of 405 patients undergoing cardiac surgery between January and June 2005 had their Antithrombin (AT) levels measured preoperatively and postoperatively.
• Receiver Operating Characteristic (ROC) curve analysis identified a cut-off of 63.7% for ICU-arrival AT to stratify patients into 'Low AT' (<63.7%) and 'High AT' (>=63.7%) groups.
• Outcomes assessed included in-hospital mortality, morbidity (mechanical ventilation, inotropic support, bleeding, transfusion), and 18-month survival.

Main Results:

• ICU-arrival AT levels were significantly lower than preoperative levels (71.2% vs. 90.7%, P < 0.0001).
• The 'Low AT' group (n=117) exhibited characteristics of higher surgical risk, including older age, female sex, worse Euroscore, and longer cardiopulmonary bypass and cross-clamp times.
• While not linked to in-hospital mortality, ICU-arrival AT < 63.7% independently predicted longer mechanical ventilation, increased need for inotropic support, excessive bleeding, and blood product transfusion.
• The 'Low AT' group showed significantly worse 18-month survival (85.4%) compared to the 'High AT' group (92.3%, P = 0.05).

Conclusions:

• Reduced Antithrombin (AT) levels post-cardiac surgery are associated with a higher incidence of peri-operative complications.
• Low Antithrombin (AT) levels are a significant predictor of worse mid-term survival after cardiac surgery.
• Further research is warranted to elucidate the underlying pathophysiology and explore potential therapeutic interventions for managing low AT levels.